In 2005, the Energy Facilities Siting Board (siting board), acting pursuant to G. L. c. 164, § 69J (§ 69J), approved the petition of Cape Wind Associates, LLC (Cape Wind), to build and operate two 115 kilovolt underground and undersea electric transmission cables or lines (transmission project, or transmission Unes) that would connect Cape Wind’s proposed offshore wind-powered energy generating facility (wind farm) to the regional electric power grid. This court affirmed the siting board’s decision. Alliance to Protect Nantucket Sound, Inc. v. Energy Facilities *666Siting Bd., 448 Mass. 45, 56 (2006) (Alliance I). Actual construction of the transmission lines, however, requires additional permits, licenses, and approvals from a number of different State and local authorities.
In 2007, the Cape Cod Commission (commission) denied Cape Wind’s proposed development of regional impact (DRI); approval of the DRI by the commission was one of the required “approvals” for the transmission project. Soon thereafter, Cape Wind applied to the siting board pursuant to G. L. c. 164, § 69K (§ 69K), for a “certificate of environmental impact and public interest” (certificate, or § 69K certificate) that would constitute a “composite” of the “individual permits, approvals or authorizations which would otherwise be necessary for the construction and operation” of the transmission project. Id. After conducting an adjudicatory proceeding, the siting board granted the requested certificate in May, 2009. Three of the interveners in the certificate proceeding appeal from the siting board’s decision pursuant to G. L. c. 164, § 69P, and G. L. c. 25, § 5: the Alliance to Protect Nantucket Sound (Alliance), the commission, and the town of Barnstable (Barnstable) (collectively, petitioners). They seek reversal of the decision, and also request that we declare invalid a regulation of the Department of Environmental Protection (DEP). We affirm the decision of the siting board and conclude that the challenged regulation is valid.
Background.5 Cape Wind plans to construct a wind farm consisting of 130 wind turbine generators, each 440 feet tall, on Horseshoe Shoal in Nantucket Sound, a location that is more than three miles from any Commonwealth coast and entirely in Federal waters. As a result, the wind farm itself requires only Federal permits. However, the transmission lines at issue in this case, which Cape Wind proposes to build to connect the wind farm to the regional power grid, will pass under Massachusetts territorial waters in Lewis Bay and Nantucket Sound for approximately six miles and therefore require State and local permits, licenses, and approvals for their construction and operation. The *667transmission lines — two cables, each comprised of three copper conductors and one fiber optic cable bundled together — will carry electricity across an approximately 18.4 mile route, running under the seabed through Nantucket Sound and Lewis Bay for 12.5 miles, coming ashore in the town of Yarmouth (Yarmouth), and continuing underground for 5.9 miles through Yarmouth and Barnstable to an existing switching station in Barnstable.
Cape Wind’s efforts to secure the necessary Federal and, of greater significance here, State and local regulatory approvals for its wind farm and transmission project have a lengthy history. In November, 2001, Cape Wind began to seek the permits required for the transmission project by fifing an expanded environmental notification form (ENF) with the Executive Office of Energy and Environmental Affairs (EOEEA). The filing set in motion a joint review by the EOEEA under the Massachusetts Environmental Protection Act (MEPA),6 and by the commission under § 12 (i) of St. 1989, c. 716, “An Act establishing the Cape Cod commission” (Cape Cod Act). Cape Wind stated in the ENF that it sought a DRI approval from the commission. After holding a public hearing, the Secretary of the EOEEA determined that the transmission project would require Cape Wind to file an environmental impact report (EIR) in order to comply with MEPA, and outlined *668the scope of the joint DRI-EER review. Pursuant to a memorandum of understanding with the EOEEA, the commission held public hearings and submitted comment letters to provide input for the MEPA review.
*667“Because MEPA (like the Cape Cod Commission Act) is the product of state law, not federal law, MEPA review (and by extension Cape Cod Commission review) applies only to those portions of the project that are located within Massachusetts, including its territorial waters (generally within three nautical miles of the low water mark of the shore). The proposed [wind farm] is located outside of Massachusetts and, therefore, is not subject to state regulatory requirements. There is one notable exception . . . federal law (pursuant to the Coastal Zone Management Act) specifically delegates review authority over projects in federal waters to the Coastal Zone Management Office of the adjacent coastal state . . . .”
*668In 2002, Cape Wind sought permission from the siting board pursuant to § 69J, to construct the transmission lines.7’8 “The approval of the [siting] board is required prior to the commencement of construction of any ‘facility’[9] ... in the Commonwealth, and no State agency may issue a construction permit for any such facility unless the petition to construct the facility has already received approval from the [siting] board.” Alliance I, 448 Mass, at 46-47, citing § 69J. Following a three-year review, the siting board approved construction of the transmission line facility under § 69J in 2005,10 a decision this court affirmed in 2006. See id. at 56.
*669In March, 2007, the Secretary of the EOEEA issued a final environmental impact report, finding the transmission project in compliance with MEPA. Cape Wind then renewed its efforts to obtain DRI approval from the commission. In deciding whether to grant such approval under the Cape Cod Act, St. 1989, c. 716, the commission assesses whether a project complies with minimum performance standards (MPS) set forth in its regional policy plan (RPP), a county ordinance enacted under the Barn-stable County Home Rule Charter. St. 1988, c. 163.
In its review of Cape Wind’s DRI application, the commission first deemed it incomplete for failure to include certain engineering plans and proof of control of the property along the transmission line route. Nevertheless, the commission held three days of public hearings in May, 2007, and after receiving additional information from Cape Wind, found the application complete as of August 3, 2007. The commission closed public hearings on August 8, 2007, triggering, under § 13 (a) of the Cape Cod Act, a sixty-day period for the commission to make a decision, in the absence of which Cape Wind’s DRI application would receive constructive approval. The commission held additional public hearings in September, 2007, and sought still more information. At the commission’s request, on September 11, 2007, Cape Wind agreed to extend the decision deadline to October 21, 2007, and provided responses to the specific information requests. On October 18, 2007, the commission denied the DRI application “without prejudice” on grounds that Cape Wind had not submitted the full body of information that it had sought and that Cape Wind would not agree to another extension of the decision deadline.11-12
Cape Wind did not appeal from the DRI decision, but in November, 2007, filed an initial petition with the siting board *670to obtain a § 69K certificate.13 See 980 Code Mass. Regs. § 6.00 (1993). As previously indicated, such a certificate, if issued, serves as “a composite of all individual permits, approvals or authorizations which would otherwise be necessary for the construction and operation of the facility.” G. L. c. 164, § 69K. Cape Wind requested that the certificate include the equivalent of the necessary DRI approval by the commission, and eight additional State and local permits. Among the eight was a tidelands license under G. L. c. 91 (c. 91); tidelands licenses are generally within the regulatory jurisdiction of DER See c. 91, § 14.14
In December, 2007, Cape Wind filed a formal certificate application, which the siting board consolidated with Cape Wind’s initial petition. See G. L. c. 164, § 69L; 980 Code Mass. Regs. §§ 6.02, 6.03. The siting board granted intervener status to the five government entities with permits at issue — Barnstable, Yarmouth, DEP, the Executive Office of Transportation and Public Works, and the commission; and to three nonprofit *671organizations — Conservation Law Foundation, Clean Power Now, Inc., and the Alliance. See G. L. c. 164, § 69N.15 From August through October, 2008, the parties conducted written discovery. Cape Wind, the commission, and DEP each submitted prefiled testimony of witnesses. Also before the siting board were 330 exhibits, consisting mainly of responses to information requests.16 The siting board’s presiding officer held two days of hearings, during which witnesses whose direct testimony had been prefiled were subject to cross-examination. The siting board issued a tentative decision on May 11, 2009, and then a final decision granting the certificate on May 21, 2009.
Each of the petitioners filed an appeal from the siting board’s decision in the county court pursuant to G. L. c. 164, § 69P, and G. L. c. 25, § 5. A single justice consolidated the petitioners’ appeals, consolidated with them Barnstable’s and the commission’s appeal in an action Barnstable and the commission had brought against the siting board in the Superior Court,17 and reserved and reported these appeals to this court, along with stipulations concerning claims for declaratory relief brought by the Alliance and Barnstable.18 We refer to additional facts from the siting board’s administrative record where pertinent to the discussion that follows.
*672Discussion. Each of the petitioners challenges the siting board’s decision on several grounds, and the Alliance and Barn-stable separately challenge the validity of a DEP regulation relevant to that decision, 310 Code Mass. Regs. § 9.12(2)(b)(10) (2008). We discuss first the challenges that may be described loosely as claims concerning aspects of the siting board’s jurisdictional authority in this case; we then review the challenges that go to the validity of the siting board’s decision. Finally, we consider the challenge to the DEP regulation.19
A. Jurisdictional authority claims. 1. Authority to override a DRI decision by the commission. The petitioners assert that the siting board had no jurisdiction under § 69K to grant the equivalent of an approval of Cape Wind’s DRI, and thereby to override the commission’s denial. We consider each of their arguments, and conclude that none has merit.
a. Cape Cod Act. Section 17 (b) of the Cape Cod Act states that “[a]ny party aggrieved by a commission decision on a [DRI] may appeal the commission’s decision to the Barnstable county superior court or the land court”; § 17 (d), in turn, provides that “[t]he foregoing remedy shall be exclusive.” The petitioners take the position that the Cape Cod Act, enacted in 1989, controls as more specific and more recent legislation than the siting board’s enabling statute, G. L. c. 164, §§ 69G-69Q (siting board statute), originally enacted in 1973. Accordingly, in their view, § 17 (d) of the Cape Cod Act provides Cape Wind’s exclusive avenue to challenge the commission’s DRI denial.
*673We presume that the Legislature acts with full knowledge of existing laws. Suliveres v. Commonwealth, 449 Mass. 112, 116 (2007). Commonwealth v. Callahan, 440 Mass. 436, 440-441 (2003). Thus, “[w]hen construing two or more statutes together, ‘[w]e are loath to find that a prior statute has been superseded in whole or in part in the absence of express words to that effect or of clear implication.’ Registrar of Motor Vehicles v. Board of Appeal on Motor Vehicle Liab. Policies & Bonds, [382 Mass. 580, 585 (1981)]. ‘The longstanding test for the principle of implied repeal is whether the prior statute is so repugnant to, and inconsistent with, the later enactment that both cannot stand. Only then is the former statute repealed.’ Commonwealth v. Graham, 388 Mass. 115, 125 (1983).” Dedham Water Co. v. Dedham, 395 Mass. 510, 518 (1985).
Applying these principles here, we find no disabling inconsistency between the siting board statute and the Cape Cod Act. Rather, as the facts of these cases illustrate, the two statutes can be read together, giving meaning and purpose to both.20 See Commonwealth v. Harris, 443 Mass. 714, 725 (2005) (“Rather than mechanically applying the concept that the more ‘recent’ or more ‘specific’ statute . . . trumps the other, we should endeavor to harmonize the two statutes so that the policies underlying both may be honored”). Under § 69L (A) (4) of the siting board statute, an applicant for a certificate must first try to obtain the necessary regulatory approvals from the relevant permitting agencies. Cape Wind followed this course with respect to its DRI, seeking the commission’s approval in the first instance. Accordingly, the commission had the opportunity to review the transmission project under the relevant provisions of the Cape Cod Act and the commission’s implementing regulations. When the commission exercised its authority to deny the DRI, the petitioners are correct that Cape Wind could have appealed under § 17 of the Cape Cod Act. However, the denial also triggered Cape Wind’s independent right to seek a certificate from the siting board under § 69K,21 a course that Cape Wind pursued. *674And § 69K directs that when the siting board issues a certificate, ‘ ‘ [n] otwithstanding the provisions of any other law to the contrary . . .no state agency or local government shall impose or enforce any law, ordinance, by-law, rule or regulation nor take any action . . . which would delay or prevent the construction, operation or maintenance of such facility” (emphasis added).
As this review indicates, the two statutes can operate harmoniously together. The fact that § 69K authorizes the siting board to issue a certificate for a particular project that supersedes a commission decision under the Cape Cod Act does not thereby make the statutes inconsistent.22 The commission’s construction of the two statutes would have § 69K, and the siting board statute generally, apply everywhere in the Commonwealth except Barnstable County, a reading inconsistent with the siting board’s responsibility “to provide a reliable energy supply for the commonwealth'’'’ (emphasis added). G. L. c. 164, § 69H. See City Council of Agawam v. Energy Facilities Siting Bd., 437 Mass. 821, 828 (2002) (City Council of Agawam) (“the intent and purpose of the [siting board] statute ... is in part to ensure that local boards do not use their power over licenses and permits to thwart the needs of the broader community for a reliable, affordable, and environmentally sound energy supply”).23
b. The commission as local agency or body. The first paragraph *675of § 69K authorizes an electric company to seek a certificate from the siting board if its proposed “facility cannot be constructed due to any disapprovals, conditions or denials by a state or local agency or body (emphasis added); the phrase “local agency or body” is not defined. The section also uses the term “local government,” which is defined in G. L. c. 164, § 69G, to mean, “any political subdivision of the commonwealth, including any county, city, town, district agency or regional agency.” The Cape Cod Act, in turn, states that the commission “shall be the regional planning agency for Cape Cod” and that it “shall be an agency within the structure of [the] Barnstable county government.” St. 1989, c. 716, § 3 (a). The petitioners contend that as defined or described in the Cape Cod Act, the commission qualifies as a “local government,” but not as a “local agency or body” for purposes of § 69K. Accordingly, they claim, the commission’s denial of a DRI cannot properly serve as the basis for a petition to the siting board for a certificate. The argument fails. We agree with the siting board that when one reads § 69K as a whole, it is clear that the Legislature has used the term “local government,” “local agency,” and “local agency or body” interchangeably.24 And as we discuss later in connection with *676another provision in § 69K, the siting board’s interpretation is entitled to respect and deference. See City Council of Agawam, 437 Mass, at 828. Moreover, the commission is defined in § 3 (a) of the Cape Cod Act as a “regional” agency within the structure of “county government.” As such, the commission is clearly a local (as opposed to State) agency, and therefore it qualifies as a “local agency or body” within the meaning of § 69K in any event.
2. Authority to include the equivalent of a c. 91 tidelands license in a § 69K certificate. The Alliance, joined by Barn-stable, claims that § 69K does not authorize the siting board to include in a certificate granted under that section any type of license relating to the Commonwealth’s tidelands.25 The argument is that these tidelands are both owned and held in trust by the Commonwealth to protect the public’s rights in them, and that no one — including a State agency such as the siting board — may claim authority to act in connection with the tidelands unless granted express legislative authority to do so. The Alliance contends that § 69K contains no language of delegation or even mention of the tidelands or the public trust with which they are imbued, and therefore, the siting board cannot grant a certificate that incorporates, in effect, a c. 91 tidelands license.
The public trust doctrine expresses the government’s longstanding and firmly established obligation to protect the public’s interest in the tidelands and, in particular, to protect the public’s right to use the tidelands “for, traditionally, fishing, fowling, and navigation.” Moot v. Department of Envtl. Protection, 448 Mass. 340, 342 (2007) (Moot I). See Trio Algarvio, Inc. v. Commissioner of the Dep’t of Envtl. Protection, 440 Mass. 94, *67797 (2003); Fafard v. Conservation Comm’n of Barnstable, 432 Mass. 194, 198 (2000) (Fafard); Boston Waterfront Dev. Corp. v. Commonwealth, 378 Mass. 629, 632 (1979). There is no question that the Commonwealth tidelands through which Cape Wind’s transmission lines will pass are held in the public trust to which the Alliance refers. We also agree with the Alliance that under the public trust doctrine, “only the Commonwealth, or an entity to which the Legislature properly has delegated authority, may administer public trust rights.” Fafard, supra at 199. See id. at 196. See also Commonwealth v. Charlestown, 1 Pick. 180, 184-185 (1822). The question, then, is whether the Legislature in § 69K “properly has delegated authority,” Fafard, supra at 199, to the siting board to exercise public trust rights. The answer requires examination of c. 91, the waterways statute administered by DEP, § 69K, and the statutory scheme of which § 69K is a part.
The Legislature has delegated to DEP the authority to license “structures” in the Commonwealth’s tidelands, provided that they “serve a proper public purpose and that said purpose shall provide a greater public benefit than public detriment to the rights of the public in said lands.” G. L. c. 91, § 14. See id. at § 18. In doing so, DEP is to “protect the interests of the Commonwealth” in the tidelands. Id. at § 2. Section 69K, in turn, grants authority to the siting board to issue a certificate in accordance with §§ 69K-690, which
“shall be in the form of a composite of all individual permits, approvals or authorizations which would otherwise be necessary for the construction and operation of the facility[26] and that portion of the certificate which relates to subject matters within the jurisdiction of a state or local agency shall be enforced by said agency under the applicable laws of the commonwealth as if it had been directly granted by the said agency” (emphasis added).
*678We read the quoted provision in § 69K as an express legislative directive to the siting board to stand in the shoes of any and all State and local agencies with permitting authority over a proposed “facility” — that is, a directive to assume all the powers and obligations of such an agency with respect to the decision whether to grant the authorization that is within the agency’s jurisdiction, with regulatory enforcement thereafter returned to that agency. DEP, as a State agency, is by definition included within the broad coverage of § 69K. There is no mention of public trust rights or obligations in § 69K, but there does not need to be. The Legislature has designated DEP as the agency charged with responsibility for protecting public trust rights in tidelands through the c. 91 licensing program, and where a tidelands license is necessary for a proposed facility, the Legislature has, in § 69K, expressly vested authority in the siting board to act in DEP’s stead with respect to the initial permitting decision. Accordingly, an evaluation of § 69K’s relationship to the public trust doctrine must take into account the fact that in a case such as this, § 69K operates as an overlay of c. 91.
Other sections of the siting board statute support our reading of § 69K, most significantly, G. L. c. 164, § 690 (§ 690). That section specifies the issues on which the siting board must make findings in its decision whether or not to grant a § 69K certificate, and provides that the siting board must take into account whether the facility seeking the certificate will conform to the various laws, ordinances, and regulations that would otherwise govern it in the absence of a § 69K certificate. G. L. c. 164, § 690 (3). See note 36, infra, where § 690 is quoted in full. One set of such laws is c. 91, §§ 2, 14 and 18, with their requirement that DEP protect the public’s interest in tidelands in issuing any license or permit pursuant to c. 91. Because § 69K delegates to the siting board both the power and the obligation to stand in the shoes of DEP, if DEP had not made the findings that the siting board adopted here,27 the siting board would have had to undertake the same reviewing process that *679DEP did in evaluating Cape Wind’s c. 91 tidelands license application.28
In sum, we find in § 69K a sufficiently articulated legislative delegation of authority to the siting board to act in the place of DEP, and to administer the public trust rights within DEP’s jurisdiction in the limited context of deciding whether to approve the equivalent of a c. 91 tidelands license.29 Contrast *680Fafard, 432 Mass, at 198-199, 207 (where there was no grant of authority by Legislature, local conservation commission could not exercise public trust rights, and bylaw purporting to do so was invalid). Contrast also Moot I, 448 Mass, at 347-353.30 Accordingly, the siting board in this case did not exceed its *681authority by including the equivalent of a c. 91 tidelands license in the certificate it granted Cape Wind.
In reaching this conclusion, we also reject the alternative argument advanced by the Alliance that focuses on the following language in the final clause of § 69K’s first paragraph:
“The [siting] board shall consider [a] petition providing: . . . the facility cannot be constructed due to any disapprovals, conditions or denials by a state or local agency or body, except with respect to any lands or interests therein, excluding public ways, owned or managed by any state agency or local government” (emphasis added).
According to the Alliance, the quoted “except” clause means that the siting board has no power whatsoever to take action with respect to a license or permit that an agency has disapproved, conditioned or denied if that license or permit pertains to “public” lands — that is, lands owned or managed by any State or local agency — including tidelands managed by DEP under c. 91. The siting board considered but disagreed with the Alliance’s argument, concluding:
“Read in context, the [‘except’ clause] in [the first paragraph of § ] 69K means that a petitioner may not rely upon a state agency or local government refusal with respect to public lands as a basis to file an initial petition. However, this language does not govern the scope of the Certificate, which is addressed in the [fifth] paragraph of [§ ] 69K, and which states that a Certificate takes the place of ‘all’ state or local permits” (emphasis in original).
We accord substantial discretion to an agency to interpret the statute it is charged with enforcing, especially where, as here, see § 69H (1), the Legislature has authorized the agency to promulgate regulations. City Council of Agawam, 437 Mass. at 828. See Middleborough v. Housing Appeals Comm., 449 Mass. *682514, 523 (2007) (Middleborough). The siting board’s interpretation of the “except” clause treats it as limiting only the types of permit denials that can serve as a basis for a company to petition for a § 69K certificate, but not as a limitation on the siting board’s authority to review and potentially override that permit denial, if the company has an independent basis on which to file a certificate petition. As the siting board stated, the structure of § 69K supports this interpretation. The first paragraph of the section in which the “except” clause appears is devoted to listing the specific alternative bases that would justify the filing of a certificate petition, but does not discuss the scope or contents of the certificate itself. The fifth paragraph, however, does focus on contents, and describes the certificate as a “composite of all individual permits” otherwise required. While the meaning of the “except” clause is not entirely clear, the siting board’s construction is reasonable, and we defer to it. See Alliance I, 448 Mass, at 50-51 n.6 (“the substantial deference owed to an agency’s interpretation of a statute it is charged to enforce includes approving an interpretation of statutory language that may be read in two ways”). See also Middleborough, 449 Mass, at 523, and cases cited (“Where the statutory language is not without ambiguity . . . , our deference to the agency’s interpretation of the governing statute is highest”). Accordingly, we conclude that the except clause did not prohibit the siting board from considering and acting on Cape Wind’s request for the equivalent of a c. 91 tideland license.
3. Jurisdiction to consider “in-State impacts” of the wind farm. In its decision, the siting board adopted the presiding officer’s determination that it lacked jurisdiction to consider the “in-State impacts” of the wind farm itself due to the location of the wind farm in Federal waters, and therefore that the scope of the certificate proceeding would be limited to the transmission lines only and evidence concerning the wind farms’s impacts would be excluded. See note 14, supra. The petitioners assert that no such jurisdictional limitation exists, and the siting board was obliged to assess the in-State impacts of the entire wind farm project in making its § 69K certificate decision.31
There is no dispute that the wind farm, located entirely in *683Federal waters, will lie outside the jurisdiction of the siting board as well as the State and local permitting agencies with permits at issue in the siting board’s § 69K proceeding. See Alliance I, 448 Mass, at 48 (“The area in which the wind farm itself is proposed to be built is located in Federal waters and, thus, falls beyond the scope of the [siting] board’s jurisdiction”). The petitioners assert, however, that whether as a matter of making the findings required by § 690 or of complying with public trust doctrine obligations, the siting board had the power and the duty to consider the potential effects of the wind farm on the Commonwealth. The thrust of their claim appears to be that as a general tenet of environmental and perhaps all regulation of private development projects, regulatory agencies consider — and must consider — all direct and indirect impacts of the entire project; and because Cape Wind’s transmission lines will connect directly to and service the wind farm, evaluation of the impacts of the wind farm itself was a mandatory part of the siting board’s review of the transmission project. The claim fails for two reasons.
First, the siting board statute generally, and §§ 69J, 69K, and 690 in particular, state with unmistakable clarity that the siting board’s regulatory point of focus at all times is to be on the proposed “facility.” The petitioners do not, and could not, dispute that Cape Wind’s two new 115 kilovolt electric transmission lines constitute the only “facility” subject to the siting board’s review in this case. Accordingly, insofar as § 690 (2) directs the siting board to make findings relating to “considerations of environmental protection, public health and public safety,” those findings are solely to concern “the compatibility of the facility” with such considerations (emphasis added).32 Cf. Villages Dev. Co. v. Secretary of the Executive Office of Envtl. *684Affairs, 410 Mass. 100, 112-115 & n.13 (1991) (where Secretary of [then] EOEA had jurisdiction under MEPA to review private development project based on one necessary State “permit” [grant of easement over bicycle path to construct bridge], MEPA review statutorily restricted to direct and indirect environmental impacts related to easement itself, not impacts of entire development project, even if bridge necessary for entire project to go forward).
The second reason the petitioners’ bid for review of the wind farm’s impacts fails is the one the siting board cites: the wind farm itself will be within Federal jurisdiction, and Federal jurisdiction in this area is paramount. See United States v. Maine, 420 U.S. 515, 522, 524 (1975) (“control and disposition [of all lands underlying sea] in the first instance are the business of the Federal Government rather than the States”; “paramount rights to the offshore seabed inhere in the Federal Government as an incident of national sovereignty”); Ten Taxpayer Citizens Group v. Cape Wind Assocs., LLC, 373 F.3d 183, 196-197 (1st Cir. 2004), cert, denied, 543 U.S. 1121 (2005) (Ten Taxpayer Citizens) (by enacting Outer Continental Shelf Lands Act of 1953 [OCSLA], 43 U.S.C. §§ 1331 et seq., “Congress retained for the federal government the exclusive power to authorize or prohibit specific uses of the seabed beyond three miles from shore”); Alliance to Protect Nantucket Sound, Inc. v. Department of the Army, 398 F.3d 105, 107-108 (1st Cir. 2005).33 Contrary to the Alliance’s claim, the express assertion of exclusive Federal power and control over the outer continental shelf (defined in OCSLA as all submerged lands lying in navigable *685waters beyond three miles from shore, see 43 U.S.C. § 1331[a]), serves to preempt any attempt by the Commonwealth or its agencies to regulate structures or facilities placed in that area. See Ten Taxpayer Citizens, supra at 197 (“If adopted and enforced on the outer Continental Shelf, statutes like [c.] 91 . . . which require[s] the approval of state agencies prior to construction, would effectively grant state governments a veto power over the disposition of the national seabed,” a result “fundamentally inconsistent with the OSCLA”).
If the siting board were to assert authority to consider the impacts of the wind farm itself, as the petitioners argue that it should, presumably that authority would encompass the power to deny or condition Cape Wind’s requested certificate on account of such impacts. But a denial of the certificate on that ground, or even conditioning, would be tantamount to a denial of the wind farm project itself, because, as the siting board found in its § 69J decision approving construction of the transmission project in 2005, the transmission lines are necessary for the wind farm’s operation. See Alliance I, 448 Mass, at 49-50, 55-56. The siting board does not have authority to do indirectly what it cannot do directly. See Ten Taxpayer Citizens, supra. Cf. New England Legal Found, v. Massachusetts Port Auth., 883 F.2d 157, 174 (1st Cir. 1989) (holding defendant authority’s landing fee regulations invalid under Federal law; fee regulations “appear to be an attempt to modify conduct [e.g., control air traffic] rather than to recover operational cost, and are thus an incursion into an area of regulation preempted by [Federal law], [The authority] cannot do indirectly what it is forbidden to do directly”). Contrast Leisure Time Cruise Corp. v. Barnstable, 62 F. Supp. 2d 202, 208-209 (D. Mass. 1999) (where local and regional authorities sought to regulate aspects of actual docking of plaintiff’s boat in Hyannis Harbor, this regulation was “ancillary to Leisure Time’s operation of its gambling cruise” in Federal waters, and not preempted under applicable Federal law). Contrast also North Landers Corp. v. Planning Bd. of Falmouth, 382 Mass. 432, 436-438 (1981) (language of subdivision control statute, G. L. c. 41, § 81M, was clear in authorizing planning board to evaluate adequacy of public way outside proposed subdivision in ruling on subdivision plan); Dupont v. Dracut, 41 Mass. App. Ct. 293, 295 (1996) (under established principles of zoning law, defendant town of Dracut *686could prohibit plaintiff from using portion of single lot located partly in Dracut and partly in Lowell for use not permitted in Dracut zoning district but permitted in Lowell: “Whether in the same or two different municipalities, if a lot is located in two different zoning districts, a town may prohibit the portion in one district from being used for an accessory use to serve a principal use not allowed in that district”).34
We emphasize that the siting board properly could, and did, consider the in-State impacts of the entire length of Cape Wind’s transmission lines even though the lines will lie in part in Federal waters because those impacts relate directly to the “facility” over which the siting board has jurisdiction. See Leisure Time Cruise Corp. v. Barnstable, supra. In doing so, the siting board met its public trust obligations arising from the fact that the facility under review is located in Commonwealth tidelands. Here, the siting board, through the presiding officer, allowed the testimony of the petitioners’ witnesses so far as it pertained to the transmission project; the testimony deemed inadmissible related solely to the claimed impacts of the wind farm’s turbines. See note 16, supra. The siting board’s presiding officer did not abuse her discretion or commit other error of law by ruling that evidence related to general in-State impacts of the wind turbines, unconnected to the transmission project, was inadmissible.
The wind farm, including its in-State impacts, has undergone extensive scrutiny by Federal and State agencies. In addition to the National Environmental Policy Act review by the Minerals Management Service, see note 6, supra, the Coastal Zone Management Office (CZM) has certified to Federal permitting authorities that Cape Wind’s entire project, including the wind farm, will be consistent with CZM policies.35 Moreover, the siting board has conditioned the certificate it granted Cape Wind *687for the transmission project on Cape Wind’s receipt of all necessary Federal and State permits for the wind farm. In reviewing the siting board’s decision under § 69J to authorize Cape Wind’s construction of the transmission lines, this court approved of the siting board’s determination that it was required to defer to Federal review. See Alliance I, 448 Mass, at 53-54. We do so again here.
4. Cape Wind’s organizational status. Section 69K provides that “[a]ny electric . . . company which proposes to construct or operate facilities in the commonwealth may petition the siting board for a certificate.” The term “electric company” is defined in G. L. c. 164, § 1, as “a corporation organized under the laws of the commonwealth for the purpose of making . . . selling, transmitting, distributing, transmitting and selling, or distributing and selling, electricity within the commonwealth.” The commission argues that because a limited liability company is not a corporation, see G. L. c. 156C, § 2 (5); CFM Buckley7 North, LLC v. Assessors of Greenfield, 453 Mass. 404, 407 (2009), Cape Wind does not qualify as an electric company as defined by § 1, and, thus, the siting board had no jurisdiction to entertain its certificate petition under § 69K. While questions of subject matter jurisdiction may be raised at any time, Commonwealth v. DeJesus, 440 Mass. 147, 151 (2003); Litton Business Sys., Inc. v. Commissioner of Revenue, 383 Mass. 619, 622 (1981), the commission has waived the issue by failing to raise it before the siting board. “The question at the heart of subject matter jurisdiction is, ‘Has the Legislature empowered the [agency] to hear cases of a certain genre?’ ” Doe, Sex Offender Registry Bd. No. 3974 v. Sex Offender Registry Bd., ante 53, 56-57 (2010) (Doe No. 3974), quoting Wachovia Bank, Nat’l Ass’n v. Schmidt, 546 U.S. 303, 316 (2006). See Middleborough, 449 Mass, at 520, quoting Black’s Law Dictionary 870 (8th ed. 2004) (“Subject matter jurisdiction is ‘jurisdiction over the nature of the case and the type of relief sought’ ”). The Legislature has designated the siting board as the administrative authority empowered to hear and grant petitions for certificates or composite *688permits sought by entities who claim that actions by other permitting agencies are preventing or delaying their ability to move forward with energy projects. Whether a petitioning entity has a permissible organizational form is not a question of siting board subject matter jurisdiction but one that concerns a substantive element of the entity’s prima facie case for relief. See Middle-borough, supra at 520-521. See also Doe No. 3974, supra at 57. Cf. Arbaugh v. Y & H Corp., 546 U.S. 500, 516 (2006) (employer discrimination case under Title VII of Civil Rights Act of 1964; after judgment entered in plaintiff’s favor, employer moved to dismiss for want of Federal subject matter jurisdiction, asserting for first time insufficient number of employees to be subject to Act; court rejected argument: “the threshold number of employees for application of Title VII is an element of a plaintiff’s claim for relief, not a jurisdictional issue”). Because the commission failed to raise the claim before the siting board — or indeed, at any point before its reply brief on appeal to this court, see Assessors of Boston v. Ogden Suffolk Downs, Inc., 398 Mass. 604, 608 n.3 (1986) — it is waived.
B. Certificate decision. We turn from issues regarding the scope of the siting board’s § 69K certificate authority to the substance of its certificate decision. In that decision, the siting board found that Cape Wind satisfied the requirements set forth in § 69036 by showing that the transmission project was (1) needed; (2) compatible with considerations of environmental *689protection, public health, and safety; (3) in conformance with State and local laws, except for limited aspects of the Cape Cod Act and the RPP, exemption from which was reasonable and consistent with the siting board’s statutory mandate to provide a reliable energy supply with a minimum impact on the environment at the lowest possible cost; and (4) required to serve the public interest and convenience. The siting board also found that Cape Wind had complied with G. L. c. 164, § 69L (A) (4),37 by making a good faith effort to obtain the authorizations included in the certificate: the DRI approval, four local permits Cape Wind could not obtain without DRI approval,38 and four State authorizations, three of which Cape Wind had already received.39
“[A]n applicant for a certificate shall file with the [siting] board a petition . . . containing . . . : (4) A statement setting forth the need of the applicant for the certificate, which . . . shall include ... a representation as to the good faith effort made by the applicant to obtain from state agencies and local governments the licenses, permits and other regulatory approvals required by law for construction or operation of the facility . . . .”
*6901. Standard of review. The petitioners attack the substance of the certificate decision on multiple grounds. Our standard of review is defined in G. L. c. 164, § 69P, and pursuant to that section, we review each claim to determine whether the siting board’s decision
“is in conformity with the constitution of the commonwealth and the constitution of the United States, was made in accordance with the procedures established under [G. L. c. 164, §§ 69H-690,] and with the rules and regulations of the [siting] board with respect to such provisions, was supported by substantial evidence of record in the [siting] board’s proceedings; and was [not] arbitrary, capricious or an abuse of the [siting] board’s discretion under the provisions of [§§ 69H-69G].”
“Consistent with well-established principles of administrative law, we give great deference to the [siting] board’s expertise and experience.” Alliance I, 448 Mass, at 51. Our “review does not turn on whether, faced with the same set of facts, we would have drawn the same conclusion as [the siting board], but only ‘whether a contrary conclusion is not merely a possible but a necessary inference.’ ” Goldberg v. Board of Health of Granby, 444 Mass. 627, 638 (2005), quoting Commissioner of Revenue v. Houghton Mifflin Co., 423 Mass. 42, 43 (1996). The petitioners bear the “burden of proving that the decision is invalid, and that burden is a heavy one.” Alliance I, supra, citing G. L. c. 25, § 5.
2. Good faith effort. First, the commission claims that Cape Wind did not make a good faith effort to obtain DRI approval and, thus, the siting board did not make its certificate decision in accordance with G. L. c. 164, § 69L (A) (4) (quoted in note 37, supra). The commission contends that Cape Wind did not establish good faith because it delayed the production of any evidence concerning site control until shortly before the commission’ s statutory deadline to close the public hearing, and then it agreed only to a two-week extension of the commission’s deadline to make a DRI decision. The siting board rejected this argument, finding that Cape Wind did provide “sufficient information to the Commission ... to constitute a good faith effort.” The record *691reflects that Cape Wind participated in commission meetings and hearings, responded to specific requests for information, and provided the commission with the “proof of ownership, proprietary interest or right to occupy (lease/easement) all landside locations along the proposed cable route” that it requested, or explanations as to why it could not obtain such authorizations prior to receiving DRI approval. Additionally, Cape Wind agreed to extend the DRI decision deadline by two weeks even though the Cape Cod Act did not require it to give the commission additional time. See St. 1989, c. 716, § 13 (a) (“time limit may be extended by mutual agreement with the applicant” [emphasis added]). We conclude that substantial evidence supports the siting board’s finding that Cape Wind made a good faith effort to obtain DRI approval, and we defer to that finding. See Andover v. Energy Facilities Siting Bd„ 435 Mass. 377, 391 (2001).
3. Scope of the record. The commission next claims that the siting board made its decision in violation of 980 Code Mass. Regs. § 6.03(1) (1993), by denying the commission’s motion to limit the record before the siting board to the record before the commission during the DRI review process. The cited regulation states in relevant part that “[w]hen adjudicatory findings of fact in the context of a final decision made by an agency . . . are challenged . . . review by the [siting board] of said findings shall be limited to the record presented before the agency.” Id. The siting board determined that this regulation did not apply because the commission did not conduct an adjudicatory hearing to review Cape Wind’s DRI application. Although the commission held public hearings and heard public comments, it did not take formal testimony, permit cross-examination, or make credibility determinations. Cf. School Comm. of Hudson v. Board of Educ., 448 Mass. 565, 577 (2007) (“[T]hat a public hearing was required . . . does not render the process . . . adjudicatory .... Under the statutory and regulatory scheme, the [siting] board is not required to take formal testimony, hear or cross-examine witnesses, or assess the credibility of witnesses or information submitted”). We defer to the siting board’s reasonable reading of 980 Code Mass. Regs. § 6.03(1). See Hurst v. State Ballot Law Comm’n, 428 Mass. 116, 120 (1998) (“agency’s interpretation of its own regulation is entitled to ‘substantial deference’ ”).
*6924. Section 690 findings, a. Need and cost. The petitioners all claim that the siting board failed to make certain findings required by § 690, rendering its decision in violation of statutory requirements and unsupported by substantial evidence. First, with respect to need and cost, as noted previously, § 690 (1) requires a finding of:
“the need for the facility to meet the energy requirements of the applicant’s market area taking into account wholesale bulk power or gas sales or purchases or other co-operative arrangements with other utilities and energy policies as adopted by the commonwealth” (emphasis added);
and § 690 (3) requires a finding with respect to:
“[t]he extent to which construction and operation of the facility will fail to conform with existing state and local laws, ordinances, by-laws, rules and regulations and reasonableness of exemption thereunder, if any, consistent with the implementation of the energy policies contained in this chapter to provide a necessary energy supply for the commonwealth with a minimum impact on the environment at the lowest possible cost” (emphases added).
As to § 690 (1), the commission argues that the siting board heard no evidence of need for the project to meet the energy requirements of Cape Wind’s market area; and that, rather than making findings of need and cost, the siting board “took the unprecedented position that construction of the [wind farm] conclusively establishes the ‘need’ for the [p]roject under §§ 69J and 690.” As to § 690 (3), the Alliance adds that the cost of energy supply encompasses more than just the cost of the transmission lines.
The siting board rejected the petitioners’ argument that § 690 requires it to assess the need for and cost of the wind farm, as opposed to the transmission lines. The siting board reasoned that it could not include the wind farm in a need or cost assessment due to the wind farm’s location in Federal waters and, even setting the preemption problem aside, because the 1997 Electric Restructuring Act amended G. L. c. 164 to eliminate *693considerations of need with respect to generating facilities. See G. L. c. 164, § 69JV4, inserted by St. 1997, c. 164, § 210 (“Nothing in this chapter shall be construed as requiring the [siting] board to make findings regarding the need for, the cost of, or alternative sites for a generating facility . . .”). See also G. L. c. 164, § 690V2, inserted by St. 1997, c. 164, § 223 (setting forth findings required to support siting board decision on petition pursuant to G. L. c. 164, § 69KV2, for certificate of environmental impact and public interest for generating facility and including same requirements as § 690, but not requiring finding of need for the facility).40 The siting board explained:
“It is not reasonable to assume that the Legislature intended to prohibit the [siting board] from directly assessing the need for generation facilities ... yet intended for the [siting board] to perform a ‘backdoor,’ indirect assessment of need for the generating facility when the [siting board] considers a [certificate for a transmission line. At the very least, the statute is ambiguous as to this issue, and the [s]iting [b]oard therefore exercises its discretion to interpret the statute in a manner that achieves the underlying purpose of the 1997 Electric Restructuring Act, which was to allow the marketplace, rather than a state regulatory body, to determine the need for generation facilities.”
This court has agreed with the siting board that the 1997 Electric Restructuring Act “changed the rules with respect to the manner in which the [siting] board evaluates the need for proposed energy facilities.” Alliance I, 448 Mass, at 51. Given the 1997 amendments, we agreed that “the [siting] board could no longer consider ... the need for the generating facility that the proposed transmission lines would serve.” Id. at 53. We held that the siting board had discretion to announce a new approach, under which it considers “(1) whether the ‘existing *694transmission system is inadequate to interconnect the new or expanded generator’ and (2) whether the ‘new or expanded generator is likely to be available to contribute to the regional energy supply.’ ” Id. If a generating facility lies outside the siting board’s jurisdiction, a showing for purposes of the second consideration “ ‘may be made on a case-by-case basis based on indicators of project progress (e.g., progress in permitting . . .).’ This approach is particularly appropriate if the generating facility . . . is within the jurisdiction of the United States government, and Federal agencies will be making critical decisions about its permitting.”41 Id.
Applying this approach here, the siting board looked to findings it had made in its earlier decisions on the Cape Wind transmission project under § 69J and G. L. c. 164, § 72 (§ 72), to the effect that Cape Wind had established that the existing transmission system was inadequate to support the wind farm and, thus, the transmission project was needed to contribute to the regional energy supply. Because these findings were based on the availability of the wind farm, the siting board conditioned its approval of the transmission project in its § 69J decision on Cape Wind’s submission to the siting board of copies of all permits required to build the wind farm. See Alliance I, 448 Mass, at 50, 54. As the record in the subsequent § 69K proceeding indicated no material changes with respect to the need for the transmission project, the siting board found that the project satisfied § 690 (1) and (3). We see no reason why this approach, upheld in the § 69J context, see id., should not apply as well in the §§ 69K and 690 context. In sum, we defer to the siting board’s reasonable interpretation of § 690.42
b. Environmental impact. The petitioners next argue that the *695siting board made insufficient findings under § 690 (2) and (3) with respect to the environmental impact of the transmission project. Specifically, they claim that the siting board (a) failed to find that the project will have a minimum impact on the environment; (b) improperly relied on findings made in its § 69J decision; (c) erred in failing to require Cape Wind to conduct diver surveys of eelgrass locations along the entire transmission line route and provide additional core samples to demonstrate impacts of dredging; and (d) improperly excluded evidence of the wind farm’s in-State impacts, separate from the transmission project. The claims must be rejected.
First, the commission’s premise that the siting board must find the project will have a minimum impact on the environment is not correct. Section 690 (2) requires a finding with respect to the “compatibility of the facility with considerations of environmental protection,” and § 690 (3) requires a finding that any exemption from conformance with State or local law be “consistent with the implementation of the energy policies contained in this chapter to provide a necessary energy supply for the commonwealth with a minimum impact on the environment at the lowest possible cost” (emphases added). The siting board made both of these findings. Second, as stated (see note 42, supra), the siting board properly looked to findings it had made in its §§ 69J and 72 decisions, including findings (in the § 69J decision) that “the proposed transmission lines were preferable to all alternatives with respect to environmental impacts” and that conditions to which Cape Wind agreed relating to eelgrass, protected coastal shorebirds, navigation, traffic, and historic preservation would minimize the environmental impacts of the transmission project. Like § 690, § 69J requires the siting board to consider whether a proposed facility is “consistent with the policies stated in [§ 69H],” that is, “to provide a reliable energy supply for the commonwealth with a minimum impact on the environment at the lowest possible cost.” G. L. c. 164, § 69H. “[Wjords used in one part of a statute to connote a particular meaning should be given the *696same meaning in another part of the same statute,” Commonwealth v. Burnham, 451 Mass. 517, 521 (2008), and we reject the contention that findings made in the § 69J context may have no bearing on § 690 findings. In any case, the siting board did not rely solely on its earlier decisions. It reexamined the environmental impacts of the transmission project in light of additional evidence that the parties presented during the certificate proceedings, which included the testimony of two Cape Wind experts, testimony of Alliance and commission witnesses, testimony from a DEP environmental analyst, and extensive documentary evidence.
The siting board focused its inquiry on three environmental concerns that the commission had cited in its .denial of Cape Wind’s application for DRI approval: (1) general impacts of jet-plowing for transmission cable installation; (2) impacts of cable installation on eelgrass beds43; and (3) the proposed location of a transition vault connecting the submarine and upland transmission lines in a Federal Emergency Management Agency “Velocity Zone” (FEMA V-zone) and within one hundred feet of a coastal bank. The siting board found that it had given each issue extensive consideration in its prior decisions; each issue had also received a favorable review by DEP and by EOEEA in the MEPA process; and no information presented during the § 69K certificate proceedings called the siting board’s earlier determinations into question. We defer to these findings, which are supported by substantial evidence in the record.44 See Andover v. Energy Facilities Siting Bd., 435 Mass, at 386, 388.
As to jet-plowing, the commission had determined that this method of installation implicated minimum performance standard (MPS) 2.2.3.6, a standard set forth in the commission’s RPP that prohibits new dredging unless needed to provide substantial *697public benefit and no feasible alternative exists. The commission had concluded that more core samples were necessary to determine the impact of jet-plowing on eelgrass and shellfish resources. Cape Wind had argued to the commission, and offered expert testimony to the siting board, that jet-plowing is necessary to install the transmission lines and has fewer environmental impacts than other installation methods. Witnesses further stated that Cape Wind had taken nineteen core samples in State waters to measure the impact of jet-plowing, a sample size deemed adequate by DEP and other permitting agencies. Cape Wind also pointed the siting board to monitoring and mitigation measures it has proposed to undertake. After assessing this issue in light of its earlier proceedings and the evidence adduced in the § 69K certificate proceedings, the siting board found jet-plowing consistent with considerations of environmental protection, a finding supported by substantial evidence. There was no error in the siting board’s decision not to require Cape Wind to conduct additional core sampling.
As for eelgrass, in the DRI proceeding the commission had cited MPS 2.23.1, which requires that development have “no significant adverse direct or indirect effect on eelgrass beds, unless there is no feasible alternative and the project is necessary to accomplish a public benefit,” and had asked Cape Wind to perform diver surveys of the entire transmission line route within State waters, in addition to the diver surveys Cape Wind had already conducted in Lewis Bay. The siting board did not find that eel-grass concerns made construction and operation of the transmission lines inconsistent with environmental protection. The siting board reasoned that Cape Wind had conducted side-scan sonar surveys of the entire transmission fine route, which according to Cape Wind experts reduced the potential for mapping errors, and had also conducted site-specific visual inspection by divers. The siting board also noted that Cape Wind has agreed to extensive monitoring and mitigation efforts to protect eelgrass, including additional diver surveys if additional eelgrass beds are identified. The findings are supported by substantial evidence.
Finally, with respect to the transmission vault, the commission had pointed to MPS 2.2.2.1, which prohibits development in a FEMA V-zone, an area subject to hundred year storms. While the commission permits construction of water-dependent structures in *698a FEMA V-zone absent a feasible alternative, it had determined in its decision that the vault did not meet the RPP definition of a “water-dependent use.” The commission had also cited MPS 2.2. 2.4, which prohibits nonwater-dependent development within one hundred feet of a coastal bank. The commission had recommended that Cape Wind relocate the vault 225 feet landward to comply with both MPSs. The siting board, however, found that the costs of moving the vault — including increased noise, traffic, and reduced reliability — outweighed any benefits associated with avoiding the FEMA V-zone and coastal bank buffer. This finding also is supported by substantial evidence.
c. Conformance with existing law. The petitioners make a related claim that the siting board made inadequate findings to satisfy the “reasonableness of exemption” standard in § 690 (3). The Alliance and Barnstable argue that “reasonableness” should be construed broadly to authorize and require review of the in-State impacts of Cape Wind’s entire enterprise and to preclude the siting board from relying on earlier decisions in determining whether the standard was met. However, the term “reasonableness” does not trump the exclusivity of Federal review over the wind farm itself, as earlier discussed.
Additionally, the siting board properly relied on its findings in the §§ 69J and 72 proceedings where § 690 (3) directs it to review reasonableness “consistent with the implementation of the energy policies contained in this chapter.” See note 36, supra. The siting board fully addressed the reasonableness standard and articulated support for its conclusions.
C. Water-dependent use regulation. Finally, the Alliance challenges the validity of a regulation promulgated by DEP on October 3, 2008, 310 Code Mass. Regs. § 9.12(2)(b)(10) (water-dependent use regulation, or regulation),45 as contrary to DEP’s relevant governing statutes, c. 91, §§ 1, 2, 14, and 18, *699violative of DEP’s responsibilities under the public trust doctrine, and arbitrary.
*698“(2) [DEP] shall determine a use to be water-dependent upon a finding that said use requires direct access to or location in tidal or inland waters, and therefore cannot be located away from said waters. ...(b) [DEP] shall find to be water-dependent-industrial the following uses: ... 10. infrastructure facilities used to deliver electricity .. . services to the public from an offshore facility located outside the Commonwealth.”
*699We review briefly certain statutory and regulatory provisions pertinent to the Alliance’s challenge. General Laws c. 91, § 2, directs DEP, in issuing licenses pursuant to that chapter, to “protect the interests of the commonwealth” in the tidelands. Section 14 of c. 91 thereafter states that “[ejxcept as provided in [c. 91, § 18, relating to nonwater-dependent uses], no structures or fill may be licensed on . . . commonwealth tidelands unless such structures or fill are necessary to accommodate a water dependent use; provided that for commonwealth tidelands said structures . . . shall also serve a proper public purpose and that said purpose shall provide a greater public benefit than public detriment to the rights of the public in said lands.” To help implement this section, DEP promulgated 310 Code Mass. Regs. § 9.31(2)(a) (1996), a regulation that creates a rebuttable presumption that a “water-dependent use” serves a proper public purpose that provides a greater benefit than detriment to the rights of the public.46 In this case, based on the water-dependent use regulation, DEP deemed Cape Wind’s proposed transmission lines water dependent and found nothing to rebut the proper public purpose presumption established by § 9.31(2)(a). The siting board incorporated this finding into its certificate decision.
“A highly deferential standard of review governs a facial challenge to regulations promulgated by a government agency.” Massachusetts Fed’n of Teachers v. Board of Educ., 436 Mass. 763, 771 (2002). One who challenges a regulation’s validity “must prove ‘that the regulation is illegal, arbitrary, or capricious.’ ” Id., quoting Borden, Inc. v. Commissioner of Pub. Health, 388 Mass. *700707, 722, cert, denied sub nom. Formaldehyde Inst., Inc. v. Fre-chette, 464 U.S. 936 (1983). We apply all rational presumptions in favor of validity, and cannot declare a regulation void “unless its provisions cannot by any reasonable construction be interpreted in harmony with the legislative mandate.” Massachusetts Fed’n of Teachers v. Board of Educ., supra, quoting Consolidated Cigar Corp. v. Department of Pub. Health, 372 Mass. 844, 855 (1977).
*699“(2) Proper Public Purpose Requirement. No license or permit shall be issued by [DEP] for any project on tidelands . . . unless said project serves a proper public purpose which provides greater benefit than detriment to the rights of the public in said lands. In applying 310 [Code Mass. Regs. § ] 9.31(2), [DEP] shall act in accordance with the following provisions.
“(a) Water-Dependent Use Projects. [DEP] shall presume 310 [Code Mass. Regs. § ] 9.31 (2) is met if the project is a water-dependent use project.”
*700The Alliance has not met its burden to establish invalidity. It claims that the water-dependent use regulation violates the governing statute, c. 91, because c. 91, § 1, defines “water-dependent uses” as “those uses and facilities which require direct access to, or location in, marine or tidal waters and which therefore cannot be located inland” (emphasis added), and wind farms can be located inland. But the water-dependent use regulation applies solely to “infrastructure facilities used to deliver electricity . . . from an offshore facility” (emphasis added), not to the offshore facility itself.
The premise underlying all the Alliance’s challenges to the water-dependent use regulation is that c. 91, §§ 2, 14, and 18, do not permit DEP to define as “water-dependent” —■ and thus presumptively serving a proper public purpose — any use of an infrastructure facility associated with a generating facility unless DEP also evaluates the impacts of the generating facility itself. Because the premise is flawed, the Alliance’s claims fail.
As we have discussed in relation to the siting board, if a generating facility is located offshore in Federal waters, a State agency such as DEP has no jurisdiction over the facility under c. 91 or otherwise, and is not in a position to assess its allegedly adverse impacts on the Commonwealth. But it is also obvious that if such a generating facility receives the necessary Federal permits and is constructed, an “infrastructure facility” such as the transmission lines must have a “direct . . . location in . . . tidal waters,” c. 91, § 1, in order to perform its function of delivering electricity.47 Accordingly, it was rational for DEP to adopt a regulation that focuses solely on the infrastructure facility used to transmit electricity from the offshore and out-of-*701jurisdiction generating facility, and it was rational for DEP to define such an infrastructure facility as “water-dependent.” See Brackett v. Civil Service Comm’n, 447 Mass. 233, 254 (2006). The Alliance has not shown that the water-dependent use regulation is arbitrary, irrational, or contrary to c. 91. The regulation’s validity must be upheld. See id. at 254-255.
Conclusion. Case no. SJC-10596 is remanded to the county court. Judgment is to enter affirming the decision of the Energy Facilities Siting Board and declaring that 310 Code Mass. Regs. § 9.12 (2)(b)(10) is a valid regulation. In case no. SJC-10578, the judgment of dismissal is affirmed.
So ordered.
The background information is taken from the administrative record of the siting board’s proceeding to consider Cape Wind’s petition and application for a “certificate of environmental impact and public interest” (certificate, or § 69K certificate) pursuant to G. L. c. 164, § 69K (§ 69K).
Review of the petition to build and operate two 115 kilovolt underground and undersea electric transmission cables or lines (transmission project, or transmission lines) under the Massachusetts Environmental Protection Act (MEPA) occurred jointly with Federal review by the Minerals Management Service (MMS) under the National Environmental Policy Act (NEPA). NEPA review covered the offshore wind-powered energy generating facility (wind farm) itself, in addition to the transmission project. MEPA review did not. The Secretary of the Executive Office of Energy and Environmental Affairs (EOEEA) gave this explanation in the final environmental impact report:
The siting board is “an independent review board established within the department of telecommunications and energy and charged by the Legislature with administering the provisions contained in G. L. c. 164, §§ 69H through 69Q” in order to fulfil its “governing mandate, set forth in § 69H ... to ‘provide a reliable energy supply for the commonwealth with a minimum impact on the environment at the lowest possible cost.’ ” Alliance to Protect Nantucket Sound, Inc. v. Energy Facilities Siting Bd., 448 Mass. 45, 46-47 (2006) (Alliance I).
General Laws c. 164, § 691 (§ 691), states in relevant part: “No applicant shall commence construction of [an electric] facility . . . unless a petition for approval of construction of that facility has been approved by the [siting] board .... In addition, no state agency shall issue a construction permit for any such facility unless the petition to construct such facility has been approved by the [siting] board . . . .”
The definition of “[fjacility” in G. L. c. 164, § 69G, includes “a new electric transmission line having a design rating of [sixty-nine] kilovolts or more and which is one mile or more in length on a new transmission corridor.”
At the same time that Cape Wind sought § 691 approval in 2002, it also petitioned the Department of Public Utilities (DPU) under G. L. c. 164, § 72 (§ 72), for a determination that the transmission lines were necessary, would serve the public convenience, and were consistent with the public interest. The DPU chairman referred the § 72 petition to the siting board for review, to be consolidated with Cape Wind’s § 691 petition. The siting board’s presiding officer ultimately bifurcated the petitions because a § 72 decision could not be made until the completion of MEPA review. In May, 2008, the siting board issued its § 72 decision, finding the transmission project necessary and in the public interest and convenience pursuant to § 72, approving minor changes to the transmission project as it had been originally approved in the siting board’s § 69J decision in 2005, and granting a three-year extension to begin construction.
The commission argued before the siting board that its denial of Cape Wind’s development of regional impact (DRI) application was procedural only, a denial without prejudice due to lack of information. The siting board rejected this contention, concluding that the commission’s decision represented a final denial of the DRI application on its merits. The commission does not challenge this determination before us.
The commission argued before the siting board that it had only denied the DRI approval without prejudice due to lack of information, rather than an affirmative finding of noncompliance with DRI standards. The siting board rejected this contention, and the commission does not raise it here.
General Laws c. 164, § 69K, states in relevant part: “Any electric, gas or oil company which proposes to construct or operate facilities in the commonwealth may petition the [siting] board for a certificate of environmental impact and public interest with respect to such facility. The [siting] board shall consider such petition providing: ... the facility cannot be constructed due to any disapprovals, conditions or denials by a state or local agency or body, except with respect to any lands or interests therein, excluding public ways, owned or managed by any state agency or local government.”
In October, 2008, Cape Wind filed with DEP an application for a tidelands license pursuant to G. L. c. 91, § 14, and 310 Code Mass. Regs. §§ 9.00 (2008). This replaced and superseded the application Cape Wind had filed with DEP on December 13, 2004. DEP did not act on Cape Wind’s 2004 application because the MEPA process had not yet been completed. On December 22, 2008, after public hearing, DEP issued a draft license and written determination that the proposed transmission project satisfied the requirements of G. L. c. 91 (c. 91). DEP found that the project, as infrastructure to be used to deliver electricity from an offshore facility outside the Commonwealth, qualified as a water-dependent industrial use of tidelands under 310 Code Mass. Regs. § 9.12(2)(b)(10). DEP further found that the “project serves a proper public purpose which provides greater public benefit than detriment to the public’s rights in said tidelands” and “preserves public rights of access to [the] tidelands for fishing, fowling, navigation and the natural derivatives thereof.” DEP conditioned the draft license on receipt of all Federal, State, and local approvals, including State and local permits obtained in the form of a § 69K certificate. On January 9, 2009, the Alliance to Protect Nantucket Sound, Inc. (Alliance), filed a claim for an administrative adjudicatory hearing on the DEP draft license under c. 91, § 18, and 310 Code Mass. Regs. § 9.17. On July 10, 2009, DEP stayed further proceedings pending decision in this case.
The commission and the Alliance moved to limit the certificate proceeding to the record the commission had considered during its own DRI review. They also moved to dismiss on several grounds. The siting board’s presiding officer denied the motions. The presiding officer granted Cape Wind’s motion to limit the scope of the certificate proceeding to facilities located within the Commonwealth, that is, the transmission lines, as opposed the wind farm or its instate impacts. We discuss the issues raised by these various motions infra.
The Alliance and Barnstable offered prefiled direct testimony addressing instate impacts of the wind farm, which the presiding officer excluded pursuant to the earlier ruling with respect to the scope of the certificate proceedings. See note 15, supra.
Barnstable and the commission sought declaratory relief under G. L. c. 231 A, concerning an alleged conflict between the Cape Cod Act, St. 1989, § 716, and the siting board’s enabling statute, G. L. c. 164, §§ 69G-69Q (siting board statute). A Superior Court judge dismissed the complaint for failure to exhaust administrative remedies. Barnstable and the commission appealed, and we granted their application for direct appellate review. See note 4, supra. The parties agree that the remaining live issues from the Superior Court action are before this court in the appeal from the siting board decision pursuant to G. L. c. 164, § 69P, and G. L. c. 25, § 5. Accordingly, we do not consider further Barnstable’s appeal from the Superior Court judgment in this opinion.
The stipulations were made solely for the purposes of the declaratory *672judgment claims challenging the validity of 310 Code Mass. Regs. § 9.12(2)(b)(10), discussed infra. There is no contention of failure to exhaust administrative remedies with respect to this claim.
In the petitions filed in the county court pursuant to G. L. c. 164, § 69P, and G. L. c. 25, § 5, Barnstable and the Alliance had included two counts for declaratory relief, one concerning the DEP regulation and the second relating to whether Federal law preempts State agencies from considering in-State impacts of the wind farm, whether the siting board has the authority to issue the equivalent of a tidelands license under c. 91, and whether the siting board has the authority to override St. 1989, c. 716, the Cape Cod Act. In their briefs, Barnstable and the Alliance have appropriately argued the substance of their second count as challenges to the validity of the siting board’s decision and have not made any argument as to why they should be the subject of separate declaratory relief. We consider any claim to that effect waived. Mass. R. A. P. 16 (a) (4), as amended, 367 Mass. 921 (1975).
For purposes of reviewing the operation of the two statutes together, we assume that the commission qualifies as a “local agency or body” or “local government” as those terms are used in § 69K and G. L. c. 164, § 69L. The correctness of this assumption is considered infra.
We refer to the final portion of the second sentence in § 69K’s first *674paragraph, which provides that the siting board “shall” consider an electric company’s petition for a certificate if “the facility cannot be constructed due to any . . . denials by a state or local agency or body.”
The petitioners make much of the fact that the Legislature specified in § 12 (/) of the Cape Cod Act that for purposes of comprehensive permits governed by G. L. c. 40B, the commission was to be considered a “local board,” but included no similar provision stating that the commission was a “state or local agency or body” for purposes of § 69K; their argument is that if the Legislature had intended to subordinate the commission to the siting board, it would have explicitly so provided. But as the siting board observed, the opposite inference is equally valid: the Legislature could have, but did not, specifically exempt the commission’s DRI decisions from the siting board’s jurisdiction when it enacted the Cape Cod Act.
The petitioners advance a separate but related argument that the Barn-stable Home Rule Charter, St. 1988, c. 163, like the Cape Cod Act, effectively supersedes the siting board statute as a later enacted and more specific statute. Specifically, they claim that § 69K limits the siting board’s override authority to “disapprovals, conditions or denials,” language that does not extend to the “repeal” of the regional policy plan (RPP), a county ordinance enacted under the Barnstable Home Rule Charter, and “repeal” is what the petitioners state *675occurred here. We disagree. The siting board’s § 69K certificate in effect overruled the commission’s denial of Cape Wind’s DRI application; there was no “repeal” of the RPP. Nor have the petitioners pointed to any particular provision in the Barnstable Home Rule Charter that they consider to be directly inconsistent with § 69K.
In its original form, the clause of § 69K’s first paragraph in question here read: “or the facility cannot be constructed due to any disapprovals, conditions or denials by local governments.” G. L. c. 164, § 69K, inserted by St. 1973, c. 1232, § 1. In 1976, the term “local governments” was replaced by the phrase “a state or local agency or body.” G. L. c. 164, § 69K, as amended through St. 1976, c. 468, § 6. The parties have not referred us to any legislative history, and we have found none, that appears to shed direct light on this change. Nonetheless, it is reasonable to assume from the language itself that its purpose was principally to add the word “State” to the phrase, and that the Legislature then substituted “agency or body” for “governments” in the phrase “a state or local agency or body” to reflect that State agencies or bodies were now included. Our understanding is supported by the fact that throughout § 69K in its original form, see St. 1973, c. 1232, § 1, and currently, the Legislature has consistently referred to permits of State and local agencies or local governments as a group (see § 69K, first, second, and fourth pars.), suggesting that the 1976 amendment was an attempt to correct this one nonconforming reference to “local governments” only.
Tidelands are a “broad but single category of the estuarine complex comprising the shore and submerged lands lying between mean high water and the seaward boundary of the Commonwealth.” Final Report: A Study of the Law Pertaining to the Tidelands of Massachusetts, 1971 House Doc. No. 4932, at 15. Chapter 91, § 1, defines “[t]idelands” as “present and former submerged lands and tidal flats lying below the mean high water mark.” The section further separates “[tjidelands” into “Commonwealth tidelands” and “[pjrivate tidelands.” “Commonwealth tidelands” are defined as “tidelands held by the commonwealth in trust for the benefit of the public or held by another party by license or grant of the commonwealth subject to an express or implied condition subsequent that it be used for a public purpose.” G. L. c. 91, § 1. The portions of Lewis Bay and Nantucket Sound within the Commonwealth’s territorial jurisdiction are Commonwealth tidelands.
There is overlap between the definition of the term “facility” as it is used in § 69K (see G. L. c. 164, § 69G, which sets out the definition, quoted in note 9, supra); and “structure” as used in c. 91, § 14 (see c. 91, § 1, which defines the term). The transmission lines that Cape Wind seeks to construct qualify both as a “facility” for purposes of § 69K and as a “structure” under c. 91, §§ 14 and 18.
As previously discussed, Cape Wind initially sought a c. 91 license directly from DEP, and in December, 2008, DEP issued a draft license and written determination that the transmission project met the requirements of c. 91. See note 14, supra. The siting board incorporated DEP’s findings into its certificate *679decision and included the equivalent of a tidelands license in the certificate it granted. DEP expressly stated that it had no objection.
General Laws c. 164, § 690 (3), authorizes the siting board in certain instances to issue a § 69K certificate that would not require the certificate holder to conform fully “with existing state and local laws, ordinances, bylaws, rules and regulations.” See note 36, infra. The Commonwealth’s public trust obligations exist independently of such State and local laws and other regulatory measures. See Moot v. Department of Envtl. Protection, 448 Mass. 340, 347 (2007) (Moot I), citing Fafard v. Conservation Comm’n of Barnstable, 432 Mass. 194, 200 n.ll (2000) (Fafard) (“the Commonwealth’s authority and obligations under [G. L. c. 91] are not precisely coextensive with its authority and obligations under the public trust doctrine”). We do not read § 690 (3) as a delegation of authority to the siting board effectively to exempt a facility from otherwise applicable requirements of the public trust doctrine. Rather, in any case where public trust obligations are in play because a c. 91 tidelands license is at issue, those obligations must be fully met by the applicant seeking a certificate in the absence of further legislative action. Cf. Moot I, supra at 350, 352-353 (under public trust doctrine, DEP could not, without specific legislative authorization, adopt regulation exempting filled landlocked tidelands from c. 91’s licensing requirements). Cf. also Arno v. Commonwealth, ante 434, 453 n.21 (2010) (land registration proceedings concerning plaintiff’s parcel of filled tidelands could not have effect of relinquishing public trust rights in that parcel absent specific legislative authorization).
While not directly bearing on the delegation question discussed in the text, additional sections of the siting board statute reflect the Legislature’s interest in having DEP, the agency to which the Legislature generally has granted authority to issue such licenses, play a role in the siting board’s decision where a c. 91 tidelands license is in issue. Thus, G. L. c. 164, §§ 69L and 69N, read together, define the “parties in interest” in any certificate proceeding to include, among others, any person or entity that the siting board permits to intervene. In the present case, DEP was an intervener in the § 69K proceeding concerning Cape Wind, and fully participated in that proceeding. Moreover, in G. L. c. 164, § 69H, as amended through St. 2007, c. 19, § 37, the Legislature has designated the Secretary of EOEEA, the Executive Office in which DEP resides, as the chair of the siting board itself, and the commissioner of DEP as one of the siting board’s nine members. We view these provisions as steps taken by the Legislature to facilitate the siting board’s obligation to address DEP’s statutory and regulatory mandate — including the protection of public trust rights — when, as in this case, they are implicated by a § 69K certificate application.
In Moot I, 448 Mass, at 347, 352-353, we held that DEP exceeded its authority under G. L. c. 91, § 18, by promulgating a regulation exempting filled landlocked tidelands from c. 91’s licensing requirements. “By exempting filled ‘landlocked’ tidelands from the statute’s licensing requirements, [DEP was] relinquishing all control over the use of the filled land . . . without legislative authorization, effectively relinquishing all public rights that the Legislature has mandated be preserved through the licensing requirements." Id. at 350. See Moot v. Department of Envtl. Protection, 456 Mass. 309, 310 (2010) (Moot II). Here, there has been no relinquishment or extinguishment of the public’s rights in the tidelands at issue.
We agree with the Chief Justice, see post at 703, that an express statement from the Legislature is necessary both to relinquish public rights in tidelands and to delegate authority to administer public trust rights and duties. See, e.g., Arno v. Commonwealth, supra at 438 n.7, 453 n.21. The decisions of this court, however, have recognized a difference between a legislative delegation of authority to administer public trust rights and duties through regulation or use of tidelands subject to conditions, and a permanent relinquishment of the public’s rights in tidelands. The latter can only happen where the Legislature has undertaken specific steps and made explicit findings to signal its intent to relinquish. Compare Fafard, 432 Mass, at 199 n.10 (“The Commonwealth may delegate, and has delegated, its authority to preserve and regulate Commonwealth tidelands to State agencies or municipalities”), and Boston Waterfront Dev. Corp. v. Commonwealth, 378 Mass. 629, 649 (1979) (wharf-ing statutes granting landowners fee simple title to certain Commonwealth tidelands “subject to the condition subsequent that it be used for the public purpose for which it was granted”), with Opinions of the Justices, 383 Mass. 895, 901-905 (1981) (setting forth steps Legislature must take to “abandon, release, or extinguish the public interest in submerged land” and noting that “Boston Waterfront . . . concerned the consequences of the Lewis Wharf statutes, . . . which did not undertake by their express terms to transfer all the Commonwealth’s or the public’s interests in the disputed land”). Cf. Moot II, supra at 313-315 (legislation enacted after Moot I did not relinquish public rights in landlocked tidelands but permissibly exempted them from c. 91 licensing scheme; court therefore rejected plaintiffs’ claim that legislation exceeded Legislature’s authority by effectively extinguishing public trust rights without explicit findings required by Opinions of the Justices, supra). While it is clear from our case law what steps the Legislature must take to relinquish the public’s rights in tidelands, see Opinions of the Justices, supra, our cases addressing delegation of authority to regulate tidelands, and in doing so to administer public trust rights and duties, have said only that such delegation must be express. See Commonwealth v. Charlestown, 1 Pick. 180, 184-185 (1822). And the statutory provisions effecting this type of delegation have generally been broadly phrased, offering few specific directives to the designated *681agency or official on how to exercise the authority given them. See Fafard, supra, and statutes cited. As we have discussed, our view is that in § 69K, the Legislature has expressly delegated to the siting board the authority to grant a revocable c. 91 license to use the tidelands at issue, and encompassed in that delegation is the authority, and obligation, to administer public trust rights and duties.
The petitioners mention, in particular, impacts of the wind farm’s turbine generators on “state waters, air space, lands, and public safety,” alleging that *683the wind farm will cause harm to navigation, aviation, fisheries, birds, and water quality, as well as create an increased set of risks relating to public safety and environmental damage that a town such as Barnstable will be forced to confront.
This point is reinforced by the fact that since the passage of the 1997 Restructuring Act, St. 1997, c. 164, which amended the siting board statute in several respects, the Legislature has mandated that a proposed “generating facility” (a term that describes the wind farm) be reviewed by the siting board separately from a “facility” (the term that describes the transmission lines). See, e.g., G. L. c. 164, §§ 69J¼, 69K½, 69L½, 690½, inserted by St. 1997, c. 164, §§ 210, 214, 216, and 223, respectively.
Despite the fact that our public trust doctrine relating to, inter alia, Commonwealth tidelands is “an age-old concept with ancient roots,” Trio Algarvio, Inc. v. Commissioner of the Dep’t of Envtl. Protection, 440 Mass. 94, 97 (2003), the United States Supreme Court has made it clear “that the United States enjoys exclusive title in the lands underlying the sea [below the low water mark], regardless of a state’s historical claims to the waters off its coast.” Ten Taxpayer Citizens Group v. Cape Wind Assoc., LLC, 373 F.3d 183, 188 (1st Cir. 2004), cert, denied, 543 U.S. 1121 (2005), citing United States v. California, 332 U.S. 19, 29-39 (1947); United States v. Louisiana, 339 U.S. 699, 705-706 (1950); United States v. Texas, 339 U.S. 707, 719-720 (1950); and United States v. Maine, 420 U.S. 515, 522 (1975). Massachusetts, like all other coastal States, has title to the three-mile margin of seabed off its coast only because, in 1953, Congress passed the Submerged Lands Act of 1953, 43 U.S.C. §§ 1301 et seq. (2006), which granted this right.
The legislative history of the siting board statute indicates an early recognition of the limits Federal law places on the scope of the siting board’s authority. The Legislature enacted the siting board statute in 1973. St. 1973, c. 1232. The following year, it amended a savings clause in the 1973 statute, see id. at § 6, to include the following language: “This act shall not apply to any matter over which any agency, department, or instrumentality of the federal government has exclusive jurisdiction.” St. 1974, c. 852, § 21. The Legislature reiterated this limitation in St. 1992, c. 141, § 54.
A Federal statute expressly provides for review and comment on Federal permitting decisions relating to a project that affects use of land, water, or *687natural resources of a State’s coastal zone. See 16 U.S.C. § 1456(c)(3)(A) (2006). In the Commonwealth, the Coastal Zone Management Office (CZM) conducts the review authorized by this statute.
General Laws c. 164, § 690, states, in relevant part:
“The [siting] board shall make its decision [on a petition for a certificate] in writing and shall include therein its findings and opinions with respect to the following:
“(1) the need for the facility to meet the energy requirements of the applicant’s market area taking into account wholesale bulk power or gas sales or purchases or other co-operative arrangements with other utilities and energy policies as adopted by the commonwealth;
“(2) the compatibility of the facility with considerations of environmental protection, public health and public safety;
“(3) [t]he extent to which construction and operation of the facility will fail to conform with existing state and local laws, ordinances, bylaws, rules and regulations and reasonableness of exemption thereunder, if any, consistent with the implementation of the energy policies con*689tained in this chapter to provide a necessary energy supply for the commonwealth with a minimum impact on the environment at the lowest possible cost; and
“(4) the public interest, convenience and necessity requiring construction and operation of the facility.”
General Laws c. 164, § 69L (A), states, in relevant part:
Without DRI approval, Cape Wind could not obtain wetlands orders of conditions from the conservation commissions of Barnstable and Yarmouth, or road opening permits from each of those towns’ departments of public works. The siting board found it “appropriate to avoid further permitting delay by including the otherwise unobtainable local permits in [the] Certificate, as opposed to requiring [Cape Wind] to undertake an entire de novo permitting process” after receiving the certificate, noting that it had comprehensively reviewed and approved the project three times in seven years and that the relevant local permitting entities had participated actively in the certificate proceedings.
The certificate, as previously discussed, incorporated DEP’s written determination that Cape Wind satisfied the requirements for a c. 91 license. The certificate also included a so-called § 401 certification that DEP had issued pursuant to § 401 of the Federal Clean Water Act, 33 U.S.C. §§ 1251 et seq. (2006), and the Massachusetts Clean Waters Act, G. L. c. 21, §§ 26 et seq.; a highway access permit that the Massachusetts Highway Department had issued; and a license for use and occupancy authorizing the crossing of a rail line that the Executive Office of Transportation and Public Works had issued.
The 1997 Electric Restructuring Act also amended G. L. c. 164, § 69H, as appearing in St. 1992, c. 141, § 9, changing the siting board’s mandate from providing a “necessary energy supply” to providing “a reliable energy supply” and adding that “the [siting] board shall review only the environmental impacts of generating facilities, consistent with the . . . policy of allowing market forces to determine the need for and cost of such facilities.” St. 1997, c. 164, § 204.
We reasoned that an “attempt by the [siting] board to predict the decisions of Federal agencies would constitute an exercise in administrative inefficiency and waste the time and effort of the siting board and the applicants.” Alliance I, 448 Mass, at 53.
We address briefly the petitioners’ general claim that the siting board erred by relying on findings of need made in its earlier proceedings. Nothing in the siting board statute or its regulations requires the siting board to conduct, in a certificate proceeding under G. L. c. §§ 69K-69P, a de novo review of issues such as need or cost that it has addressed in a § 69J proceeding. Cf. City Council of Agawam v. Energy Facilities Siting Bd., 437 Mass. 821, 829 (2002) (“A certificate proceeding conducted pursuant to [G. L. c. 164, *695§ 69K‘/2,] is not a vehicle for the relitigation of issues that have already been fully and fairly determined” in § 69J proceedings). In the present case, the record reflects that the siting board considered additional evidence and found no material changes with respect to the need for the transmission project.
Eelgrass grows in intertidal and subtidal areas, providing cover and habitat for shellfish and fish.
We reject the commission’s unsupported claim that Cape Wind’s experts were not qualified to testify on these matters and improperly relied on hearsay documents. The record contains substantial evidence of the experts’ qualifications, and hearsay is admissible in administrative proceedings. Box Pond Ass’n v. Energy Facilities Siting Bd., 435 Mass. 408, 418 (2001), citing School Comm. of Brockton v. Massachusetts Comm’n Against Discrimination, 423 Mass. 7, 15 (1996).
TitIe 310 Code Mass. Regs. § 9.12(2)(b)(10) (2008) provides:
Title 310 Code Mass. Regs. § 9.31(2)(a) (1996) provides:
The wording of 310 Code Mass. Regs. § 9.12(2)(b)(10) appears to link a determination that the infrastructure facility is covered by that regulation, and therefore “water-dependent,” with the generating facility’s existence and corresponding receipt of all necessary Federal permits. This is consistent with the *701approach that DEP, as well as the siting board, took in this case insofar as both conditioned the c. 91 license on Cape Wind’s receipt of all necessary Federal (and State) permits for the construction and operation of the wind farm itself.