Water Warning: The Spokane River is Gradually Disappearing

August 27th, 2009

Inlander, William Stimson

Spokane has been measuring the flow of water under the Monroe Street Bridge for over 100 years, and for over 100 years the level of that flow has been falling.

In 1900, even a dry summer still saw a presentable plunge of about 1,500 cubic feet per second going past the old wooden bridge. Today a dry summer produces only a third of that — the relative trickle we see in August.

The gradual drying of the river is, surprisingly, a relatively recent discovery. People knew, of course, that the river canyon looked parched in the summer months. But particularly dry years were always traceable to some immediate explanation: less snowfall, hotter weather, new pumpers and the like. And then there were occasionally wet summers to blur the picture.

Measurements kept since 1891 of the “7-Day Low Flow” of the river — the stretch of seven days each summer when the least water is coming down — gives a very reliable picture of what’s going on with the river. When John Covert and other hydrologists with the Washington Department of Ecology stepped back and saw all the measurements of a century as one chart, an unsettling pattern was clear. The lines bounced up and down each decade, all right, but overall they sloped relentlessly downward.

What’s happening to the water? Over the last century, it’s been trimmed away for various human uses.

The wild mountain river that pioneers found disappeared with the construction of the Post Falls Dam in 1906. No one thought anything of it at the time because the dam still allowed plenty of water to flow down river.

Then in 1941, the emergency of World War II required raising the level of Lake Coeur d’Alene to facilitate the floating of logs needed for the war effort. It turned out that raising the lake level just 1.5 feet kept a great deal of water out of the Spokane River basin. The change was supposed to be temporary, but people built docks at the new level and consequently lobbied to keep the lake where it was. There’s no chance of reversing it now.

In the meantime, agriculture grew up in the Spokane Valley and began pumping the aquifer, one of the sources of river water.

Then came the insatiable lawns of urban sprawl. The average amount of water each person in Spokane uses increases five-fold in the summer because of soaking and over-soaking lawns. Because water is cheap here, Spokane uses more water per capita than almost any city in the country. Spokane people even water at mid-day, when much of the water poured on grass goes straight up in evaporation.

While this water comes from the aquifer, which eventually recharges itself, the river is indirectly affected because some of its flow comes from the aquifer.

For the average Spokanite, Covert concedes, the lowering of the river is — for the moment — mostly an aesthetic problem: We don’t get to see the plunging water in the summer.

But as he points out, it’s more serious for other species that rely on the river water. A shallower river is warmer, and warmer water stresses the plant life and insects at the bottom of the food chain. That stress works its way up from insects to fish and hawks and all other life dependent upon open water. For land animals, it’s harder to find the tiny ponds and ribbon streams that are their water supply in the summer.

Spokane is exceptional in that it is better off than most places in the world. Seven southwest states (including California, where most of the nation’s fruit is grown) are facing absolute water shortages. Towns as close as Pullman and Walla Walla are lowering their aquifers, a situation that cannot continue for long.

When Covert and other water specialists (such as Geoff Glenn, a pollution analyst for the city of Spokane) talk about the charts and trends, you can detect a tone of urgency and even dread. If Spokane, a city with a relatively small population, surrounded by snow packs, rivers and streams, and underlain by a gigantic aquifer, notices diminishing water, it does not bode well for the future. Says Covert: “It’s the canary in the mine shaft.”

William Stimson is director of the Journalism Program at Eastern Washington University.