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
Columbia Institute for Water Policy
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: 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.  It is believed that 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 under Washington laws.  This type of well construction is never allowed in other parts of the state, including, for example, the Yakima basin.  
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, including both 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.)
In 1997, the Department of Ecology attempted to require Odessa irrigators to case their wells, bringing them into compliance with state laws.  The agency issued a press release announcing it would work with Odessa irrigators to case their wells.  Local  backlash was intense, politicians stepped in, and the proposal was dropped. (see article, below)
Despite assurances in the article that Odessa Subarea problems were resolved,  depletion of groundwater has continued.
Overuse & destruction of common pool natural resources is a problem described by Garret Hardin in the classic essay “Tragedy of the Commons.”  While it is the responsibility of the state to regulate to preserve water resources, Washington has done exactly the opposite:  commissioning studies and adopting rules that encourage the depletion of groundwater.  The environmental, economic and ethical consequences of this “race to the bottom” are profound, particularly given that currently favored solutions involve overuse of water resources elsewhere in the Columbia Basin.
Ground water accord reached
The Odessa Record, Mar 27, 1997
    There is apparent agreement among well owners, well drillers, irrigators and the Washington State Department of Ecology that ground water management issues can be resolved to everyone's satisfaction.
    About 100 irrigators, growers and concerned citizens, several from Odessa, met with Ecology representatives Bruce Howard and Dan Weis in Moses Lake on Monday to the dwindling upper aquifer in the Odessa Ground Water Management Subarea, a designation which applies to about 1,100 square miles in Grant, Adams, Lincoln and Franklin counties.
    Ecology had proposed enforcing regulations prohibiting well owners from deepening or repair of irrigation wells without casing and sealing them, a costly process.
    After testimony by well and pump specialist Mel Updegrave, it was agreed the problem could be resolved in other ways than casing wells. Casing will not be required when pumps must be pulled for repair.
    "There was a confrontational attitude as the meeting began, but as it concluded there was a general feeling that well owners and drillers can work with Ecology to solve their individual problems," said Lincoln County Commissioner Bill Graedel, who presented testimony.
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.)