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Mountain Lake Overflow Pipeline Repair

WHAT

The Presidio Trust will replace the Mountain Lake Overflow Pipeline, an 18-inch metal pipe that is severely corroded and no longer functions, with a new overflow structure. The new structure will allow the Trust to control and maintain the water level in Mountain Lake to protect the lake’s ecosystem, Mountain Lake Park, and Park Presidio Boulevard/Highway 1. The project also includes repair of the overflow pipeline downstream from Mountain Lake.

To access the pipelines for repair, the Trust will clear some vegetation along Mountain Lake and in the Lobos Creek Valley. This work will take place in December 2020 (outside of bird nesting season) and will be replanted with native vegetation in the fall of 2021. Protective measures were developed to avoid and minimize impacts on the San Francisco lessingia, a federally listed endangered plant species that grows in Lobos Creek Valley.

View the map of the work area >>

WHY

The new overflow structure will allow the Trust to control and stabilize the lake water level to protect the aquatic ecosystem, Mountain Lake Park, and Park Presidio Boulevard/Highway 1. Repairs to the downstream overflow pipeline will fix issues with cracked pipes, root intrusion, and soil settlement.

WHEN

December – January 2020
Vegetation clearing at Mountain Lake and in Lobos Creek Valley.

Spring – Fall 2021
Construction to repair the overflow pipeline.

Fall 2021
Native vegetation replanted along Mountain Lake and Lobos Creek Valley.

Questions

Please email us at presidio@presidiotrust.gov.