Novato Creek Bypass Study Project

The purpose of the Novato Creek Bypass Study is to identify opportunities along Novato and lower Warner creeks and through the bypass drainage system for new flow gates, perimeter barriers, pump stations, and increased stormwater detention that would reduce flood risk in downtown Novato and Nave Gardens.

This study builds on the Novato Watershed Study, City of Novato storm drain model, and Countywide LiDAR surface data to better analyze  Novato Creek and the flood bypass system from Arroyo Avichi near South Novato Blvd through Baccaglio Basin, Scottsdale Marsh, and Lynwood Basin.

Mapping and inspections of storm drains, drainage ditches and other facilities in Nave Gardens was completed in 2021. A draft scope for a hydraulic study focusing on the bypass system around this area was prepared for Advisory Board consideration.  Water level gauges were installed in fall 2022, with the rain events of winter 2022/2023 providing good data for the model development.

Project Goals

1. In addition to considering alternatives to sediment removal every four years, evaluate alternative footprints and triggers for sediment removal.
2. Evaluate potential project alternative benefits for smaller flood events (e.g. 10-year event) than the 50-year.
3. Compare project alternatives' benefits and costs, project ranking, and review criteria with advisory board.
4. Comprehensively evaluate the trade-offs between projects that benefit Nave Gardens/South Novato Blvd and their impacts elsewhere.
5. Identify how to fund projects (grants and/or if loan is feasible).
6. Review with City any  potential storm drain improvements that may be more effective in conjunction with potential Zone 1 projects and any opportunities for flow gates in City’s road right of way.

Timeline

The study is anticipated to be completed in late spring 2024.

Status:  The existing conditions model is being completed; an update was provided to the Advisory Board in October 2023.

Funding

The estimated total cost for this study was initially $250,000. In December 2021 the Flood Zone 1 Advisory Board recommended a professional services budget adjustment that increased total study funding up to $300,000.

Zone

Zone 1: Novato

• City of Novato
• Old Town Novato Flood Group
• County of Marin Flood Zone 1