Effects of Climate Change on Municipal Water Supplies

The Washington Department of Ecology's report on the economic impacts of climate change are inconclusive about the effects on municipal water supplies in eastern Washington. While no changes in total annual precipitation are expected, more will fall as rain during the winter months. This is due to an expected 2 F increase in average annual temperatures by 2020. By 2040, the average temperature increase is expected to be 3 F.

This will mean snowpack will melt earlier in the spring, which will increase the amount of water flowing into rivers and streams during the winter and early spring, but flows will decrease in the summer months.

Spokane, and much of eastern Washington, relies heavily on aquifers for the water supply. The study points out that the changes in snowpack melting will affect groundwater recharge, which is how the aquifers replenish. But the study stops short of any estimates as to the potential impact that it will have.

Spokane's Water Department website describes the Spokane Valley-Rathdrum Prairie Aquifer (commonly called the Rathdrum-Spokane Aquifer) as one of the most productive aquifers in the United States, with a total volume of about 10 tillion gallons.

The aquifer covers 332 square miles from eastern Washington to the Bitterroot Mountains, where considerably more precipitation falls (about 70 inches per year compared with about 17 inches in Spokane).

Since the Department of Ecology study only measured the impacts in Washington state, I am concerned the principal source of water for the Rathdrum-Spokane Aquifer was left out of the study.

Cook Agronomy Farm

The class took a trip to the Cook Agronomy Farm Tuesday to discuss the Climate Friendly Farming project with Dr. David Rhys Huggins of Washington State University. Onew of the project's many goals is to test the potential of direct seed, no till farming to return carbon to the top soil. This carbon sequestration could play an important role in the fight against global climate change, as agriculture accounts for about 7% of the carbon released into the atmosphere.

Modern methods of farming have reduced the levels of CO2 in the soil by 30%, Huggins said. He said the situation is even worse on the Palouse because tilling the fields adds to wind and water erosion. The Palouse is the second most erosive area in the country.

No till farming increases carbon in the ground because micro-organisms feed on the residue left in the ground after harvesting. This prevents the carbon from being released into the air as CO2.

Huggins has been working at the farm since 1999, and expects to have hard data on the effects
of no till farming on top soil carbon levels next year. He said only about 10% of the farmers on the Palouse have adopted the method because of the expense of the equipment and the risk required to change farming methods.

Huggins hopes the project will double the levels of carbon in the soil over a ten year period.

Information about other terrestrial carbon sequestration projects can be found at a Department of Energy website: http://cdiac2.esd.ornl.gov/terrestrial.html