COMMITTEE AGENDA MEMORANDUM
Capital Improvement Program Committee
Government Code ? 84308 Applies: Yes ? No ?
(If "YES" Complete Attachment A - Gov. Code ? 84308)
SUBJECT: title
Receive Moffett Fish Ladder Improvement Project Update.
End
RECOMMENDATION: Recommendation
Receive information on the feasibility analysis and preliminary Staff-Recommended Alternative for the Moffett Fish Ladder Improvement Project.
Body
SUMMARY:
The Moffett fish ladder is a fish passage facility located adjacent to a drop structure on Stevens Creek approximately three miles upstream from the San Francisco Bay, in the City of Mountain View. The goal of the Moffett Fish Ladder Improvement Project (Project) is to improve steelhead passage through the facility. The Project is included in Valley Water's Capital Improvement Program (referred to as Safe Clean Water D4.3 Fish Passage Improvements [Moffett]) and funded through construction.
The Moffett drop structure was originally constructed in the 1960s as a grade control where the streambed drops six feet in elevation over a distance of ten feet. A Denil-style fish ladder was constructed in 1985 by cutting into the concrete drop structure. The fish ladder slope creates high velocity flows which fail to meet all adult and juvenile salmonid passage and attractant flow criteria. In addition, the placement and design of the ladder traps debris within the ladder and encourages sediment deposition at the ladder's upstream exit that restricts fish access to the ladder. These issues are common with Denil fishways, and most experts now favor different approaches to fish passage that take into account the needs of multiple species and life stages.
The Project was identified as one of four priority barriers to fish passage on Stevens Creek by the Fisheries Aquatic Habitat Collaborative Effort (FAHCE) Draft Settlement Agreement. To identify the recommended approach for improving fish passage at the Moffett drop structure, Valley Wat...
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