Washington's designation as "The Evergreen State" really only applies to half of the state. The Cascade Mountain Range effectively drains most of the moisture from the atmosphere onto the west side of the mountains leaving the east side with plenty of sunshine, but very little rainfall.

In Washington, irrigation is necessary for the profitable production of most crops east of the Cascade Mountains. Supplemental irrigation is also important in some parts of Western Washington during the hot summer months of June, July, and August. The primary water sources for Eastern Washington are the Columbia, Yakima, and Snake River watersheds. All three of these rivers converge in the Tri-Cities area and flow out to the ocean in the Columbia River. Irrigation is responsible for the large majority of consumptive use of water from these rivers. Water shortages are causing significant concern for the spawning and lifecycles of certain salmon species in these rivers and their tributaries.

Efficient and effective irrigation water management cannot only improve the profitability of agricultural producers, but can result in a decreased need of water and therefore greater in-stream flows for aquatic habitat. Better designed irrigation systems, and more informed and vigilant irrigators can help to accomplish both of these positive outcomes. ~ Washington State University Extension