The consolidation of the Old Lowden and Bergevin-Williams (BWOL) pipelines came about as the result of the BWOL diversion consolidation project which is an ongoing BPA project under 2009-026-00.  Back in 2000 the Confederated Tribes of the Umatilla Indian Reservation (CTUIR) and Bonneville Power Administration (BPA) contracted with Montgomery, Watson & Harza (MWH) to inventory and assess the major barriers to fish passage on the mainstems and major tributaries in the Walla Walla Basin.  MWH followed up with a design effort intended to replace gravel push up dams with a modern diversion that was intended to consolidate four major irrigation ditch diversions located between river mile (RM) 29.2 and RM 31.5 on the Walla Walla River.  Construction of a modern fish friendly irrigation diversion which consolidated the L2 and GC diversions was completed in 2002.  This state of the art diversion has a fish ladder, inflatable diversion dam, and a National Marine Fisheries Service (NMFS) compliant fish screen with an air blast debris removal system.  In 2007, the CTUIR requested and the Walla Walla County Conservation District (WWCCD) agreed to lead a BPA funded effort to upgrade Old Lowden Ditch Corporation (OLDC) and Bergevin-Williams (B-W) diversions.  WDFW and CTUIR biologists working with the WWCCD diversion design team strongly recommended that the Old Lowden and Bergevin-Williams diversions be consolidated with the modern L2 / GC diversion.  

Also in 2007, the OLDC requested that WWCCD work on a WA Department of Ecology (ECY) funded effort to convert their open ditch conveyance system to a pipeline and transfer the saved water to the Trust program.  When WWCCD presented the consolidation concept that was recommended by the diversion design study, the OLDC irrigators were very receptive and invited B-W irrigators to enter into the discussion.  The result of this dialogue was unanimous consensus on a plan that would consolidate the OLDC and B-W ditches into one piped conveyance system and consolidate their diversions with the existing L2 / GC diversion. The proposed pipeline will save approximately 4.5 cfs which is being lost to seepage and evaporation.  All of the saved water will be transferred from thirty individual water rights to the Trust program for perpetuity. The final pipeline design will be completed by the end of August, 2010.  A preliminary cost estimate for the project is $2.145 million.  The consolidated pipeline will consist of approximately 9.2 miles of mainline and lateral pipeline, 30 on-farm irrigation pump stations, 17 on-farm flood irrigation turn outs and 49 meters.  The irrigators will be responsible for operation and maintenance of the pipeline, pump stations, meters, etc.

There has been some concern during the permitting process about dewatering by bringing the lower diversion up to L2 / GC.  As mitigation for this concern, a shallow aquifer recharge project is proposed in this SOW.  The recharge project is intended to increase the quantity of water entering the groundwater and contributing to the base flows of the Walla Walla River to help offset the effects of moving the Old Lowden points of diversion upstream.