DESCRIPTION
The current project scope includes pumping water from a new surface diversion adjacent to the confluence of the Wenatchee and Columbia Rivers and delivering the water under pressure to shareholders on the north side of the river. This will be made possible by transferring authority and responsibility of service to PWUA south side users to Regional Water Supply (Regional). That said, due to the scale and cost of this project, the project scope has changed significantly over the past year, but the current plan for the north side pump-back now has concurrence from the PWUA board and Regional Water Supply. The nature of the problem this project addresses is low instream flow in the lower Wenatchee River and fish passage at the current diversion side channel. The protection of instream flow aims to improve the natural geomorphic river processes and addresses the root of problems in the Wenatchee River. Peak water use in the Wenatchee River is during the dry summer months when there is little or no precipitation to help meet water demand. A majority of water withdrawn from the Wenatchee River from April to October each year is withdrawn by irrigation districts. There are 4 major irrigation districts in the Wenatchee River which provide irrigation water most agricultural lands, covering several thousand service acres. Instream flow is a limiting factor in the Wenatchee River and this project will help improve flow conditions, particularly from August through October
The objective of this project is to improve habitat by increasing flows in the Lower Wenatchee by 38.27 cubic-feet per second (CFS). This project intiated and implemented the primary phase of the Pioneer Water Users Association project in the lower 7.0 miles of the Wenatchee River. This project created infrastructure improvements for the Pioneer Water Users Association (PWUA) who operate and maintain the Gunn Ditch, which supplies water for agricultural and residential irrigation to shareholders. The project has several components that will address limiting factors in the Wenatchee and is part of the Upper Columbia Salmon Recovery Board implementation schedule. By initiating this project, other biologically productive restoration activities can also be implemented, including habitat improvements, diversion removal, and possible side channel reconnection.
This project has three key elements: 1) The project will replace the PWUA current conveyance system, a gravity fed open ditch, with a new enclosed pressurized system and 2) change the PWUA point of diversion from the flow limited Wenatchee River to the confluence with the Columbia River and 3) will remove a side channel concrete diversion dam just upstream of Monitor. This project protects 38.27 cfs of the historically diverted water back into the lower 7.0 miles of the Wenatchee River, benefiting habitat for fish, particularly during low flows. The water is permanently protected as an in-stream flow right through Washington States Trust Water Rights Program (TWRP).
