Project Description 

Nicasio Reservoir was created by the construction of Seeger Dam, an earthen filled dam on Nicasio Creek in 1960. The reservoir's current storage capacity is 22,340 acre-feet. This project would increase the capacity at Nicasio Reservoir by 3,000 acre-feet through modifications to the reservoir's spillway. Modifying Nicasio Reservoir’s spillway is one of the near-term storage enlargement projects identified in the District's Water Supply Roadmap. The spillway at Nicasio Reservoir stands alone in terms of flexibility, as the original dam was designed to allow a spillway raise. 

Benefits

The project is a relatively quick and cost-effective way to achieve additional water storage capacity as compared to other, longer-term water supply alternatives within the District’s Roadmap. The additional water supply yielded through this project would help increase the District's water supply resiliency during future droughts. 

Estimated Schedule and Status

Marin Water is currently evaluating three spillway modification approaches in collaboration with regulatory agencies. Once the perfered alterantive is selected a complete engineering design will be completed for the spillway modification alternative for Seeger Dam.

Planning: Summer 2024

Design: Summer 2024 - Spring 2026

Construction: Spring 2026 - Fall 2027

Funding Sources