The result of groundwater pumping is obvious in Nevada, too
We read with great interest and a sense of déja` vu Steve Stuebner's article on the Big Lost River being dewatered due to groundwater pumping (HCN, 2/20/95).
Déja` vu because here in Nevada we are dealing with the imminent collapse of a desert lake ecosystem, and groundwater pumping for agriculture is playing an important role in this basin's problems.
Walker Lake is located in sparsely populated Mineral County in west-central Nevada. Mineral County's economy is tied to the lake with many dollars coming from fishermen, boaters and RV'ers. The lake is startling when first viewed, as are all desert lakes: a vast blue gem, five miles wide and 14 miles long, with the steep cliffs of the Wassuk Range seeming to rise right out of the water to the west. Even more startling is that the lake supports what was until recently a trophy Lahontan cutthroat trout fishery. It is an "endangered species of lake" according to Alex Horne, a University of California limnologist, one of only a handful of deep desert lakes supporting salmonid fishes in the world.
But all of this appears not enough to save Walker Lake's fishery from collapse in the next few years. The lake's problems are deceptively simple: It is a terminal lake, the final destination of waters from the Walker River. But little or no water ever reaches it.
Upstream are vast fields of alfalfa, pasture and other crops farmed in Bridgeport, Antelope, Smith, and Mason valleys and on the Walker River Paiute Reservation. They explain the empty sand channel leading to the lake because irrigators use all the water in the system - an average of 250,000 to 300,000 acre-feet per year - and there are plenty of water rights beyond what the system yields in any given year. The overallocation of the river system, completely legal and governed by an adjudicated federal court decree, leaves no water for the lake.
Added to this is groundwater pumping which supplements river diversions for agriculture. Over the past eight years of drought, the aquifer has been drawn down as much as 45 feet in one valley and 85 feet in another. The small amount of river water that isn't diverted then flows underground to fill this deficit. Hydrological studies indicate that 700,000 acre-feet of water have been lost to the river during drought years to recharge the over-pumped aquifer.
After about 100 years of surface overallocation and 30 years of groundwater pumping, Walker Lake is now at the brink of losing a fishery that in past years rewarded fishermen with 30-pound trout. As volume decreases, total dissolved solids increase to the extent that trout and the food chain upon which they depend will soon be unable to survive. In addition, migratory birds - loons, pelicans, ibis, plovers, curlews and many others - will lose a critical food and rest stop during their long migrations through the arid Great Basin.
What we are seeing in the Walker River and Snake River basins and elsewhere in the West is a failure to recognize that, in many instances, surface and groundwater resources are the same resource. We need to recognize that groundwater pumping in near-river aquifers is a surface diversion of future flow that is detrimental to surface water irrigators and the environment. We need cooperation from water users and water managers at all levels - local, state and federal - to resolve these complex Western water issues.
Unless we start managing rivers and groundwater together and accepting the fact that actions taken on one eventually impact the other, more Walker Lake and Big Lost River scenarios will come to pass.
Ann Kersten, Susan Lynn, Tom Myers
Susan Lynn is executive director and Ann Kersten research coordinator at Public Resource Associates. Tom Myers is a graduate student in hydrology at the University of Nevada, Reno.