Summertime ups and downs in reservoir management

July 3, 2018

Blazing summertime temperatures are driving fun-loving recreationists to the cooling waters of regional lakes and rivers. Nevada Irrigation District (NID)’s nine reservoirs are an especially big draw for folks who boat, swim, kayak, fish, etc.

Water levels in these reservoirs are constantly changing this time of year, as NID water managers adjust levels to meet different water needs. While late spring snowmelt helped to fill the reservoirs, water demand is highest during the dry months of summer. Stored water is released to irrigate crops, provide drinking water (after treatment), generate hydroelectric power and support ecosystems with environmental flows in the rivers.

“It’s a complicated process to make sure there’s the ideal balance of water in the reservoirs,” said Sue Sindt, NID’s Water Resources Superintendent. “It requires daily monitoring of the system, knowledge of the system’s capabilities, customer demand patterns, and utilization of hydrographic and customer data.”

“Reservoir releases are monitored daily along with flows in the canals to ensure that we are being responsive to customer demand, but not being wasteful,” Sindt said.

This summer, NID reservoir levels are at healthy levels. As of the end of-June, the District’s storage was at 250,800 acre-feet, which was 93 percent of capacity and 113 percent of average for the date (an acre-foot is about 326,000 gallons, or enough water to cover an acre of land 1-foot deep).

At the end of this year’s rainy season, total precipitation at Bowman Lake was 68.63 inches, which is very close to the average total of 69.64 inches. However, while the total precipitation was close to average, the amount that fell as snow was well below average. The April 1 snow water content was 21.98 inches; only 66 percent of average. The runoff from the snowmelt has been about 75 percent of average.

“Overall nearly every reservoir filled this year,’ Sindt said. “However; with less than average runoff the reservoirs did not stay full very long and the withdrawal from storage started a little sooner than an average year.”

“This will affect the amount of storage we will end the season with and have to carry into next year. At this point it is anticipated that the end of season storage will be near average,” she added.

NID’s water supply system is a “store and release” system that depend on reservoirs to retain snowmelt and seasonal rains for release during dry irrigation seasons. Careful reservoir management and operation is essential to capture the maximum amount of runoff, minimize spillage and, also, ensure there is sufficient area available to accommodate flows from spring snowmelt and storm events.

Keep track of reservoir storage and water levels on NID’s River and Lake Data webpage.

 

NID Reservoirs

Reservoir – Elevation – Capacity (in acre-feet)

Foothill Division:

Rollins 2,171 ft. (65,988 af)

Scotts Flat 3,075 ft. (48,547 af)

Combie 1,600 ft. (5,555 af)

Mountain Division:

Jackson Meadows 6,036 ft. (69,205 af)

Bowman 5,563 ft. (68,510 af)

French Lake 6,835 ft. (13,940 af)

Faucherie 6,123 ft. (3,980 af)

Sawmill 5,863 ft. (3,030 af)

Jackson Lake 6,598 ft. (1,330 af)

 

Total storage capacity: 280,085 acre-feet

 

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