Big aquifer whets thirst of water suppliers
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Some Eastside water districts and Seattle Public Utilities believe the 26-square-mile Snoqualmie Aquifer could dramatically increase the regional-water supply, keeping faucets flowing even in a drought year like this one.
However, any attempt to remove ground water is likely to meet resistance from environmentalists and the state Ecology Department, which is wary about any withdrawals that might reduce the amount of water available to seep into salmon streams.
To overcome this, proponents have designed a unique system: Pump the water directly into the Snoqualmie River, where it will tumble over Snoqualmie Falls and flow for 35 miles before being diverted at the regional Tolt Pipeline near Duvall.
The river becomes part of the municipal water-conveyance network. And while it moves downstream, aquifer water could increase flow volumes by 10 percent, helping the region meet its federal Endangered Species Act obligation to nurture fish runs.
"This is one of the new style of resource projects that supplies water for both people and fish," said Bob Pancoast, executive director of the East King County Regional Water Association, a consortium of 13 water districts.
Seattle and the Eastside association have quietly spent a decade and $1 million to study the subterranean water flows and drill test wells near the Snoqualmie.
Water shortages in existing suburban wells, dryouts in the north fork of Issaquah Creek and the worst winter snowpack on record have re-energized the proposed $78 million project in the minds of suburban water-district officials, according to Pancoast.
Two to five years from now, the association hopes to build its wells and begin pumping into the river to prove the project is harmless to fish runs. In five to 10 years, drinking water would be diverted and filtered for public consumption.
Ice-age gift
The Snoqualmie Aquifer is a gift from the last ice age, when a glacier from the Cascade Range collided with the massive Vashon Ice Sheet, which descended from Canada and formed Vashon Island.
Each glacier pushed gravel into the Snoqualmie Valley, and those glacial moraines accumulated in lowlands that wrap around Mount Si.
The legacy of that event some 14,000 years ago can be seen today. Two gravel embankments more than 1,000 feet thick rise above the middle fork of the river.
Soil samples show the commingling of black volcanic gravel from Canada with the lighter, speckled Cascade gravels.
The underground layer of gravel has been likened to a sponge or a bathtub full of pebbles because of its ability to absorb immense volumes of water.
"It's like finding another Chester Morse Lake, but underground," said Bob Anderson, a hydrogeologist working with the water purveyors, referring to Seattle's main reservoir in the upper Cedar River.
The potential for water storage was first recognized in 1991 by geologist Geoff Clayton of Redmond.
Since then, seven test wells have pumped, and Anderson estimates the aquifer could be pumped for 100 days while draining the water table only a couple of feet.
The area is nourished by more than eight feet of rainfall a year, so its winter downpours - which tend to saturate the ground or run off - would restock the aquifer, advocates say.
Proponents think the aquifer is less vulnerable to the effects of global warming than are reservoirs, which rely on mountain snowpack. Even if snowfall declines, precipitation would still arrive as rain that refreshes the aquifer, Pancoast says.
Golder Associates, the engineering consultant for this project, is studying a similar strategy in the Methow Valley of Central Washington, where irrigation water was turned off this year to ensure better stream flows for salmon.
Other sources, other options
The Snoqualmie aquifer is one of 16 new water sources being studied to serve the Puget Sound region and its 3.1 million inhabitants. Other options include drawing water from the Green River or from Lake Tapps outside Tacoma.
Environmentalists from American Rivers, the Sierra Club and Trout Unlimited know little about the Snoqualmie project, but they are skeptical. One question: If aquifer water is diverted at Duvall, would that disrupt flows to the lower reaches of the Snoqualmie and Snohomish rivers?
Pancoast said the water volumes removed at the pipeline would be adjusted based on river conditions, so there would never be less flow downstream than nature would provide.
And because water volumes above Duvall increase, less of the riverbed would dry out in late summer, so fish should have an easier time migrating, he said.
Some people challenge the wisdom of exploiting new sources of water.
A more intensive conservation effort might delay the need for additional water supplies by 50 or 100 years, says Rob Caldwell, executive director of the Center for Environmental Law and Policy.
"I would much rather see the lawns in Woodinville turn to gold than replumb all of our aquifers," he said.
In any case, the project is not assured of happening. Water rights are becoming more difficult to obtain, and the Ecology Department would require an environmental-impact statement, public hearings and tests beforehand.
Since 1995, the state has rejected approximately 70 smaller water-rights applications in the Snoqualmie-Snohomish basin, which still sustains vigorous runs of wild coho.