Little Creek is located in the southeast portion of the Grande Ronde Valley and is a tributary to Catherine Creek with the confluence downstream of Union, Oregon.  Associated Subwatershed: CC2C; Associated Opportunity: CC2C - CC 35.8 - 36.0: Little Creek.  Little Creek originates on the west side of the Wallowa Mountains and flows through a valley setting with two separate and distinct landforms that influence the channel. The upstream reaches flow through coniferous forest and rangeland into a confined canyon and is relatively high gradient ranging from 4-10%.  As Little Creek exits this canyon and enters the Grande Ronde Valley floor, the gradient is reduced to less than 2% and the channel flows through urban and rural agricultural areas. There are 6 irrigation diversion structures on Little Creek within the valley reach. With the exception of the most downstream White Diversion (LC1), all of the structures are currently unscreened and have been identified as potential fish migration barriers during specific times of the year.  Water rights on Little Creek are considered over appropriated and instream flow during summer months can become very low. This project is focused on restoring fish passage for adult and juvenile salmonids past the LC5 and LC6 diversions, but additionally could augment instream flows through increasing diversion efficiency and properly metering diversion volumes.

From 2010 to 2013 the U. S. Bureau of Reclamation (USBR) began collecting data on the Israel Ames (LC6) and the Weaver Lane (LC5) diversion structures which resulted in the production of Alternatives Evaluation Reports (AER) for both sites.  Both ditch associations ultimately agreed to alternatives selected from that AER produced by the USBR in 2011 and voted to proceed with plans for diversion updates and construction of fish passage. In 2020, the Union SWCD coordinated with water users and land owners to develop a proposal for a Technical Assistance grant to complete engineered designs at both sites.  The District received engineering funds and contracted with Anderson Perry and Associates in 2021 to develop fish passage alternatives and design the chosen alternative to final construction package.  The design for this construction contract can be found under 85944.

The project goal for the Little Creek LC5/6 Fish Passage Construction is to improve fish passage around the Weaver and Israel-Ames irrigation diversion dams on Little Creek to allow juvenile and adult spring/summer Chinook salmon (Oncorhynchus tshawytscha) and summer steelhead (Oncorhynchus mykiss) to access high quality habitat in Little Creek while preventing fish from entering the irrigation system. Fish passage criteria for design will be based on allowing passage of bull trout and Pacific lamprey, as those are the most stringent requirements and will allow all other salmonids to pass. The existing diversion structures at both sites will be replaced by laydown stanchions that will allow open flow in the channel during the non-irrigation season. The diversion structures will include installation of rotary drum fish screens manufactured and installed by ODFW. A fish bypass channel will be constructed off the main channel on river left of both diversions. The bypass channels will be constructed with streambed simulation material to mimic natural channel design and maintain appropriate velocities for fish passage.

The outcome of this project will construct new in-stream diversion structures with roughened bypass channels to allow for fish passage and will include fish screens and flow meters on the irrigation ditches.  The projects will improve access to 21.4 kilometers of main stem and tributary habitat for all listed species in the Caterine Creek Drainage.

Objective #1 - Improve conditions for fish passage for juvenile and adult spring/summer Chinook salmon (O. tshawytscha) and summer steelhead (O.mykiss) during periods of migration that achieve Oregon Department of Fish and Wildlife (ODFW) and National Marine Fisheries Service (NMFS) fish passage criteria to the greatest extent possible.

Objective #2 - Eliminate access for fish and the opportunity for stranding in the irrigation system through the installation of fish screens.

Objective #3 - Increase instream flow by improving water use efficiency and decreasing diverted water volumes.

Objective #4 - Restore natural instream hydrology and sediment routing processes during the non-irrigation season.