Greetings!
This edition of the Gallinas Watershed Program newsletter focuses on the geomorphic dredge and Santa Venetia drainage studies. Both studies are slated for completion later this summer, and we anticipate holding a community meeting in the fall to communicate the results. Stay tuned!
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Geomorphic Dredge Assessment of Gallinas Creek
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County Service Area (CSA) #6 has dredged Gallinas Creek four times from 1966 - 1994 to provide navigational access but has not had the funds to pursue a dredge since then.
The purpose of this geomorphic assessment is to establish a more sustainable dredge design to determine a "channel shape that would be expected to form in equilibrium and thus maintain its width and depth with the available natural tidal flushing flows." Preliminary results show some areas where dredging may not be needed and a more triangular cut, with a much narrower bottom, throughout the rest of the dredge extent. The geomorphic dredge would follow the natural thalweg; thus, in many areas the dredge would not be as near to docks as some residents want.
The final report, expected later this summer, will include anticipated dredge volumes, preliminary cost estimates, and potential permitting issues.
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Santa Venetia Drainage Study
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Aging infrastructure, costs of maintaining the existing stormwater system, land subsidence, and sea level rise are key flood protection challenges.
This study utilized GIS data of the existing stormwater infrastructure (including catch basins, pipes, interceptor drains, and pump stations) to develop a stormwater management model (SWMM), which was used to analyze the existing system and is now being used to identify deficiencies and alternatives for maintaining or improving the existing level of flood protection.
Potential solutions could include consolidating pump stations, eliminating the need for portable pumps, and adapting facilities to be resilient to sea level rise. The study is scheduled for completion by the end of summer.
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The Gallinas Creek Flood Protection and Watershed Program is a project of the County of Marin Department of Public Works. Link
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