Cascading Wells
![“The department [of Ecology] shall require wells to be so constructed and maintained as to prevent the waste of public ground waters through leaky casings, pipes, fittings, valves, or pumps -- either above or below the land surface . . .”
RCW 90.44.110, Waste of water prohibited —Exceptions
“Water wells may not interconnect aquifers.”
WAC 173-160-181
"Improperly constructed wells allow water from the upper aquifer to drain down to the lower aquifer. That means that people with shallow wells are losing water to the lower aquifer and some of these wells actually run dry."
Washington Dept. of Ecology news release, 1997](Cascading%20Wells_files/shapeimage_2.png)
CASCADING WELLS
The third reason that Odessa Aquifers are declining is because of poorly constructed wells in the region. Indeed, the problem of depleted groundwater in Odessa is partly caused by Odessa irrigators themselves.
Odessa Subarea wells tend to be deep and penetrate through multiple layers of basalt. When a well pierces through multiple layers of basalt and is not properly sealed, water cascades down the hole to lower levels. “Cascading wells” enable a water user to pull water from multiple aquifer levels, but they also drain upper aquifers into lower aquifers.
Illustration showing how wells penetrate through multiple layers of basalt, allowing water to cascade down to lower levels, draining upper aquifers. From Cline, D.R., “Ground-Water Levels & Pumpage in East-Central Washington”, Water Supply Bulletin No. 55 (USGS & Dep’t of Ecology, 1984)
Hundreds, possibly thousands, of Odessa wells are “uncased,” meaning that they are open to and drawing from several different aquifer systems. The deep wells of the Odessa Subarea are causing the aquifer system to decline.
Uncased wells that allow water to cascade down hole are illegal. This type of well construction is never allowed in other parts of the state, including, for example, the Yakima basin. The Department of Ecology has made feeble attempts to require Odessa irrigators to bring their wells into compliance with state law, but the agency has never enforced the anti-waste statutes.
Well log for a well located near odessa. The driller descriptions of geologic strata penetrated by this well indicate that it is open to multiple strata that may contain groundwater. Based on professional judgment, the well appears to penetrate through the Wanapum and into Grande Ronde Basalt aquifers. The well has a casing and surface seal across the top 60 feet and is open below to a final depth of 920 feet bgs. (Source: WRIA 43 Watershed Assessment.)
Diagrammatic section through Odessa test-observation well 20/33-16E1-E6, showing piezometer pipes and the aquifer zones they measure (modified from Walters, Clinc, and Luzier, 1972.)
