Groundwater (UIC Wells)

In some places within the County, stormwater is disposed of through dry wells, also called an underground injection control (UIC) well, instead of flowing to a stream or river. UIC wells collect and hold stormwater underground, and slowly drain the water into the soil below and around the well. Depending on the depth of the ground water below the well and the type of soil surrounding the well, the stormwater may drain, or infiltrate, into the aquifer below. Since stormwater picks up contaminants as it runs over the land surface, the stormwater can pollute the ground water once infiltration occurs.

UIC wells can be a very effective means of disposing of stormwater; however, these wells are regulated by the Department of Ecology to ensure they are not adversely affecting the ground water below the wells. The UIC Program administered by the Department of Ecology has two basic requirements:

• Owners must locate and register their UIC wells with the Department of Ecology unless the wells are located on tribal land. (Those wells should be registered with the EPA).
• Make sure that current and future underground sources of ground water are not endangered by pollutants in the stormwater discharge (non-endangerment standard).

The Program also states that UIC wells constructed on or after February 3, 2006 are considered to be new. New wells must be registered, and you must provide the department with information needed to determine if the new UIC wells meet the conditions to be rule-authorized. The registration form must be submitted prior to construction, and the non-endangerment standard must be met.

• Owners of 50 wells or fewer must register their wells by February 3, 2009, and complete their well assessment by February 3, 2011.
• Owners of more than 50 wells must register their wells by February 3, 2011, and complete their well assessment by February 3, 2013.

Asotin County, Asotin and Clarkston are in the process of creating an inventory of all new and existing wells under their ownership, and will begin to register their wells once the inventory process is complete. For more information on the Washington State Department of Ecology Underground Injection Control Well Program, click here.