Facing unexpected decreases in its water supply, a Sacramento Valley water district has turned on five additional wells, sparking the ire of a local conservation organization concerned about groundwater levels.

The Glenn-Colusa Irrigation District will pump up to 1,650 acre-feet in 30 days to supplement water supplies. The district filed an exemption from the California Environmental Quality Act allowed by Gov. Jerry Brown's emergency drought declaration.

In doing so, the district is allowed to begin pumping from the five wells without completing an environmental impact study, although the district is taking steps to complete a study for the longer-term operations of the wells, said Thad Bettner, general manager.

The exemption did not sit will with AquAlliance, a Chico-based conservation organization.

Executive Director Barbara Vlamis said the district is "knowingly straining water supplies and tapping an aquifer already in extreme distress."

Vlamis said AquAlliance will review all of its legal options.

Bettner countered that the relatively small amount of water pumped over a short period of time will have no impact on groundwater levels. He said the 1,650 acre-feet the district could pump is a small percentage of the 800,000 acre-feet pumped from the ground in the area each year.

A botched temperature forecast for Shasta Lake is at the root of the conflict. The forecast model used to plan summer releases from the reservoir miscalculated the temperature of the water in the lake. As a result, releases into the Sacramento River were reduced to save the cold water necessary to stave off a massive die-off of endangered Chinook salmon.

Flows in the Sacramento River, diverted by farmers and irrigation districts, are estimated to be about 1,300 to 1,700 cubic feet per second less than what was originally planned, Bettner said.

"We're at a point now where the river elevations are probably the lowest they have ever been, and it's making it hard for settlement contractors to physically divert water from the river," Bettner said.

But Vlamis said the situation does not constitute an emergency and is something the district should have prepared for.

"This is a serious period, and we have to be more conservative," Vlamis said. "The groundwater levels are going down, and the district is turning to groundwater for water sales and also regular operations."

The five wells, between 700 and 1,000 feet deep, are in northern Glenn County along the Sacramento River. Groundwater levels have declined by as much as 15 feet in the area in the past decade, according to monitoring wells operated by the Department of Water Resources.

To the west of the five wells is an area that has seen the highest decline in groundwater levels in the northern Sacramento Valley. In this area, south of Orland, water levels have dropped up to 112 feet in the last 10 years, including declines of up to 50 feet from 2013-14, according to the DWR data.

The science of underground aquifers is still not fully understood, but Bettner said they haven't heard any concerns about the district's plans affecting cities or growers who rely on groundwater to the west.

Bettner defended the district's decision to start pumping groundwater, saying it was only necessary once it became clear the temperatures in Shasta Lake were going to impact releases into the Sacramento River.

"We fought pretty hard this year to try and maximize the amount of surface we did get, with the whole idea of trying to pump a minimal amount of groundwater," Bettner said. "If we didn't have this new operations plan, we would continue to divert water from the river."

CONTACT reporter Andrew Creasey at 749-4780 and on Twitter @AD_Creasey.

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