The 14-year Southwest drought is slowly reducing the quantity of hydroelectric power that local governments and electric utilities in California, Nevada and Arizona draw from Hoover Dam.

Power users in Nevada and California, some of whom worry about higher rates from lower amounts of hydropower, fear the decline in Hoover power may be even more rapid next year because of increasing water shortages in the Colorado River.

"This is the worst 14-year drought period in the last hundred years," Larry Walkoviak, director of the Bureau of Reclamation's Upper Colorado Region, said in a statement.

Hoover Dam, which created Lake Mead near the southern tip of Nevada in the 1930s, has a maximum generating capacity of 2,074 MW. But the dam was generating only 1,753 MW this past May, according to the Colorado River Commission of Nevada.

Jayne Harkins, CRC executive director, attributed Hoover's decreasing hydropower to falling water levels in Lake Mead and the need to shut off turbines that start vibrating as the lake level drops.

The lake's elevation was 1,106 feet on Aug. 21, down from 1,214 feet at year-end 1999, the year the drought began, according to the U.S. Bureau of Reclamation, which operates Hoover Dam.

The bureau on Aug. 16 predicted Lake Mead's elevation will drop another eight feet during the fiscal year starting Oct. 1, 2013, because of a decision to reduce the quantity of water released at Glen Canyon Dam northwest of Hoover.

Next fiscal year, the bureau said it will release only 7.48 million acre-feet of water through Glen Canyon Dam, down from 8.23 MAF projected for the current year. The move, the result of U.S. Interior Department drought regulations, will mark the first time the bureau has restricted water releases from Lake Powell since the 1960s, according to the Southern Nevada Water Authority. Bureau officials hope snowfall in the upper Colorado River area will be heavy enough to reverse the trend next year.

The Los Angeles Department of Water & Power already has been getting less energy and capacity from Hoover Dam because of the drought, LADWP spokeswoman Michelle Vargas told Energy Prospects West.

"We've had to rely on other power resources to meet our load and deliver power to our customers," Vargas said.

LADWP has the right to power from 491 MW of capacity at Hoover, but the LADWP 2012 integrated resource plan shows only 468 MW of "net dependable capability" from Hoover, citing lower lake levels that resulted from the drought.

While LADWP is allocated a 15.4-percent share of firm energy from Hoover Dam, the Metropolitan Water District of Southern California gets 28.5 percent of the firm energy, according to the bureau.

Metropolitan uses 1 million to 1.2 million MWh of electricity from Hoover to pump water from Lake Mead to 16 cities and municipal water districts, said Jon Lambeck, Metropolitan manager of power operations and planning.

Hoover provides an average of 50 percent of the energy Metropolitan consumes pumping water from Lake Mead through an aqueduct to Southern California, Lambeck said. However, Hoover accounted for 80 percent in 2010, when Metropolitan drew less water from Lake Mead.

Lambeck attributed the variation in power generation to the level of the lake and the quantity of water released through the dams, but he said improved hydropower efficiency at the dams has helped over the years.

The cost of energy is one of many factors Metropolitan uses to determine the wholesale rate it will charge local governments and water districts for water, he said.

The Western Area Power Administration sets the price of Hoover Dam power based on costs, and the 2.13-cent/kWh current price represents a primary benefit for the electric utilities and local and state agencies that get allocations from Hoover Dam.

The price drops to 2.02 cents/kWh next fiscal year, according to WAPA.

The Southern Nevada Water Authority, however, is starting to analyze whether the cost of hydropower will increase as the quantity of power produced at the dams decreases, said SNWA spokesman J.C. Davis.

Also, the agency wonders if a reduction in overall power supplies from decreasing hydropower will cause wholesale power prices to increase, he said.

SNWA and the Las Vegas Valley Water District obtain about 10 MW of their 200 MW peak summer loads from the Hoover and Glen Canyon dams, Davis said.

Valley Electric Association, a cooperative based in Pahrump, Nev., receives 6.7 percent of its power from Hoover Dam, VEA Executive Vice President Susan Fisher said in an email.

The expected decline in power from Hoover Dam will not significantly affect the co-op's rates, she said. If Hoover Dam power supplies are reduced next year, Valley Electric said it will study costs of alternatives and cover any shortfall with power purchases on the day-ahead, bi-weekly, bi-monthly or longer-term markets, coupled with power-price hedges. The cooperative does not own any power plants.

About 18 percent of VEA's power comes from hydro, including Hoover and other dams along the Colorado River.

Nevada Power, which does business as NV Energy, received about 459,000 MWh of generation from Hoover Dam during 2012, about 1.5 percent of total energy used by its customers in southern Nevada, company spokesman Mark Severts said in an email.

Hoover's varying power generation does not measurably affect NV Energy's energy-supply strategy and has little effect on rates, Severts said.

Nevada gets 23.4 percent of the energy from Hoover Dam; Arizona, 19 percent; and Southern California Edison, 5.5 percent. Some entities, such as Edison and Metropolitan, have direct contracts for power, but in Arizona and Nevada, state agencies get the allocation and then divide the power among utilities and local governments.

Boulder City, Nev., and the California cities of Anaheim, Azusa, Banning, Burbank, Colton, Glendale, Pasadena, Riverside and Vernon get smaller allocations.

- John Edwards

© 2013 Energy NewsData

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