Since spring of 2007, Washington Water Trust has worked cooperatively with the Department of Ecology and Walla Walla County to develop mitigation requirements for certain new well users in the Walla Walla Basin that support water for people and water for streams through a "mitigation exchange."

An amended instream flow rule for the Walla Walla Basin was adopted in Septmber of 2007. Details on the rule can be found here: (http://www.ecy.wa.gov/programs/wr/instream-flows/wallawallabasin.html).  The instream flow rule set flows for Walla Walla basin streams and closed most sources to new appropriation. In addition the rule required all new wells that are drilled in the shallow gravel aquifer within areas zoned 10 acres or denser to mitigate for their impact on stream flows. Washington Water Trust was hired by the Department of Ecology to come up with a streamlined solution for new home builders to obtain this mitigation.  

First WWT worked with Ecology and Walla Walla County to develop a mitigation plan revolving around the purchase of water which was transferred to the State Trust Water Program.  Then in May of 2008, Washington Water Trust launched the Walla Walla Water Exchange.    The exchange holds the retired water rights in trust for the benefit of stream flows. New home builders pay a one time fee to the water exchange (cost of their portion of water acquired to mitigate) and in turn pump water from their well for use outdoors for gardening and watering.  

Beginning in 2011, Washington Water Trust passed on management of the Walla Walla Water Exchange to the Walla Walla Watershed Management Partnership.  More information on the Partnership can be found here:  http://www.wallawallawatershed.org/participate