The issue raised by the instant cause is whether the rate increase levied against the utility’s Columbus customers is reasonable and lawful. More specifically, the question is whether there is sufficient probative evidence in the record to support the commission’s choice of an allocation formula and its valuation of the utility’s “used and useful” property.
This court’s standard! of review for a determination by the Public Utilities Commission is set forth in R. C. 4903.13.
R. C. 4903.13 provides:
“A final order made by the Public Utilities Commission shall be reversed, vacated, or modified by the supreme court on appeal, if, upon consideration of the record, such court is of the opinion that such order was unlawful or unreasonable.”
Under the “unlawful or unreasonable” standard specified in R. C. 4903.13, this court will not reverse or modify an opinion and order of the Public Utilities Commission where the record contains sufficient probative evidence to show that the commission’s determination is not manifestly against the weight of the evidence and is not so clearly unsupported by the record as to show misapprehension, mistake or willful disregard of duty. Delphos v. Pub. Util. Comm. (1940), 137 Ohio St. 422, 424; Cleveland Elec. Illuminating Co. v. Pub. Util. Comm. (1975), 42 Ohio St. 2d 403, paragraph eight of the syllabus; and General Motors Corp. v. Pub. Util. Comm. (1976), 47 Ohio St. 2d 58, paragraph two of the syllabus.
*105The two commission practices challenged by the city in the instant cause are its adoption of an allocation formula based on a non-verifiable assumption and its equation of “used and useful” property with property listed on the utility’s books as “in service” property. There is sufficient probative evidence in the record to show that neither practice was manifestly against the weight of the evidence and to support, as reasonable and lawful, the commission’s final order.
The commission adopted an allocation formula based, in part, on the non-verifiable assumption that the relationship between the average and peak demands of city and non-city residents is the same.2 The expert who employed that formula in the utility’s application testified, in effect, that the formula’s reliance on the assumption did not make the formula unfair to Columbus residents, A staff expert concurred in that conclusion, and the staff report, which was admitted in evidence, concluded that the allocation factors were “generally reasonable and appropriate.” Civen the above evidence in support of the commission’s choice of an allocation formula, we find that choice to be reasonable and lawful.
There is also sufficient probative evidence to support as reasonable and lawful the commission’s reliance on utility records of property “in service” to determine the value of utility property “used and useful.” At the hearing, the utility’s controller testified that the utility believed that the property listed on its books as “in service” was “used and useful.” In addition, the staff report concluded that there were “no significant discrepancies” between the company’s property records and “the actual physical property.”3 The commission’s reliance on utility records in the instant cause was reasonable and lawful.
*106The practices underpinning the commission’s final order being reasonable and lawful, the order is affirmed.
Order affirmed.
Herbert, W. Brown, Sweeney and Holmes, JJ., concur. Celebrezzb, C. J., P. Brown and Locher, JJ., dissent.It was impossible for the commission to determine with certainty whether the relationship between the average and peak demands of Columbus and non-Columbus customers is the same because most Columbus and jurisdictional utility customers do not have demand meters.
The staff report, standing alone, would have been sufficient to support the commission’s equation of “in service” property with “used and useful” property. See Akron v. Pub. Util. Comm. (1978), 55 Ohio *106St. 2d 155, 158. However, in these days of spiraling utility rates and the increasingly desperate plight of those living on fixed incomes, it is to be hoped that utilities will support their applications for increased rates with more than the minimal probative evidence required under the “unlawful or unreasonable” standard.