January-February 2011

Los Angeles River Revitalization

More than 200 individual projects help save a threatened river.

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The Los Angeles River begins in headwaters in the San Fernando Valley, where Bell Creek and Calabasas Creek, also known as Arroyo Calabasas, meet in the city of Canoga Park. The river flows only 52 miles to Long Beach, but in its course it falls 795 feet in elevation. That’s 150 feet more than the Mississippi drops in its entire 2,350 miles.

In southern California’s arid climate, especially during drought years, some sections of the Los Angeles River are barely damp for months on end. But when heavy storms occur, this river carries 183,000 cubic feet of water per second and dumps it into the Pacific Ocean. That flow rate is 14 times the flow rate of New York’s Hudson River.

The watershed of the Los Angeles River covers 871 miles, from the Santa Susanna Mountains to the west, the San Gabriel Mountains to the north and east, and the Santa Monica Mountains and Los Angeles coastal plain to the south. The upper half of the watershed includes forest and open land. The lower portion is highly urbanized with commercial, industrial, and residential sections. Its runoff teems with bacteria, metals, trash, ammonia, algae, oil, pesticides, and other pollutants.

Once the river ran free and looked very different. It provided water and food for the Gabrielino Indians and other tribes for hundreds of years before Spanish explorers and settlers arrived. The Native Americans hunted and fished along its banks, beneath large oak trees. Some of their villages were located in the San Fernando Valley and Elysian Valley in what is now the city of Glendale.

The location of the river, with water for people and agriculture, meant that the city of Los Angeles was founded there in 1769. The river was the sole source of fresh water for residents of Los Angeles until the Los Angeles Aqueduct was built in 1913. Although the river does still supply some water for residents, most of what the city needs is now conveyed by several aqueducts, which are taxed by a growing population. As an alluvial river flowing across a flood plain, the Los Angeles River had a path that was unstable and unpredictable. Major floods occurred in 1835, 1862, 1903, and in other years, often changing part of the river’s course. Floods in the 1930s took the lives of 85 people. The most damaging flood occurred in 1938.

In its aftermath, the US Army Corps of Engineers began to lay the concrete that eventually covered most of the river’s bed and banks. When the massive flood control project was finished, the only parts of the river that were not paved over were a 3-mile section south of Griffith Park known as the Glendale Narrows, its last few miles in Long Beach, and about 3 miles near the flood control basin behind the Sepulveda Dam near Van Nuys.

Although the project saved lives and prevented property damage, most of the river and surrounding land was turned into an eyesore. The river was trapped in concrete channels—made from 3.5 million barrels of concrete—belowground or below freeways, out of sight and out of mind.

The channelization of the river by the Army Corps of Engineers succeeded in controlling flooding during heavy storms in the winter months. After 30 years of channelization, the river was renamed the Los Angeles River Flood Control Channel—no longer a river, not even in name.

If citizens of Los Angeles remembered the river at all, they thought of it as the scene for car races in movies. Terminator 2 and Grease are two of the films that include car races filmed along the river’s dry, isolated concrete channels.

In the 1990s, the Los Angeles River made American Rivers’ list of the country’s 20 most threatened and endangered rivers—six times. In 1995, it was named the second most endangered river in the country.

In recent years, as public awareness of protecting the environment and mitigating stormwater pollution has grown, various groups of citizens and public officials have started working together to bring back the lost river and clean up its waters. These groups include Mountains Recreation and Conservation Authority, Santa Monica Mountains Conservancy, Friends of the Los Angeles River, North East Trees, The River Project, Tree People, the Arroyo Seco Foundation, the Coastal Conservancy, the Trust for Public Land, and the city and county of Los Angeles.

“Over two hundred years ago, the river gave life to the City of Los Angeles. Thanks to the efforts of countless Angelenos, we’re giving life back to the river, renewing her, transforming her back into the enchanted place she once was,” said Los Angeles Mayor Antonio Villaraigosa as efforts got underway.

In 2002, under the leadership of Los Angeles city councilmember Ed Reyes, the city council established the Ad Hoc Committee on the Los Angeles River. This committee created the Los Angeles River Revitalization Master Plan (LARRMP) in 2007. LARRMP is a long-range guide to the ultimate goal of creating green spaces, trails, bike paths, and parks connected along the entire river.

The LARRMP won an American Society of Landscape Architects Honor Award in 2009. Firms involved in creating the plan included Mia Lehrer + Associates, Civitas Inc., and Wenk Associates, all of Los Angeles.

Reyes says the revitalization project “will transform the neglected backyard of the Los Angeles River to a front yard of parks and bike paths, creating something in which we can all take pride.”

Reclaiming the entire natural river will, of course, take years. The project is being achieved by reviving existing natural areas and returning former urban areas to their natural states, one by one, like adding each bead on a necklace of emeralds.

“Slowly we are changing Los Angeles, making it a better place. We’re creating parks and public places laced with trails and trickles of water,” says Lynne Dwyer, principal with BlueGreen Consulting and landscape architect for a number of river revitalization projects.

Parks are a key component of the revitalization. Some of these parks are small enough to be called “pocket parks.” Others are large enough to include multiple fields for soccer and other sports.

In between are neighborhood parks, not large enough for sports fields but big enough to provide natural landscape for residents in all-concrete urban neighborhoods, habitats for birds and other wildlife, and the means to increase water supply and decrease water pollution.

One of these parks along the Los Angeles River Greenway is Marsh Park. It is located north of downtown Los Angeles, in the part-industrial, part-residential neighborhood of Elysian Valley. Dedicated in May 2006, Marsh Park measures about 3 acres.

Artists from ArtShare designed Marsh Park’s whimsical playground with its turtle, snake, and frog statues for children to climb on. Youth from the LA Conservation Corps planted native plants throughout Marsh Park. The total cost for the project was approximately $985,000, with $288,000 of that amount from park bond (Proposition A) funds.

 

Photo: BlueGreen Consulting Cross section of planned 8th Street Park, part of the Los Angeles River Greenway

Runoff from the neighborhood now infiltrates into a natural land depression in Marsh Park. Workers removed the concrete storm drain that lay beneath the park and graded the land to form the depression. Runoff can also infiltrate between rocks and sandy areas among the native plants.

“Marsh Park is a model for every public property near the Los Angeles River. While cleaning polluted water runoff from city streets before it goes into the river, we bring nature back into neighborhoods and create parkland and recreational opportunities in densely populated urban areas where they are needed most. Joint use, multi-benefit projects give the public the most for its money,” says Joseph T. Edmiston, executive director of the Santa Monica Mountain Conservancy.

In another section of the Los Angeles River’s watershed lies Tujunga Wash, one of the river’s largest tributaries. Tujunga Wash flows southwest and south from Angeles National Forest. Flowing into it is Pacoima Wash, in the city of San Fernando. Pacoima is a Native American word meaning either “the entrance” or “flowing waters.”

Pacoima Wash will also have a park that is part of the Los Angeles River Greenway. 8th Street Park, which will measure almost 5 acres, was scheduled to open in May 2009. It was to be built in the city of San Fernando for $2.2 million, including $587,000 in Proposition 50 funds, a joint project of the city and the state agency Mountains Recreation and Conservation Authority (MRCA). However, when California Governor Arnold Schwarzenegger froze funding on all Proposition 50 projects, 8th Street Park was only partially finished. Its completion date is uncertain.

The innovative design will feature two small circular plazas called placitas, which will be located at the ends of the streets leading to 8th Street Park. The placitas will hold large native sycamore trees and will act as intake points for stormwater runoff from the surrounding neighborhood of 33 acres.

Grading the land along Pacoima Wash will allow for runoff detention and infiltration. Trash screens on the drain inlets and sediment traps will capture debris from the incoming runoff. Gravity will send the runoff through a sand filter system, then into a vegetated bioswale, then into an infiltration pond. An overflow channel from the infiltration pond will send extra runoff into Pacoima Wash.

At least 75% of the water in the park will recharge the aquifer. Native plants, including yarrow and sedge in the lawn areas, attract birds and other wildlife. And in an urban, park-poor neighborhood, the residents will have benches for passive recreation and access to the hiking trail alongside
Pacoima Wash.

Dwyer notes that her BlueGreen Consulting partner, Dr. Martin Kammerer, a fluvial geomorphologist, designed the stormwater treatment system. “The entire park is designed as a BMP [best management practice],” she adds.

Some of these riverside parks have names that allude to the wildlife native to the Los Angeles River watershed, such as Duck and Egret. Rattlesnake Park is named for the nest of rattlesnakes uncovered during construction. It features a graceful serpentine seating wall and the Great Heron wrought iron gates.

Steelhead Park, in the Elysian Valley, is within the Glendale Narrows section of the river. This part of the river was not paved over, so it has a natural bottom. Tall trees line its sides, and wildlife is abundant.

With its name and the decorative wrought iron entrance gates, this park recalls the steelhead trout that once were plentiful in the river. Now the steelhead is a symbol for the revitalization of the river.

An outdoor classroom amphitheater, native plantings, and access to the trail alongside the river let Steelhead Park bring nature to the residents of the surrounding urban area. It was developed by MRCA and North East Trees.

The city’s Department of Public Works retrofitted Steelhead Park to accept and treat runoff from surrounding areas of public property and Oros Street, through an infiltration trench (4,325 cubic foot capacity) beneath the park. Oros Street was the first “Green Street” project in Los Angeles. That designation also meant that it was the first neighborhood subwatershed that would no longer send polluted runoff to the Los Angeles River. Instead, runoff is captured and cleaned through soil infiltration and vegetated bioretention. Some runoff from the 17 private residences flows into filtration system strips or trench drains that were placed across the driveways.

The city constructed stormwater gardens, also called rain gardens, along Oros Street in areas in the parkway. Each garden is large enough to accommodate runoff from two or three residences during a rainfall event of ¾ inches.

But “between the generous safety and the conservatism of the county’s method for estimating runoff volumes, the project is capturing the first 1 to 1¼ inches of flow before it overflows to the river,” says architect Holly Harper, senior designer with the Watershed Rehabilitation Program for North East Trees.

Harper says that the most challenging part of the Oros Green Street—Steelhead Park project was “the lack of standard plans for any of the elements in the parkway rain gardens.” The designers forged their way into new territory. “We formed an amazing partnership with a working group within the Bureau of Street Services with the ability to self-permit, on developing the final plans and building the street portion,” she explains.

City procurement processes countered the idea of using permeable paving in the project, she says: “Having only one type of concrete or asphalt in all of their yards is preferable to the alternative of keeping a separate, special pile of permeable concrete, unit pavers, etc. on hand for possible repairs.” But the desired result was achieved differently.

 “We just reversed the slope of the walkway inward toward the planting pocket so that the usual old concrete collects water and sheds it toward the stormwater garden,” explains Harper.

 “The partnership with the Bureau of Street Services staff in the working group was essential,” she emphasizes. “We just had to find a path through those constraints by understanding why we were being told ‘no’ and then proposing alternative solutions.”

Dedicated in July 2007, Oros Green Street was also the first Proposition O-funded project in the city.     

Passed in November 2004, Proposition O authorizes the city of Los Angeles to issue a series of general obligation bonds for up to $500 million for projects that will protect public health by cleaning up pollution, bacteria, and trash in the city’s waterways, ocean, and beaches, in order to meet Federal Clean Water Act requirements.

Proposition O funds can also be used for purchasing or improving property to protect water quality; provide flood protection; increase water conservation, habitat protection, and open space; and capture, clean, and reuse stormwater.

Another city project that will keep runoff out of the Los Angeles River is the Elmer Avenue Neighborhood Retrofit. Located in the northeast Los Angeles neighborhood of Sun Valley, Elmer Avenue had had flooding problems for many years.

When Elmer Avenue was scheduled for resurfacing, the city’s Bureau of Sanitation, Bureau of Street Services, TreePeople, and the Los Angeles San Gabriel River Watershed Committee joined forces to create a retrofitted street with an enhanced ability to handle stormwater runoff.

The major component to handle runoff on Elmer Avenue is a large infiltration system below the roadway. Two underground infiltration galleries completely handle runoff from a 37-acre drainage area during a two-year storm event. One gallery measures 250 feet long by 36 feet wide. The other gallery is 100 feet long by 36 feet wide.

Wing Tam, P.E., assistant division manager in the Watershed Protection Division of the city’s Bureau of Sanitation, explains that runoff is pretreated by utilizing two catch basins for sedimentation and trash as well as through vegetated rain gardens and biofiltration swales.

Low-impact development (LID) strategies include five solar streetlights, vegetated swales, rain gardens, and increased use of permeable surfaces for driveways and walkways. Residents on Elmer Avenue have replaced old landscaping with drought-tolerant native plants and added rain gardens, bioswales, rain barrels, and driveway French drains.

The most challenging part of the project, Tam says, was “to find an entire city street block with willing participants to be involved in this project, to be the first of its kind in the city using low-impact development practices that include rainwater harvesting, flood management, habitat enhancement, and energy efficiency.”

This project aligns well with the WPD’s overall strategy. “WPD embraces a decentralized stormwater management system in order to meet stormwater quality standards and to provide additional water supply resources utilizing green natural systems for a sustainable and healthy environment,” explains Tam.

Compton Creek is a southern tributary of the Los Angeles River. Treating polluted runoff in a highly urbanized area before it reaches the river is the purpose behind the $100,000 Augustus F. (Abe) Hawkins Wetland Habitat, the first constructed wetland in the city. It also serves to control flooding in downstream communities.

Completed in 2005, the wetland habitat is part of the 8.5-acre Augustus F. (Abe) Hawkins Nature Park, which used to be a cement pipe storage yard. It measures 0.5 acre with an additional 0.5 acre of storage area to handle runoff from bigger storms.

Depth ranges from 5 to 10 feet year round. This freshwater marsh is an open-water mosaic rather than isolated bodies of water. An impermeable liner reduces water loss from downward infiltration. The surrounding riparian wetland habitat includes cottonwoods, willows, sycamores, California rose and blackberry shrubs, cattails, and yellow pond lilies.

 

Photo: Mountains Recreation and Conservation Authority Marsh Park entry

More than 230 separate projects are, or will be, part of the river’s revitalization. These projects are separated into five-year completion intervals ranging from current to 50 years out.

 

Photo: Mountains Recreation and Conservation Authority Runoff from the neighborhood now infiltrates into a natural land depression in Marsh Park.

These future projects vary greatly in size and format, but, like pieces in a jigsaw puzzle, each of them has a role to play in completing the greenbelt.

 

Photo: Mountains Recreation and Conservation Authority This freshwater marsh is an open-water mosaic rather than isolated bodies of water.

In September 2009, the city approved the purchase of the 6.3-acre industrial site of a former dairy, in the Albion neighborhood of Lincoln Heights, 1.5 miles northeast of downtown Los Angeles. The city bought the property with $17.56 million dollars of Proposition O funds. For decades the Swiss Dairy Company used the location as a distribution and warehouse center. These operations will continue until the dairy’s lease expires in 2011.

Preliminary work on the new park has begun. Its final design, approved in January 2010, includes an amphitheater, skateboard park, baseball diamond, and passive recreation areas. Developing the park is expected to cost $5 million, paid by the California Department of Parks.

Stormwater management features will include permeable paving in the parking lot, a seasonal bioswale, infiltration areas near Albion Street and the future athletic fields, open green areas, and widespread use of native plants. Educational signage will be installed to explain how these features work to clean runoff from the surrounding urban neighborhood of 254 acres.

Councilmember Reyes has been involved in river issues for years. He says that this first river land purchase by the city “is significant also because it demonstrates a desire and commitment to create open space for our neighbors along the L.A. River.”

The future Albion Dairy Park, adjacent to the river, will be a key link in the greenbelt alongside the Los Angeles River. When completed, it will connect regional open space of existing properties. These existing green spots include the Downey Recreation Center, Downey Child Care Center, and Los Angeles State Historic Park.

The Los Angeles Gateway Authority received $5 million of federal stimulus money to install about 12,000 catch basin inserts into all publicly held storm drains that lead to the river, in each of the 16 cities on its banks. Proposition O funds will pay for screen covers in high-trash-generating areas.

Other current and future Proposition O projects include the improvement of the 33-acre parking lot at the Los Angeles Zoo, which drains directly to the river. Bioretention cells, swales, native plant landscaping, and permeable pavement will let runoff infiltrate onsite. Estimated cost is $14 million.

The cleaning and restoration of Echo Park Lake is expected to cost over $84 million and take two years, to be finished in 2012. The 13-acre urban lake, with its beautiful lotus beds and 16 surrounding acres of open space, is one of Los Angeles residents’ treasured recreational places. It was built as a water supply reservoir in the 1860s.

Today, the lake serves as detention basin for stormwater runoff and waterfowl habitat. The project will include the addition of grassy swales, porous pavement, wetlands, and weather-based irrigation systems, as well as draining the lake and removing contaminated sediments and improving storm drain inlets.

The North Atwater Park Expansion and North Atwater Creek Restoration projects are both scheduled for late 2010 to fall 2011. Total cost is estimated at $4.2 million, with $2.2 coming from Proposition 50 funds. The park will add 3 acres of green space by the river. Wetlands will be restored to treat runoff from the North Atwater Creek storm drain, which receives runoff from about 40 acres of urban area.

Reshaping the streambed will provide flood protection by slowing down runoff. Native riparian plants and decomposed granite walkways will be added, along with permeable pavers in the parking lot. What was an all but vanished stream will be a small area of native riparian habitat and seasonal wetlands that help return the river to its native state.

Another future development and major section of the Los Angeles River Greenway is the Taylor Yard section, which will be developed by the city. The area is where the Portola expedition camped in 1769 and decided to call the valley that teamed with flora and fauna “Los Angeles.”

Land grants from the Spanish government led to family holdings. In the late 1890s, J. Harley Taylor owned the site. He owned a grocery and a milling company for animal feed, and he raised various crops on the property.

In the 1920s, Taylor Yard became a railyard when Southern Pacific moved its freight switching and repair operations there. These operations gradually ended in the 1960s and ’70s. Taylor Yard stopped freight switching in 1985.

A coalition of diverse community groups united to defeated attempts by corporations to develop the area. Part of Taylor Yard has been turned into a state park, Rio de Los Angeles.

Taylor Yard measures about 247 acres. With more than 2 miles of river frontage, the redevelopment of this land will have a huge impact on the river’s revitalization.

Stormwater management plans for the site include an infiltration swale, microbasin, and permeable material and gravel in the parking areas. Grassy swales, oxbow detention ponds, permeable materials on ball courts, and recycled water in a splash pad for young children will also be included.

From the smallest pocket park that residents are already enjoying to the grand possibilities that Taylor Yard holds, the Los Angeles River draws residents to it, just as it drew the first settlers. Residents of today and the future will have access to the river—without the flooding.

Members of the various groups which have worked on the revitalization of the Los Angeles River have been inspired by how much river revitalization has changed San Antonio, Denver, and other cities. They visited many of cities with successful river revitalization programs, including Seoul, Korea.

Like the Los Angeles River, Seoul’s Cheonggyecheon Stream had been encased in concrete for years. A two-year, $384 million project returned the river to its natural state and developed adjoining land into a park and recreation area. The project required that one of Seoul’s major freeways be permanently closed.

In February 2010, a special ceremony to inspire the revitalization of the Los Angeles River was held at Taylor Yard. Korean leaders poured a vase of water taken from the Cheonggyecheon Stream into the Los Angeles River. Cosponsored by Friends of the Los Angeles River and the Korean Cultural Center, the event was called a Sister River ceremony.

Author's Bio: Margaret Buranen writes from Lexington, KY, on the environment and business, for several national publications.