Grayson Multi-benefit Flood Risk Reduction Project

Update on 2/4/2022: Project Lead, Short Project Description, Project Cost, and Project Status

Project Lead: Stanislaus County

Potential Project Partners:
No partners identified at this time.

Short Project Description:
The Grayson Multi-benefit Flood Risk Reduction Project is designed to reduce flood hazards in the community of Grayson that are associated with flood flows escaping into the San Joaquin River channel at the entrance to Laird Slough, the primary channel for conveying flows in this reach. In addition to reducing flood risk in Grayson, the project will provide habitat enhancement and public recreation benefits, and help to provide transportation and infrastructure benefits by reducing flooding of Grayson Road, a major east-west corridor across the San Joaquin River. Based on early modeling for the Basin wide Feasibility Study, it appears that the Grayson Road Bridge constitutes a significant local impediment to flood flows on the San Joaquin River. This project would wholly or partially address that issue. This project will provide flood risk management, ecosystem, recreation, transportation, and groundwater recharge benefits.

Long Project Description:
The community of Grayson, CA (population ~1000) is partially included in a mapped 100-year regulatory floodplain according to the Federal Emergency Management Agency (FEMA).  This project will enhance flood conveyance in the San Joaquin River channel under the Grayson Road Bridge, thereby reducing flood stage and attendant flood risk in the community. Stage reduction is anticipated to reduce the frequency and depth to which Grayson Road is inundated during flood events, providing improved access and reducing infrastructure maintenance needs. Enhanced conveyance will be achieved by grading and vegetation management that avoids impacts to wetlands and sensitive species and potentially enhances habitats and ecological functions. Additionally, community access and recreational opportunities will be enhanced, potentially through inclusion of trail features accessible from Grayson and perhaps even extended to Laird Park. Additionally, acquisition of the parcel to the north (Stokman) for multiple purposes, under a separate project proposal, may allow further extension of public access features from this project area to the north.

Unique Project Characteristics:

Based on early modeling for the Basinwide Feasibility Study, it appears that the Grayson Road Bridge constitutes a significant local impediment to flood flows on the San Joaquin River. This project would wholly or partially address that issue.

Project Status	In-progress
Project Cost	$22,000,000
Project Timeframe	1 - 5 years
Cost-sharing	No opportunities identified to date.
Multi-benefit Project	Yes
Types of benefits	Flood risk management, ecosystem, recreation, transportation, groundwater recharge
Source of Project	Mid SJR RFMP Team

Background Information:
None provided