Coho struggling to jump over the concrete apron at the SF Klaskanine Hatchery

The South Fork Klaskanine Hatchery was built in 1980 for the Clatsop Economic Development Council’s (CEDC) Net Pen program. The program raises spring chinook to supplement the gill net fishery and economic development. As part of the hatchery, a water diversion dam was installed spanning the width of the river. At the time of construction, an attempt was made to provide adequate fish passage for coho, steelhead and searun cutthroat trout. Unfortunately, the attempt feel short of expectations and anadromous fish struggle to pass the structure.

The hatchery currently raises spring chinook to smolt stage before they are then placed in net pens in the Youngs Bay estuary to imprint. As yearlings they are released at the mouth of the Columbia River. The need for fish passage at the diversion dam is targeted at wild fish--not returning, uncaught hatchery fish.

Problem

The current structure passes fish only at a certain flow; if flow is too low or too high passage is limited. The problem is related to two items: 1. Passage over the lower concrete apron requires a jump of approximately 10 feet. The majority of the time fish are not able to completely jump the required distance. If they fail to clear the entire barrier, they slide back down due to the steep angle of the apron. If they are successful in passing the initial apron, the next jump also presents a problem. 2. At the top of the apron, there is a plunge pool of approximately 4’ wide x 8’ long with a 2 ft. high weir. The plunge pool is not large enough for an adult coho, chinook or steelhead to prepare for its jump directly into the next section of ladder. Because the pool is too small, fish move to a larger pool off to the side to rest before trying to clear the weir. The location of this pool creates an awkward angle for the fish to make their leap. In effect, they try to clear the weir at a 45-degree angle, many times hitting the weir or concrete wall and sliding back down the lower concrete apron.

Solution/Technique

Installing an Alaskan Steep Pass (Pass) will provide adequate passage for returning adults and out-migrating juvenile salmonids (please see attached designs). This application was chosen for its effective design in passing adult and juvenile salmonids, its relatively inexpensive construction cost and the short in-water period needed. The Pass has proven efficient for passing adult Chinook, coho and chum at hatcheries in Alaska. It’s proven successful at a 28-degree angle over the distances of 30’. The Pass will be constructed of mild-steel hot dipped in galvanizing to protect it from rusting. CEDC has staffing at the hatchery 7 days per week, year round. Daily maintenance (cleaning out debris, checking for blockages, etc.) of the Pass will be incorporated as part of the daily hatchery duties.

The project is slated to begin Summer 2005 with funding from CEDC and ODFW Fish Passage and Screening Funds. Total estimated cost is $68,540.