Watershead, Fall 2010
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Expert Panel Defines Five Options For New Fishway At Freeman Diversion

In a newly-released report, a panel of experts has defined five possible ways to revamp the Vern Freeman Diversion Dam (VFDD – shown above) for successful fish passage. This study was carried out as a condition of a lawsuit settlement between the United Water Conservation District and CalTrout. FSCR, CalTrout and Keep the Sespe Wild Committee have long fought for a solution to fish passage at the Diversion that will allow successful upstream migration of the federally endangered southern steelhead.

The options are: (1) remove the dam completely with direct piping of water from Lake Piru to United's settling ponds; (2) a vertical slot fishway similar to the current fishladder but with much improved entrance conditions; (3) a 4% grade, 82-foot wide rock ramp that would extend 562 feet upstream from the top of the dam; (4) a 6% grade concrete ramp similar to the rock ramp that would extend 367 feet from the dam top; (5) a 26-foot wide "nature-like" fishway that would provide a more natural rock-bottom, vegetated channel around the dam.

The study included cost estimates for each option. These varied from $24 to $28 million for all but the rock ramp which was estimated to cost $46 million. Funding would have to come from rate increases to United's customers unless federal funding or grant money can be obtained.

The panel recommended the vertical slot fishway and the concrete ramp as the most promising options for further studies, but said all options deserve further consideration before a final design is selected.

United has claimed for years that the existing fishladder allows upstream migration of adult steelhead. However, to our knowledge, there is no recorded instance of an adult fish successfully transitioning the ladder. Some have been found dead and at least one was rescued alive from the upper part of the ladder. Smolts (young steelhead) going downstream and do not pass over the dam itself are normally trapped at the Diversion and transported to the Santa Clara estuary, from which they (hopefully) reach the ocean.

The dam removal option was not analyzed by the panel since it was considered beyond their level of expertise. However, the panel stated that "Considering the highly variable hydrologic characteristics of the basin, edge of steelhead ecosystem, fragility of the stock, inherent delays caused by dams, dam removal would have the greatest chance of allowing and promoting restoration of Santa Clara River fish stocks." Although there are many ramifications to dam removal that would require extensive hydraulic and water supply studies, this option needs to remain on the table as a long-term goal.


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