Keeping an Eye on L.A. River Vegetation and Habitat

After clearing at the L.A. River by Willow Street Estuary in Long Beach | Photo: William Preston Bowling

Just like the seasons, every year the Los Angeles County Department of Public Works (Public Works) comes around the soft-bottomed, engineered parts of Los Angeles's waterways and clears out the vegetation that's managed to survive. Public Works manages the day-to-day activities of the Los Angeles County Flood Control District (LACFCD). To most residents, The Public Works' actions seem part of regular maintenance, like mowing one's lawn, but conservationists beg to differ.

"If we continue to knock out vegetation, it might screw up the dynamic of habitat from evolving," says James Alamillo, Urban Programs Manager for Heal the Bay. For the fourth time in more than fifteen years, Alamillo will again testify in front of the Los Angeles Regional Quality Control Board (Regional Board), asking the authorities to take a second look at their management practices. Rather than issuing just another five-year permit for vegetative clearing, Alamillo is asking for more monitoring to determine just how much good this practice does.

"The type of clearing they do depends on the size of the area. In a small tributary, they can come and remove vegetation by hand," explains Alamillo. "In larger areas, like Compton Creek, they do front loads, bulldozers and whatnot. It's like a bomb has been dropped in this area. It completely decimates any community that existed."

The practice of river clearing has been in place since 1997, when Public Works proposed the clearing of 100 earth-bottom channels in anticipation of El Nino. By clearing the vegetation in these soft-bottomed, engineered portions of the river, Public Works sought to increase the flood capacity of the river.

Though it was a good practice for the time, Alamillo says that in the last decade the county has developed a better understanding of how to handle its water. Rather than quickly flushing it out to the ocean, Los Angeles now has a vested interest in trying to save as much water as possible. With this comes the task of revisiting its decades-old policy, but the right action cannot be undertaken without sufficient data, which has been missing from the equation for the last two decades.

Before and after clearing of L.A. River at Reach 25, by the Willow Street Estuary | Photos by William Preston Bowling

Before and after clearing of L.A. River at Reach 25, by the Willow Street Estuary | Photos by William Preston Bowling

The river clearing process is contentious for a specific kind of waterway, explains Alamillo. On one end of the spectrum, there is the completely natural waterway such as Malibu Creek. These habitats are well protected and extreme caution is taken when work is being done in those areas.

On the other end of that spectrum are the channels with no biological habitat or very little flora and fauna, just concrete and water. Those areas receive almost no environmental mitigation or oversight.

Then, there is the problematic middle ground, the semi-engineered waterways that have concrete sides, but have an active biological bottom that hosts native and non-native plants and animals. These, it seems, the county doesn't know what to do with.

"Though these areas may be semi-engineered, they have a lot to offer communities in the way of green space and recreational opportunities, habitat, water quality, and water infiltration," says Alamillo. "That's what we've been fighting tooth and nail for Public Works to see."

In response, Gary Hildebrand, Deputy Director of Water Resources with Public Works, says, "the challenge we face is the need to maintain channels so they can continue to carry the flow we need to provide regional flood protection. But we also recognize this vegetation is also habitat. We've come up with a vegetation management approach that we think successfully manages these two needs."

In cooperation with the Army Corps of Engineers, the Department of Fish and Wildlife, and the Regional Board, Public Works developed a maintenance plan in 1999 that specifies what actions to do on specific portions of the soft-bottomed rivers under this permit. It has been updated as more data has been available. For example, it says that its latest modeling techniques have surmised that more vegetation can be allowed to remain in some reaches of the river. "Moving forward, we'll work with regulatory agencies to revise our management plan to reflect that," says Hildebrand.

Friends of the Los Angeles River (FoLAR) has also come out with a statement advising increased caution when it comes to clearing these middle-ground waterways. It says that in some cases there is room for more vegetation to grow. In particular, in the Long Beach area of the Los Angeles River, is one of only three soft-bottomed reaches of the river. It can handle even more vegetation than is currently allowed to grow. The organization states in its letter:

"According to their mission, the LACFCD is tasked with not only providing the service of flood control, but protecting the aesthetic, recreational, and environmental use of each area they serve. Continuing to clear the vegetation in this reach is inconsistent with this policy. It is FoLAR's stance that mitigation is not being maximized in Reach 25."

"It's the same conversation I had when we declared the Los Angeles River a river and not a storm drain," says FoLAR founder Lewis MacAdams. "In this case, the LACFCD is refusing to consider it a river, but relegates it to being just a storm drain."

Before and after clearing of the L.A. River from Willow to PCH

Before and after clearing of the L.A. River from Willow to PCH

In Heal the Bay's comment letter to the Regional Board, the organization repeatedly requests the data from past two decades of vegetative clearing. Permits were issued in 1999, 2003, and 2009, which required monitoring prior to and after channel maintenance work. This data could be gathered to develop a trends analysis.

In a detailed response to the comments, Public Works has responded that their analyses from those various years was in the process of being analyzed, or was not required to apply for the permit.

Story continues below

Alamillo points out that an unchecked permitting process is not ideal. "They get to do this every year without having to do any mitigation." More importantly, river clearing permits such as this applies to soft-bottomed waterways in the Los Angeles River, Compton Creek, Santa Monica Mountains, and beyond. These permits have given Public Works permission to clear anywhere from 300 acres to more than 600 acres in a year. "That's a major construction project done every year, with no data to inform the public about its trends or policies."

Hildebrand says there are a number of ongoing studies on each of the rivers in which Public Works conducts soft-bottom clearing, including the Los Angeles River and the San Gabriel River. The agency has also used modeling techniques to predict how much vegetation can remain.

But Alamillo says modeled data isn't enough. "Modeled data can be completely arbitrary in terms of assumptions you put into it. You could run a hundred different models based on 100 different assumptions. You need hard data. We're 20 years into this, we should be able to look back, see based on rain events how many times have we been threatened with flooding -- is it 1 percent of the time? Or 99 percent of the time? -- and proceed from there."

Public Works isn't opposed to the idea. "We do believe there's a need to collect more information. We're fine with that," says Hildebrand.

Alamillo doesn't think the Regional Board would discontinue its practice of approving permits, but Heal the Bay and FoLAR at least want an accounting that was promised in the previous discussions but never materialized. "I want the Regional Board to start setting some goals. We probably won't be able to pull the switch and stop tonight, but at least we'll have goals to monitor for the next twenty years, so we know if we're going in the right direction. We need to start thinking more holistically and see the connections between the natural and the built environment."

River Clearing will be discussed at the Metropolitan Water District of Southern California on February 12. It is item 18 on the agenda. More details here. Find out more about the issue here.


We are dedicated to providing you with articles like this one. Show your support with a tax-deductible contribution to KCET. After all, public media is meant for the public. It belongs to all of us.

Keep Reading

Full Episodes