Reduce peak flood flows into the river. – LA River Master Plan

Back to: Reduce flood risk and improve resiliency.

Action: Reduce peak flood flows into the river.

In addition to increasing capacity of the river, flood risk can also be improved by reducing the amount of water that enters the LA River at peak flows.

Upstream storage or detention facilities, such as dams, help to store runoff during large storm events and slowly release the water so as not to exceed the downstream channel capacity. Groundwater recharge facilities direct stormwater to spreading grounds, where the water can percolate into the groundwater basins for later use.

County Lead

LA County Public Works / Flood Control District

Potential Partners

Entities with Stormwater Responsibilities (e.g., Caltrans, Metro, industrial facilities)

Geographic Boundaries

LA River Watershed

Potential Funding Sources

Congressionally authorized studies and projects through USACE Civil Works Authority

FEMA Flood Mitigation Assistance (FMA) Grant Program

Click above for other actions that involve the implementation lead or potential partners or that apply to the same geographic boundaries.

Methods

specific, tangible ways to reach the goal

Evaluate regional scale upstream dams and detention basins for opportunities to reduce flood risk downstream.
Increase capacity of existing dams and detention basins through measures such as clearing debris, deepening basins, increasing dam and levee heights, and improving real-time controls.
Related Actions/Methods
Increase capacity of the river in high risk areas to provide flood risk reduction to at least the 1% (100-year) annual chance flood event or to a level recommended by a risk assessment.

Improve flood facility operations and maintenance.

Increase plant species biodiversity, and focus on the use of local California native plants in and around the river corridor.

Sepulveda Basin is an important asset to reduce peak flows on the LA River.

OLIN, 2019.