Existing Conditions - The Marraci/WDFW Irrigation Diversion is located in the Beaver Creek drainage of the Methow Valley Subbasin.  At low flows, the Marracci/WDFW Diversion structure is a barrier to fish passage.  The project objective is to replace this temporary structure with a permanent structure incorporating engineered fish passage.  In addition, the project will pipe a currently un-lined irrigation cana to improve efficiency.

Proposed Improvements - The proposed Marracci project is to replace a diversion structure that is constructed annually from rocks, logs and plastic with a rock v-weir incorporating engineered fish passage.  This structure will be integrated with a redesigned headworks and a ore efficient delivery system for the water that is diverted int he delivery canal to private lands and the WDFW Methow Wildlife Refuge.  The project intends to pipe this canal which could result in a return to the stream of 1.0 to 1.5 cfs of flow.

Site Restoration - Vegetation Removal and Restoration - Some disturbance of vegetation will occur near the bypass channel and the canal but will be limited tho those areas immediately adjacent to the construction areas.

Use of BPA Habitat Improvement Program Biological Opinion and the Hydraulic Permit Application may require a site revegetation plan and potentially monitoring beyond this contract period.  Additional funding may be required for FY 067, 07 and 08.

Personnel - The Okanogan Conservation District will provide a project manager who will develop contract scopes of work for BPA, order necessary supplies, review project designs provided by Reclamation, acquire permits and oversee subcontractor selection and provide construction oversight.

Field Technical staff will assist as needed with construction activities and site rehabilitation activities.

Subcontracts- The landowner will be responsible for contracting for construction work with the assistance of the Conservation District.

-Marrachi Diversion and Piping Project Description-

The Marrachi/WDFW Irrigation Diversion is located in the Beaver Creek drainage of the Methow Valley Subbasin.  Beaver Creek is listed in the Washington Conservation Commission's Limiting Factors Report and the USFS Middle Methow Watershed Assessment as potential habitat for listed Upper Columbia steelhead, Upper Columbia spring Chinook, and bull trout.  These species presently occupy less than 10% of the potential habitat in Beaver Creek because of passage barriers created by culverts and impassable irrigation diversion dams.  At low flows, the Marrachi/WDFW Diversion structure is a barrier to these species.  The project objective is to replace this temporary structure with a permanent structure incorporating engineered fish passage and to improve late season flows in Beaver Creek by piping the delivery system.  

The Methow Subbasin Plan prepared for the Northwest Power and Conservation Council considers these listed fish species as focal species for conservation priority and identifies limiting factors for the recovery of these species.  These factors include construction of artificial barriers to fish passage such as push up dams, diversions, and ill-functioning fish screens and culverts.  In addition water quantity is a crucial factor affecting overall habitat quality in the Methow Subbasin.  Numerous streams and creeks throughout the Methow watershed are prone to naturally occurring seasonal low flows and occasional dewatering.  Those natural low flows and instances of dewatering have been compounded in some instances by irrigation withdrawals and by agricultural water use inefficiencies in some Methow tributaries such as Beaver Creek.

Beaver Creek is major tributary of the Methow Subbasin that flows into the Methow River at river mile 35.2 that is 5 miles downstream from the town of Twisp.  The Beaver Creek system drains approximately 71,400 acres in Okanogan County and includes the tributaries:  Lightning Creek, Blue Buck Creek, Frazer Creek., and the South and Middle Forks of Beaver Creek.  Beaver Creek. and the tributaries are inhabited by resident rainbow trout, introduced Eastern brook trout, and Upper Columbia steelhead and an isolated bull trout population in the headwater tributaries in addition to brook/bull trout hybrids.  In the lower reaches Beaver Creek. goes dry in low water years in the fall because the subwatershed is an adjudicated drainage where water uses are provided in excess of available water during part of the irrigation season.  The exception to this is in the lowest 0.3 miles of the drainage where surface flow is maintained via irrigation return flows.  Beaver Creek is listed on the Washington State Dept. of Ecology's 303(d) list for flow because during dry years the stream is dewatered below the lowest diversion.

The proposed Marrachi project is to replace a diversion structure that is constructed annually from rocks, logs and plastic that is a low flow barrier to fish passage with a rock v-weir incorporating engineered fish passage.  This structure will be integrated with a redesigned headworks and a more efficient delivery system for the water that is diverted in the delivery canal to private lands and the WDFW Methow Wildlife Refuge.  The delivery canal is an unlined ditch constructed in sandy soils where seepage losses could be 50 to 70%.  The project intends to pipe this canal which could result in a return to the stream of 1.0 to 1.5 .c.f.s. of flow.