Contract Description:
The primary component of this contract, is the construction of an irrigation diversion dam on the N.F. Salmon Creek, which will on an average water year provide an additional 3,400 ac-ft. to be stored in Salmon Lake. Work has been rescheduled from contract # 73255 and 73548 Release 14 to this CR.
An agreement with the Okanogan Irrigation District, will dedicate 1,800 ac-ft. of the stored water to in-stream flow for adult and juvenile access in the lower reach of Salmon Creek. This 1,800 ac-ft. will provide 1/2 of the volume necessary to provide perennial flow in lower Salmon Creek.
This project will financially and technically supporting the development of the aforementioned irrigation diversion dam which will result in an increase of 3,400 ac-ft in stored water of which 1,800 ac-ft of the increased stored water will be dedicated to instream flow.
CTCR Contract Manager, CTCR's sponsor, and CTCR's design consultants will all cooperate, coordinate, collaborate, and maintain effective communication with BPA PM/COR, EC Lead, RRT Lead, and Hydraulic Engineer during the entire length of this contract with regards to project design. CTCR and its subcontractors will address BPA comments and concerns, and the two entities will arrive at a mutual beneficial consensus. CTCR contract manager will upload all the subcontracts being executed under this contract.
BACKGROUND/HISTORY OF SALMON CREEK:
The objective of the CTCR is to return perennial flow to Salmon Creek. At a minimum, 3,600 ac-ft is required to meet adequate conditions for the life history for summer steelhead.
Since 1910, water from Salmon Creek has been stored in Conconully Reservoir, which is delivered to agricultural fields within the Okanogan Irrigation District, via ~ 12 miles of Salmon Creek. In addition, the North Fork of Salmon Creek is diverted into Salmon Lake, an off-channel storage reservoir, via a feeder canal. Water is then released from Salmon Lake to augment storage of Conconully Reservoir. Both reservoirs are near the town of Conconully, about 17 miles northwest of Okanogan. Two pumping plants supplement the water supply during water-short years. Shell Rock Pump Station lifts water from the Okanogan River, and Duck Lake Pumping Plant withdraws water from Duck Lake.
Salmon Creek, a tributary to the Okanogan River, is considered to be one of the most significant opportunities to restore summer steelhead in the Okanogan Basin. This project reconnects the Okanogan River with approximately 11 miles of habitat conducive for spawning and rearing of summer steelhead. During controlled water releases in 2003, approximately 25 cfs was required for fish migration downstream of the diversion dam. During 2008 a "low-flow" channel was constructed downstream of the diversion dam which provided suitable fish passage conditions at approximately 10 cfs. The low flow channel extended the duration of water available through a 12-year water lease program. During 2011, uncontrolled spill exceeded 500 cfs resulting in an undistinguishable low flow channel. The low flow channel was re-established after the irrigation season of 2012. This included re-shaping the outlet of Salmon Creek as well as fortifying the stream bank in two reaches, one of which where a structure was in jeopardy of falling into the channel.
In addition land purchases (+200 acres) have occurred within the lowermost 15 miles of Salmon Creek, as well as activating high flow channels, reestablishing spring-fed alcoves, and abating sediment delivery from incised stream banks.
In the future, efforts will be directed at securing the remaining 1,800 ac-ft. to reestablish perennial flow in Salmon Creek. Acquiring an additional 1,800 ac-ft. may come from a number of techniques including increased irrigation efficiencies, long-term water leases, or development of alternative water sources. However, at this time it is uncertain as to the source of funding to secure this additional water.