Nissen Reservoir Goes On-Line

July 1, 2008

Christopher Schall
Conservation Research Specialist

Nissen reservoir, one of CCWCD’s most recent construction projects, delivered its first water early this April.

Located between Greeley and Kersey along the South Platte River, Nissen is an underground, sand/gravel filled water storage facility that utilizes an impermeable geological feature as a base, and a man made bentonite-soil mixture as a surrounding wall.

“The best way to understand Nissen is to think of a sponge in a cup, where the sponge is the sand and gravel holding the water and the cup is the site’s impermeable surroundings” explains Justin Bieri, CCWCD Information Resources Manager.

In action, Nissen stores CCWCD’s water supplies until needed to offset member well pumping. “Nissen has been a huge help this year,” says Ruthanne Schaffer, CCWCD water accountant. “Being underground, Nissen doesn’t suffer evaporation losses like other facilities, and since it’s so close to the river it’s really efficient at moving water around, there are virtually no transmission losses.”

One of the greatest features of Nissen is the ability to measure and control water around the site. Nissen uses dewatering pumps, remotely controlled gates and the nearby Plumb Ditch to fill and drain. “The inlet structure is constructed to take up to 75 cubic feet per second, and currently it can store up to 950 acre-feet of water, but once the site’s been mined of sand and gravel it will store 3,000 acre-feet” says Randy Ray, CCWCD Operations Manager and Nissen project lead.

CCWCD staff has taken great care to test and monitor the facility for two years before full use, ensuring stellar performance. The slurry wall received State Engineer approval in spring of 2007. “We’re definitely going to use Nissen a lot this year” Says Ruthann.