concurring. I concur only in the result because the majority holds that the commission, in deciding technically sophisticated and complex matters, can rely upon nonexpert evidence to satisfy the substantial evidence rule.1
*318Section 5 of the Easton Inland Wetlands and Watercourses Regulations2 requires the commission to take into consideration, and make findings with respect to, the environmental impact of the proposed action, including the “nature of any materials to be . . . deposited and the effect on flood control water supply and quality . . . .” Id., § 5.1.4. As it pertains to the present case, the commission’s determination involved decisions on technically sophisticated and complex matters. See Feinson v. Conservation Commission, 180 Conn. 421, 426-27, 429 A.2d 910 (1980).
Feinson makes clear that a lay commission acts without substantial evidence when it relies on its own knowledge and experience concerning technically complex issues. Id., 427-29. It follows that if the lay commission cannot rely upon its own knowledge and experience in such cases, neither can it rely upon nonexpert evidence from others. Connecticut Natural Gas Corporation v. PUCA, 183 Conn. 128, 142, 439 A.2d 282 (1981); see State v. McClary, 207 Conn. 233, 243, 541 A.2d 96 (1988); Jaffe v. State Department of Health, 135 Conn. 339, 349, 64 A.2d 330 (1949). “[T]he commission may not reject an expert’s testimony on a ‘technically sophisticated and complex’ issue that ‘goes beyond “the ordinary knowledge and experience” of the trier of fact,’ unless there is expert testimony available to the commission that will support its decision.” T. Tondro, Connecticut Land Use Regulation (1983 Supp.), p. 101.
The majority’s reliance on Huck v. Inland Wetlands & Watercourses Agency, 203 Conn. 525, 545, 525 A.2d 940 (1987), is misplaced. The court in Huck went to great lengths to describe the expert evidence supporting the agency’s denial of the application, which *319included the report of two agency experts that showed a “potential of pollution.” Id., 549. The director of the town’s environmental health office, although favoring the application, conceded the proposed activity could cause pollution of the lake because of the siltation problem. Id., 545. The court held that this expert evidence, taken with the deficiencies in the testimony presented by the plaintiff’s expert, “furnish[es] a fair basis for the agency’s stated view on its denial.” Id., 545.
Recently, this court, relying on Feinson and Huck, held that although an administrative agency need not “believe any of the witnesses, including expert witnesses . . . it must not disregard the only expert evidence available on the issue when the commission members lack their own expertise or knowledge.” (Citation omitted.) Tanner v. Conservation Commission, 15 Conn. App. 336, 341, 544 A.2d 258 (1988). Any other rule would allow the agency to permit, as well as to prohibit, activities affecting inland wetlands and watercourses without substantial evidence of a competent nature. This could defeat the beneficient purposes of the Inland Wetlands and Watercourses Act, which is to protect this “irreplaceable but fragile natural resource with which the citizens of this state have been endowed.” General Statutes § 22a-36.
Nevertheless, nonexpert knowledge and testimony are relevant and may aid in determining the underlying facts in order to evaluate the expert’s opinion. See C. Tait, Connecticut Evidence § 7.16.8 (2d Ed.). For example, in Huck, the general grade of the slope of the subject property to the lake became a relevant factor. The commissioner’s nonexpert knowledge was used to evaluate the expert’s opinion. He disclosed at the hearing that the grade was at least forty-five [degrees] and that “ 'merely walking on that slope created a disturbance and caused things to roll into the lake.’ ” Huck v. Inland Wetlands & Watercourses Agency, supra, 545 *320n.16. Determinations of the nontechnical facts and opinion within the knowledge of a lay person, however, must be distinguished from determinations of technically complex facts and opinions, which can come only from an expert.
Unfortunately, the majority gets bogged down on what constitutes expert evidence. Such evidence comes from not only environmental scientists, engineers and the like, but also from those who gained their expertise from practical experience. Bryan v. Branford, 50 Conn. 246, 248 (1882).
In the present case, the decision of the commission was supported by the expert testimony of Les Warren, the soil erosion and sediment control officer of the commission. He recommended that the application be denied because the proposal would adversely affect the floodplain as a result of the depositing of 830 cubic yards of fill in the area adjacent to the Mill River.3
The plaintiffs argue that the soil erosion and sediment control officer’s opinion should be discounted because the record does not show that he has any expertise in this area. The simple answer is that the plaintiffs, though given a full opportunity to challenge both Warren’s qualifications as well as his opinion, chose not to do so. Moreover, there is a “presumption that public officials acting officially properly performed their *321duties.” Aczas v. Stuart Heights, Inc., 154 Conn. 54, 58-59, 221 A.2d 589 (1966). This encompasses the presumption that the public official is qualified in the field wherein his or her official duties lie until the contrary is shown. State v. Main, 69 Conn. 123, 140, 37 A. 80 (1897).
I concur in the result that the commission’s reasons for denying the plaintiffs’ application were supported by substantial evidence and in the finding of no error.
The “substantial evidence rule is similar to the ‘sufficiency of the evidence’ standard applied in judicial review of jury verdicts, and evidence is sufficient to sustain an agency finding if it affords ‘a substantial basis of fact from which the fact in issue can be reasonably inferred .... [I]t must be enough to justify, if the trial were to a jury, a refusal to direct a verdict when the conclusion sought to be drawn from it is one of fact for the jury.’ ” Lawrence v. Kozlowski, 171 Conn. 705, 713, 372 A.2d 110 (1976), cert. denied, 431 U.S. 969, 97 S. Ct. 2930, 53 L. Ed. 2d 1066 (1977); Huck v. Inland Wetlands & Watercourses Agency, 203 Conn. 525, 541, 525 A.2d 940 (1987).
The defendant is the duly designated municipal commission entrusted with the enforcement of the Inland Wetlands and Watercourses Act, General Statutes §§ 22a-36 et seq.
The majority points out the failure of the plaintiffs to indicate on the record that they would accept the technical changes in the proposed construction suggested by Donald Ballou, the professional engineer retained by the commission, who found that the proposed construction would not be detrimental to the environment. Surely, the majority does not mean to suggest that the failure of the plaintiffs to indicate their acceptance of these changes on the record at the hearing would constitute grounds to deny the application. That would not be fair or practical as the commission has authority to grant the application upon “such terms, conditions, limitations or modifications of the regulated activity, designed to carry out the policy of sections 22a-36 to 22a-45, inclusive.” General Statutes § 22a-42a (d).