December 21, 2015 - From the December, 2015 issue

LA County Public Works: Preparing for Impacts of El Niño

With extreme rain forecasted this coming winter, after years of record-setting drought, Southern California must prepare to both take advantage of the precipitation and ensure it does not cause harm. Deputy Director of Los Angeles County’s Department of Public Works Gary Hildebrand spoke with MIR about these efforts, noting also that the agency remains prepared, even without El Niño, for large storm events. He highlights stormwater capture, reuse, and infiltration operations, along with considering the LA River’s flood control capabilities.

Gary Hildebrand

“The Flood Control District and the Army Corps of Engineers together have the responsibility to operate and maintain the LA River...[with]projects to restore, rehabilitate, and provide more multi-benefit opportunities along the river.” -Gary Hildebrand

With 30 years of experience at the LA County Department of Public Works, share with our readers what your responsibilities include.

Gary Hildebrand: As a deputy director of Public Works, I manage our Water Resources Core Service Area, one of six core service areas here. Within that service area, I oversee the Los Angeles County Flood Control District: a special district within a majority of the county responsible for providing flood protection to the urban areas, along with capturing storm water for reuse and replenishing our groundwater basins. 

I also manage the five Waterworks Districts operated by Public Works. We’re a local water retailer for five locations in the county, primarily in the Antelope Valley and in the Malibu area. 

I deal with watershed management efforts in the county unincorporated areas, including storm-water quality compliance and drainage issues. 

On people’s minds in Southern California are reports to expect a very significant El Niño. How does that affect your responsibilities and planning?

In the Flood Control District, we operate major flood control infrastructure throughout the metropolitan area of LA County. We have 14 dams in the San Gabriel Mountains. We have about 500 miles of flood-control channels, which serve as a backbone of the drainage network. We also have about 3,000 miles of underground storm drain that feed into that. 

We work with the local cities. They have much of the localized drainage infrastructure that discharges into our system, which ultimately manages the storm flows throughout the county. 

For the Flood Control District, the operation and maintenance of our system is an ongoing effort. We’re always maintaining, repairing, and rehabilitating the system, since we have to go into every winter season with our system fully ready to capture large storm events. 

With El Niño, there’s concern about larger quantities of rain and more storms. But in any particular storm season, you can have very large storm events, and we have to be ready to handle them. 

People talk about the last El Niño in 1997-1998. But it isn’t widely recognized that the 2004-2005 storm season was the second-wettest on record. That was the largest season our flood control system has ever faced. We functioned extremely well during that time.

With the drought for so many years since then, and now the threat of this larger El Niño, what’s the challenge of dealing with the catch basins—particularly with the homeless encampments on the riverbeds and other danger areas for flooding? How does that come to bear on your resources, and priorities?

We have a response plan in place to deal with our operations during storm events, in terms of how we man our facilities and how we go about responding should there be flooding incidents. We fine-tune that each year. 

This year, because of El Niño, there is more heightened concern about the impacts to homeless encampments that are within our flood control network. We are working with the Office of Emergency Management, the County Public Health Department, and homeless advocate agencies to develop more efforts to outreach to the homeless on the dangers of being in our flood control channels—looking at proactive educational efforts and also placing signage along waterways. Also, we’re working with the various organizations to ensure that there are places for the homeless to go, should they have to leave the locations in our flood-control network.

Let’s transition to the LA River, particularly the Flood Control District’s involvement in the vision and ongoing planning there. MIR has run numerous interviews with players in that process. We are eager to hear the county’s perspective on what’s at play along its 51-mile stretch.

The Flood Control District and the US Army Corps of Engineers together have the responsibility to operate and maintain the LA River. The river itself is divided between the two organizations in terms of primary responsibility—the Corps of Engineers has primary responsibility over the portion that was the focus of the LA River Ecosystem Restoration Study. We participated in the study and support the overall restoration efforts. Our Board of Supervisors passed a motion supporting the study and Alternative 20, which was ultimately pursued by the Corps. 

We’ve been working for many years on projects to restore, rehabilitate, and provide more multi-benefit opportunities along the river. Within the reaches of the river where we have primary responsibility, we’ve already completed a number of projects that have provided additional recreational access, additional habitat, and storm-water capture opportunities to the region. 

One element of river revitalization involves removing concrete from the channel, which is there to speed the water out to the ocean. What are your thoughts about the dual goals of flood protection and resiliency, and recreational and city use of that channel?

All of these studies and efforts proceed with the goal of retaining the same level of flood protection for our urban areas, which have evolved over decades on the assumption that we do have a drainage system. As we look at ways to restore, renovate, and rehabilitate the river, it’s always going to be through the lens of providing that same level of flood risk management.

There are many opportunities where we can incorporate additional recreation and modify the concrete and still meet that goal.

In the reports on architect Frank Gehry’s year-long planning process, he said that in reimagining the river, you need to start with hydrology. But he’s an architect. Can you comment on his approach?

The hydrology of the river comes into play in understanding what happens during a storm event, how the water ends up in the river, the magnitude and size of those flows, and how they’re being managed in the river during storms. 

While Frank Gehry is an architect, he does have, as part of his team, engineers who are looking at the hydraulic aspects and understand the current level of flood protection provided by the river. They’re looking at how the future vision and potential changes to the river can be accomplished while still providing the same level of flood risk management to the surrounding communities. 

What advice would you offer Gehry about the hydrology of the river?

As his project unfolds, both our department and the Army Corps of Engineers will be providing input to the team, based on our historical experience managing the river. We’ll comment on how opportunities identified as part of the planning process would impact the management of the river and its ability to provide the current level of flood risk management. 

We’ll provide our knowledge base so that multiple goals can be coequally met without any negative impacts to the public.

The last issue of MIR included an interview with Rob Katherman of the Water Replenishment District board. Share with our readers the nexus between the Water Replenishment District and County Public Works’ responsibilities.

The Water Replenishment District is responsible for managing the Central and West Coast Groundwater Basins. Their role is to ensure that, as part of the basin being properly managed, it is properly replenished with water to be able to serve its water supply function to the region. The groundwater basins are recharged with water through facilities operated by the Flood Control District through Public Works. 

I mentioned earlier that one of our missions at the Flood Control District is storm-water capture for groundwater recharge. Throughout the LA region, we’ve constructed 27 spreading grounds. 

Our flood-control system is designed for multiple purposes. Yes, it’s designed to provide flood protection in large storm events. But in more frequent, ongoing events, it’s operated to capture that storm water and redirect it into our spreading grounds for groundwater recharge. 


Two of our spreading grounds replenish the two groundwater basins managed by the Water Replenishment District. Recycled water is also used to replenish the Central and West groundwater basins, and we’ve been working together with the Water Replenishment District and the Sanitation Districts of Los Angeles County on using recycled wastewater for that replenishment in the Central Basin since the early ‘60s. That was one of the first water-replenishment projects in the region to use recycled wastewater for groundwater recharge. It’s been extremely successful. 

The Water Replenishment District is the agency that actually purchases that water for replenishment in the Central Groundwater Basin, and the County Sanitation District is the producer of the water. They provide that water to the Flood Control District, and we transport it down into our system and use our spreading grounds to replenish the groundwater basins. Those are the mechanics of that process.

Let’s turn to “One Water” efforts to break down silos we’ve created over a century, with respect to California water management. What are the challenges and benefits of collaborative efforts going on for some time, and more recently in the last five or six years as water has come to the forefront of public attention?

The Flood Control District is a regional agency here in the county. We’ve interacted with many water agencies for many years on projects that involve our local water supply and increasing our local sustainability. 

We just talked about our interactions with the Water Replenishment District and the Sanitation Districts on the use of recycled water to increase our local water supply. That’s been a longstanding, successful collaboration with those two agencies. We’ve worked for many years to expand the capability of storm-water capture at our facilities, both at our dams and our spreading grounds. We’ve worked directly with the various water supply agencies in the county that benefit from our storm-water capture efforts to develop concepts for projects that expand our capacity, and also to identify funding for them. We’ve worked very closely with the City of LA Department of Water and Power on collaborative projects that have expanded the capability of our groundwater recharge facilities in the east San Fernando Valley. We’ve worked with water agencies in the San Gabriel Valley—the Main San Gabriel Basin Watermaster and the other local water agencies—on collaboratively planned and funded projects that we have built over the years to expand our capability. 

Going into El Niño this season, we’re often asked: We’ve been in a drought for four years. Now we’re getting a lot of water. What are you all doing to be able to capture that? We’ve had the foresight to realize that it takes some time to develop these projects and get them built. For us, it’s been an ongoing process over the last 20 years to expand the capability of our spreading grounds, expand the capability of our dams, and work with our local water agency partners to develop, fund, and build those projects. Over the last 15 years, we have spent tens of millions of dollars expanding our facilities to be able to capture more water, so that in those wetter years we will have the facilities and infrastructure to capture additional water.

MIR has often covered the Sun Valley Watershed Multi-Benefit Project, but never from your perspective. Could you describe the collaboration behind the project, and how it took a different approach to attacking the problem of water management?

Ratchet back to about 15 years ago, and the east San Fernando Valley was one of the last remaining areas in the county that had pretty severe regional flooding issues. Prior to that time, the Flood Control District’s traditional approach would have been to build a typical storm drain to collect runoff and move it out of the watershed. 

But thoughts were changing about how to manage watersheds at that time. TreePeople and others approached us and asked: Can we manage this flooding in a different way that not only takes care of the issue, but also brings in other multiple benefits to the community, like habitat restoration and recreation?

Working together with TreePeople, the City of Los Angeles, and the community, we developed the Sun Valley Watershed Management Plan, which viewed storm water as a true resource for the community. 

We were very successful with that project. In lieu of a traditional single-purpose storm drain, the Sun Valley Watershed Plan came out with about 15 different projects that all involved capturing and reusing storm water within the watershed. Plans for these larger- and smaller-scale projects provided the needed flood protection in the watershed, and also identified opportunities to increase local water supply and provide additional recreational and habitat amenities. 

Since the Sun Valley Watershed Plan was completed, we’ve completed construction on a number of projects in the watershed, such as Sun Valley Park, the Elmer Avenue Neighborhood Retrofit and the Tuxford Green Project. We’re also well into the planning phases of one of the signature projects of the Sun Valley Watershed: the Rory Shaw Wetlands Park. That involves a 46-acre parcel of land, purchased collectively by the Flood Control District and the City of LA. It’s a former, inert construction debris landfill that will be converted into a regional flood-control facility to capture storm water from the surrounding watershed area, hold that water, use it for groundwater infiltration, provide park amenities to the community, and also include habitat-like wetlands. Note that Sun Valley is one of the most park-poor areas in the City of LA. We expect that project to be completed in 2020.

With the drought and increased attention on the threat of a seismic event that would cut the California aqueduct, there’s been a push to reduce imported water—creating a focus on recharge and reuse of storm water. What collaborative conversations are going on to meet the stretch goals of cutting imported water by 50 percent to the Los Angeles metropolitan area?

As part of reducing the need for imported water, in the Flood Control District, our primary role has been to work with water agencies and increase the ability to capture storm water. 

Right now, storm water and our groundwater basins provide about a third of the local water supply. Depending on where you are in the county, that percentage can be greater or less. Realizing that our imported water supplies are threatened by the drought and also climate change, and with the push to increase local sustainability, we’ve been working more closely with our water agency partners to identify and develop projects that increase local storm-water capture. We’re also working with them to increase the use of other sources of water within our portfolio, such as recycled water. 

As we move forward, all of these projects that come to fruition will allow us to contribute a greater portion to the local water supply through these local sources, and truly become less reliant on imported water.

There’s been much discussion about the river potentially being used in this effort for storage. Is there a portable dam idea, at low tide, that’s feasible for the river and that’s a reliable vehicle for storing water for the system?

We use rubber dams extensively, now, throughout our system to capture and infiltrate water. The San Gabriel River—from its headwaters in the San Gabriel Valley near the Santa Fe Dam, through the San Gabriel Valley, just past the Whittier Narrows Dam, down to about the 5 Freeway—was built with a soft bottom. We’ve taken advantage of that and installed rubber dams at strategic locations along the river. We inflate those rubber dams during storm events, and use the river itself as additional groundwater infiltration basins during the more frequent routine storm events. That’s been extremely successful in increasing our overall capability. 

However, you have to have the ability to infiltrate the water when you use those rubber dams. The LA River, for example, with the exception of the portion of the river adjacent to Griffith Park, has a concrete bottom. The challenge is looking at other opportunities along the LA River where you can not only retain the water, but also infiltrate it once it’s captured.

Let’s discuss your responsibilities for discharge and water quality in terms of storm water in your system. 

The Flood Control District, together with the 85 other municipalities in the county, are all working together to deal with the issue of improving storm-water quality. The current Municipal Storm Water Permit issued by the Los Angeles Regional Water Quality Control Board has encouraged watershed-wide collaboration to develop plans to improve water quality. Around 19 watershed groups have formed over the last several years to look at the water-quality requirements on our various watersheds and to develop projects and programs needed to meet the water-quality standards, ultimately improving the quality of water in our lakes, rivers, and the ocean. 

The Flood Control District is working in partnership with cities in developing these watershed plans. The various municipalities within the county and the unincorporated areas are all responsible for improving water quality within their respective watersheds.

We just recently reached a milestone in our storm-water quality planning efforts: All of the watersheds have now completed Enhanced Watershed Management Plans, which look at opportunities to use storm water as a resource. They allow us to consider opportunities to install projects that capture storm water, and, either through infiltration or reuse, not only deal with quality issues, but also deal with increasing our local water supply sustainability. Those plans have been submitted to the Regional Water Quality Control Board for approval. Having more than 70 municipalities in the district collaborate together and develop these watershed plans has been a major milestone in the region. It hasn’t been done before. 

The Regional Water Quality Control Board, in the way they framed our most recent permit, provided incentives for cities to collaborate in developing these watershed-wide plans. Watersheds and water don’t respect political boundaries. For us to be successful, we have to collaborate with other municipalities within our watershed. That’s what’s happening in the region now, and we’ve been recognized for the level of cooperation occurring here to tackle watershed planning.

Let’s close by noting that time and money are always the big constraints for an agenda as large as yours. Over the course of 2015-2016, what are the priorities of your department?

Our priorities fold back to the two primary core missions of the Flood Control District that we manage here at Public Works: to provide flood risk management to our communities and to capture storm water for reuse in our local water supply.

All of the projects and programs that we’ve been working on for many years, and that we have in the works with our partners, aim to meet those two goals. 

We’ve spent tremendous monies ensuring that we continue to be able to provide the level of flood risk management that we’ve been able, historically, to provide. That meant modernizing our dams and our flood-control channels. We’ve also been developing many projects to increase our ability to provide storm-water capture for groundwater recharge. We have many more in the future. That is the emphasis of our local water supply sustainability efforts.


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