USGS groundwater study expected to spur progress

YAKIMA, Wash. -- "Now what?" might be the operative query with the release of a lengthy and complicated groundwater study that concludes what has long been suspected -- pumping from wells is affecting existing surface water rights in the Yakima River Basin.

What will happen as a result of the 12-year, $6 million U.S. Geological Survey study isn't yet in full focus.

But this much is certain: Offsetting new uses by purchasing a share of a senior surface water right will be part of the answer, state Department of Ecology officials say.

Another potential outcome is the completion of new water storage -- still years down the road -- that could allow for new uses.

"Some people feel clearly we can close the basin (to new wells)," said Tom Tebb, Ecology's regional director in Yakima. "We don't think that is responsible. We need to have dialogue with local governments, the Bureau of Reclamation and the Yakama Nation, to strive for consensus to frame the challenge."

"It will take time for people to digest this monumental piece of science," Tebb said, referring to the study. "The next few months will be about that dialogue."

The study, commissioned as part of a settlement of disputes over new water wells and their impact on existing water rights, includes a sophisticated computer model that can determine what impact a new water well will have on current nearby users and the Yakima River.

The model breaks the basin into 1,000 square-foot grids. The model can be used to determine what impact a withdrawal will have on surface water based on data collected during the study.

U.S. Geological Survey scientists will describe the study and the model at a public workshop sometime this month. A specific date will be announced soon.

A final report on the study, which was issued last month, concludes that pumping has hurt existing surface rights, including deep pumping from basalt aquifers well below the surface.

Domestic well pumping also has had a small, yet detectable, impact on surface flows.

Surface water in the Yakima River has been spoken for since 1905 by the Yakama Nation and the federal Bureau of Reclamation, meaning any subsequent well use takes water that belongs to someone else. Both the nation and the bureau, who participated in the settlement, want Ecology to halt the draw on surface water by well users who started drawing after 1905.

Matt Ely, a USGS hydrogeologist who was part of the study team, said the model is based on conditions in effect in 2001 and can provide general information about the groundwater system.

"We can take the base case and add a well or simulate drought conditions. There is a host of things you can play with," Ely said. "You can add a well and look at the changes in streamflow associated with that well."

The study concluded that as of 2001, the last year of the 42 years the study reviewed, pumping from wells created a cumulative 194 cubic feet per second decline in the flows in the Yakima River at Richland.

At Union Gap, south of Yakima, the reduction was 75 cubic feet per second.

The location is important because just south of Union Gap at Parker, the Bureau of Reclamation must maintain at least 300 cubic feet per second of flow to sustain fish. The requirement is contained in a 1994 federal law that also provided funding to help farmers become more efficient in their water use.

A model scenario that looked solely at pumping from domestic wells -- homes that are not required to obtain a state permit -- amounted to about 10 cubic feet per second.

Domestic wells have been at the heart of a controversy in upper Kittitas County where Ecology closed the area to new wells more than two years ago out of concern growth was harming surface water rights and streamflows.

The Department of Ecology plans to use the model to make decisions about the nearly 900 pending applications for new wells pending.

The study concludes that had those applications been approved, the additional draw on the Yakima River would have been another 88 cubic feet per second of water or more than 280 cubic feet per second when added to the current decline of 194 cubic feet per second.

Tebb said the agency, the bureau, the Yakama Nation and local governments will need time to understand what the model can do.

"There will be an assessment of what the study said, how that relates to where we are in the current time frame and the work we will do to drive our decision-making," he said.

* David Lester can be reached at 509-577-7674 or dlester@yakimaherald.com.