SALTON SEA MANAGEMENT PROGRAM: Tropical Storm Hilary Leaves Minimal Impacts on Salton Sea Restoration Projects

From the Salton Sea Management Program:

As communities continue to recover from the impacts of Tropical Storm Hilary, active restoration projects around the Salton Sea report minimal construction damage in the wake of the storm.

Species Conservation Habitat Project Accommodates Flood Flows

The Species Conservation Habitat Project (SCH), located at the southern end of the Salton Sea, saw an increase in flows from the New River as a result of the storm. The increase amounted to twice the typical inflow during the active storm period.

Water retained at New River Diversion Structure at the Salton Sea
The New River Diversion Structure is a major component of the overall SCH Project. It is also a flood control structure that will allow for water to go through without compromising the integrity of the project.

The New River Diversion Structure was able to adequately capture and retain water as planned. However, the flood gates were opened out of an abundance of caution even though rain levels and New River inflows were below the forecasted levels.

New River Diversion structure with flood gates open to allow water to flow into the Sea
Flood gates at the New River Diversion Structure were opened to allow water to continue its way into the Sea.

After opening the flood gates, water continued its way and streamed through the New River until reaching the Salton Sea. The SCH was designed and built to undertake a 100-year flood event protecting the overall integrity of the project and helping protect adjacent land properties from flooding.

Erosion at Flood buffer zone
Water overtopped the interception ditch going into the flood buffer zone, causing some sediment to be deposited or removed from the berm.

With the substantial amount of water that came in, the interception ditch, another component of the SCH project, did overtop into the flood buffer zone. The interception ditch is designed to do that, by letting the water flow by gravity into the flood buffer zone. As a result of the overtopping, some erosion did occur in the berm situated between the interception ditch and the flood buffer zone.

Vegetation Enhancement Projects Report No Significant Damage

Ephemeral stream moved grass bales
Some grass bales were moved around the sites in areas with high water flows where water collected formed streams.

Although Tropical Storm Hilary brought in a significant amount of water into the Sea’s shoreline, the Vegetation Enhancement Project sites report no significant damage within the project areas. Storm runoff eroded soil and created waterways known as ephemeral streams. Now that these streams have emerged, the SSMP team can plan to capture, divert, and spread stormwater in a more controlled manner in the future. In addition, these storm events allow the SSMP to better determine and identify the best areas to place the grass bales. Displaced bales will not be returned to their original placement.

Aerial view of Vegetation enhancement site showing how water moved through the site
This aerial view at Clubhouse site near Salton City shows how storm water spread through the site. Existing and new vegetation will benefit from the recent rains.

In fact, the substantial amount of water that moved through the project areas is significantly beneficial for natural plant recruitment and supports existing younger plants across all vegetation enhancement sites.

Events like Tropical Storm Hilary gives the SSMP an opportunity to see if projects are operating as designed and how to adaptively manage each project’s maintenance and reinforce any specific areas.

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