This is a one-time contract for fish ladder retrofit design, issued through the CTUIR Accord.  The Mill Creek working group identified the Mill Creek fish ladder as a potential fish barrier in need of improvement.  

The ladder was evaluated by the Washington Department of Fish and Wildlife in 2010 at which time they noted several elements which do not conform with the current fish passage standards. The flow at the USGS gage downstream of the diversion was 52 cfs at the time of the inspection. The following is a summary of the project fish passage concerns:
-The water surface differential at the entrance (downstream end) was estimated as 0.25 – 0.5 feet at the time of the inspection, and it is likely less at higher tailrace water surface elevations. NMFS guidelines encourage a possible range of 0.5 – 2.0 feet.
-The water surface differential at the exit (upstream end) was estimated to be 1.3 – 1.4 feet with the slide gate completely open. A head loss of less than 1-feet at the exit is preferred.
-At 5.5-feet wide, 9-feet long, and 6.5-feet deep, the pools were slightly smaller than the typical values of 6 – 8 feet wide by 10-feet long.

The project has the following objectives:
-Provide improved Salmonid passage, including Spring Chinook, Summer Steelhead, and Bull Trout through the vertical slot weir, including improved fish passage hydraulics at the entrance and the exit of the ladder.
-Provide improved passage for Lamprey, including possible modifications to the existing ladder or a new fish passage structure such as a Lamprey Passage Structure (LPS).
- Provide access and design the improvements to facilitate maintenance and debris control within the ladder.
-Evaluate the need for additional passage flow in accordance with Oregon Department of Fish and Wildlife (ODFW) Fish Passage Criteria (OAR 635-412-0035) and NMFS criteria (NMFS Anadromous Salmonid Fish Passage Design) based on the estimated 95th to 5th percentile in-stream flows.
-Evaluate the long-term operations and maintenance (O&M) benefits to making modifications to the existing 30-year old structure compared to replacement with a new structure.
-Compare the installation, operating, and maintenance cost of passive or automated flow control features compared to manual flow control (manual slide gates).