By Kristin Withrow, CSDA Communications Specialist
In late August 2023, a historic weather pattern threatened southern California. First feared it would strike with hurricane force winds, it was the catalyst of a declared state of emergency by California Governor Gavin Newsom and California’s first-ever tropical storm warning. When Tropical Storm Hilary descended upon southern California it left a trail of debris in its wake. As residents braced for what was feared to be catastrophic and life-threatening flooding, the Coachella Valley Water District’s (CVWD) stormwater protection plan emerged as a stalwart hero, minimizing damage, and safeguarding the region’s developed areas.
The Coachella Valley is a stunning desert oasis surrounded by towering mountains that has always been susceptible to flash floods during heavy rain events. Yet, the arrival of Tropical Storm Hilary pushed the region’s resilience to the limit. What came next showcased the pivotal role played by CVWD’s stormwater protection infrastructure.
A Backbone of Resilience
One key feature of the CVWD’s Stormwater Master Plan is a 50-mile stormwater channel that snakes its way from the outskirts of Palm Springs to the Salton Sea. Alongside it, approximately eighteen tributary channels capture the deluge of water pouring down from the mountains and canyons encircling the Coachella Valley. This network, as @Lorraine Garcia, CVWD Communication Manager/PIO explains, “is the big backbone of the stormwater protection system, capturing flows and diverting them away from homes and businesses.”
When Tropical Storm Hilary hit, these channels went into overdrive. The storm dumped rainfall in the San Bernardino National Forest at an unprecedented rate, causing a deluge that was as severe as a 1,000-year storm. This terminology means statistically speaking, it has a 1 in 1,000 chance of occurring in a given year; in probability, it has a 0.1% chance of happening in a given year. Debris, rocks, and mud flowed downstream, wreaking havoc on bridges and city streets. However, CVWD’s stormwater protection channels managed this onslaught as well as expected; effectively minimizing damage to homes and businesses protected by the Master Plan infrastructure as it redirected the raging waters toward the Salton Sea.
A Century of Preparedness
Founded in 1918, CVWD has been a stalwart guardian of the Coachella Valley’s water resources for over a century. The district’s extensive service area spans 1,000 square miles and includes over 113,000 metered connections. Apart from stormwater protection, CVWD is responsible for delivering domestic and irrigation water, wastewater collection and recycling, groundwater replenishment, and water conservation efforts.
To prepare for Tropical Storm Hilary, CVWD ensured they had ample staff on standby and the necessary mobile and fixed generators in place to keep critical systems running, even in the event of a power outage. This preparation was crucial, considering the district’s role as a provider of domestic water and sewer services, where system downtime is a critical event. In addition, the district’s public outreach efforts focused on informing the community of the coming risks and coordinating efforts with agency partners in the region.
Protecting the Vulnerable
Despite their remarkable efforts, not all areas of the Coachella Valley are shielded by CVWD’s stormwater protection infrastructure. Some sections remain within Federal Emergency Management Agency (FEMA) marked flood zones. Additionally, roads, cities, and interstates are outside the district’s jurisdiction. Cooperation and coordination with other government entities are vital in these cases.
Certain areas within CVWD’s service area were developed in FEMA flood zones, placing residents in vulnerable situations. CVWD conducts regular public outreach campaigns to inform these communities, empowering them to take measures to protect themselves in the face of such natural disasters.
The Aftermath
The impact of Tropical Storm Hilary remains palpable in the Coachella Valley. Parts of the district’s infrastructure, hardest hit by the storm, are still undergoing repairs. A subsequent storm exacerbated the situation by damaging the canal system responsible for delivering Colorado River water for irrigation, affecting agricultural areas, golf courses, and groundwater replenishment efforts.
As Garcia noted, “We’re not an area built for dams and capturing fast-flowing, floodwater. It’s more about protecting everybody who are in those flood zones.”
Despite the challenges, the Coachella Valley Water District’s dedication to safeguarding the region’s residents and businesses shines through.
In total, the district estimates the damage from the storm to be approximately $3.9 million. On a countywide scale, the County of Riverside reported a staggering damage assessment of $126 million as of August 24, 2023.
As local Reporter Jason Allen from KCAL News aptly observed in the aftermath, “It’s not very often a tropical storm hits the desert.” When it does, the Coachella Valley Water District’s stormwater protection system proves its mettle, providing a beacon of hope in the face of nature’s fury. With continued support and funding, this vital infrastructure will remain steadfast in its mission to safeguard the Coachella Valley’s future.
The Future of Storm Protection in the Coachella Valley
The Regional Stormwater Protection Master Plan has identified priority projects to expand the protection and increase efficiency in the system’s ability to guide runoff around the region's developed areas. Some of these projects have begun while others are still in the assessment and planning stages.
- The Thousand Palms Flood Control Project includes levees and channels to collect stormwater flows from Indio Hills and Little San Bernardino Mountains alluvial fans and convey them to existing stormwater channels in Sun City Palm Desert.
- The North Cathedral City Regional Flood Control Project includes future phases for concrete slope protection, embankment improvements, and bridge undercrossing modifications to collect and convey flows from the Morongo Watershed between Interstate 10 and the Union Pacific Railroad to the Whitewater River Stormwater Channel.
- The North Indio Regional Flood Control Project is currently under construction. When complete in summer of 2024, the project will protect homes and land in North Indio from regional flooding and eliminate the need for flood insurance in the area.
- A portion of the flood protection facilities for the Thermal/Mecca areas are also currently under construction with the Coachella Valley Stormwater Improvements and will be complete by 2024.
- Other areas of the flood control master plan will require additional funding.