While Utahns wilt in summer heat and farmers fight a drought, the state's coal-fired electrical utilities are basking in higher revenues as demand for electricity has hit record levels.

"The heat started very heavy and very early and during June we hit all-time records for power demand on the system usually set in July," Utah Power & Light Co. spokesman John Ward said.A June 24 peak demand of about 2584 megawatts, topped the record peak of 2484 megawatts set in 1984.

Air conditioning among residential customers and irrigation pumps of agricultural ratepayers are the major source of increased demand, Ward said.

But the increased demand has not overtaxed UP&L's system, which is suffering from a costly 300 megawatt surplus. More demand just soaks up the surplus and improves UP&L's financial picture.

"Revenues are up and will continue with the hot summer," Ward said.

But improved efficiency is a mixed blessing for Utah's other coal-fired generator, Deseret Generation & Transmission.

"We certainly are looking at selling all of our excess capacity, but the drought is a concern for the economic condition of our agricultural customers," DG&T spokesman Ken Fisher said.

DG&T, which serves 30 municipally-owned power systems and four rural electric cooperatives, has been running at full capacity for two months because of increased demand.

Both DG&T and UP&L said most of their capacity has gone to its customers, but further surplus has been sold on the wholesale market to water starved hydroelectric utilities in the Northwest.

"We usually buy inexpensive hydro power in the Northwest and sell it to the Southwest, but for the first time in several years the flow has reversed," Ward said.

UP&L is selling power generated during off- peak hours, which is less expensive to produce and thereby results in a larger profit margin. Ward said UP&L estimated $8 million in revenues from off system sales during 1988 and it has already surpassed that mark.

Profits from off-system sales go into a regulated Energy Balancing Account and are applied periodically to UP&L's rates.

"The revenues don't go to our bottom line, but they do keep rates down, which makes us more competitive," Ward said.

DG&T said its energy sales to outside hydro producers are up 60 million kilowatt hours.

Utah's other coal-fired generator, the Intermountain Power Project near Delta, hasn't had its demand impacted by the heat wave because IPP's entire capacity was already purchased by southern California communities.

Despite estimates that show coal production should be up to accommodate the increase in electrical demand, Utah coal producers haven't reported an increase.

The National Coal Association released revised production estimates for 1988 this week, setting coal production at 926 million tons, 9 million tons more than last year. In its mid-year forecast, the association's economic committee also said domestic consumption of 932 million tons, including imported coal, would exceed last year's record by 15 million tons.

But Utah coal producers have not experienced a surge in demand since the heat has only soaked up Utah utilities' existing excess capacity, and UP&L operates its own coal mines.