A valley north of Reno that’s seen thousands of new homes in recent decades has much more available water than state records indicate, according to developers seeking to build more houses.
The developers are citing research they funded to respond to a moratorium on new groundwater pumping Nevada’s State Engineer imposed on the Cold Spring hydrographic basin in December.
The state engineer imposed the moratorium over concerns the amount of water rights already approved exceeds the basin’s “perennial yield.”
“The moratorium … was directed at the review and approval of new subdivision maps to allow our office to truly understand the water availability in the basin,” said Micheline Fairbank, deputy administrator of the Nevada Division of water Resources.
The developers presented their findings Thursday during a hearing called to review evidence. Their research indicated the perennial yield is significantly higher than the state’s estimate.
“If pumping was over the perennial yield … we would see a continual decline in water levels especially in areas of active pumping and we don’t see that,” said hydrogeology expert Justin Huntington, who conducted research for Heinz Holdco, a company seeking to build thousands of homes in the Cold Spring basin, including the proposed Stonegate development which would rely on a mix of pumped and imported water.
Perennial yield is the amount of water people can pump without resulting in long-term aquifer depletion.
It varies depending on how quickly nature replenishes the groundwater supply in an area where people are pumping. When pumping is less than or equal to the amount of water flowing into a basin, the basin’s supply can be considered secure.
State law requires developers to show their developments won’t push consumptive use of water higher than the perennial yield of the basin where they wish to build.
“It is used as a guideline for the appropriation of water,” Tim Wilson, Nevada’s state engineer, said Friday during a separate presentation to lawmakers. “Our goal is to keep the consumptive use of groundwater within or below the perennial yield of the basin.”
At the time of the Cold Spring moratorium, Department of Conservation and Natural Resources Director Bradley Crowell said the amount of approved water rights already exceeded the state’s estimates of the amount of water that naturally flows into basin aquifers.
The basin, located at Reno’s northern fringe and home to the Cold Springs community, has seen the number of homes increase from about 500 in 1979 to more than 3,000 today.
The state’s perennial yield estimate was about 500 acre feet annually, which is roughly enough water for 1,000 homes.
If the state’s estimate is accurate, it means the Cold Spring basin is among the 106 out of 256 basins in Nevada where the quantity of water rights on paper exceeds the quantity of available water.
“It doesn’t sound like an area that has a lot of water for additional development,” Crowell said in December.
But Heinz Holdco, which has plans to build thousands more homes, says the state estimates are flawed.
The hearing on Thursday was their opportunity to present technical evidence to support their assertions.
The hearing lasted more than six hours and was largely devoted to highly technical details.
It mostly consisted of experts presenting findings that indicate the true perennial yield is much higher than the state’s estimate, which is based on research that includes studies from 1967 and 1981.
And while Huntington and others said much of the earlier research was solid, it overlooked important factors that influence how much water is available for pumping.
Huntington estimated the area’s perennial yield is 1,830 acre feet, more than three times higher than the state’s estimate.
“This perennial yield is sufficient to meet the needs of the current commitment in the basin,” said Debbie Leonard, an attorney for Heinz Holdco.
In addition to the higher perennial yield estimate, Huntington said the groundwater supply gets another boost the state estimate doesn’t account for in the form of treated wastewater. That is, water that’s pumped and used in homes gets returned to the ground after treatment
“We are infiltrating that effluent, there is reuse and it should be considered in figuring out what the sustainable yield is,” Huntington said.
Additionally, Heinz has plans to use a pipeline to import water from California’s Honey Lake basin to supply its planned Stonegate project.
Recharge from the imported water could further increase the amount of water that could be sustainably pumped.
State officials will consider the evidence from Heinz and other sources in making a decision on the basin’s true perennial yield, Fairbank said.
“Whether the perennial yield is adjusted will be based upon the Division’s review of the totality of the data,” she said.
During his presentation about water issues to the Legislature’s Interim Public Lands Committee on Friday, Wilson acknowledged new evidence could justify an update to the state’s perennial yield estimate.
“We did get a significant study submitted to us that may indicate it is off by quite a bit,” Wilson said.
Benjamin Spillman covers the outdoors and environment in Northern Nevada, from backcountry skiing in the Sierra to the latest from Lake Tahoe’s ecosystem. Support his work by subscribing to RGJ.com right here.
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