Posts tagged Lower Los Angeles River

Image Credit: Jenni Zell

AHBE interns, W. Zhou (left), Y. Tian. Image credit: Linda Daley

This past summer we had the pleasure of working with our interns to develop a speculative proposal to advance the Rio Hondo Confluence, which is a signature strategy identified in the Lower Los Angeles River Revitalization Plan (LLARRP). The LLARRP is an important document that will guide the transformation of the Lower Los Angeles River for decades. Our independent speculative project, outlined below, integrates strategies providing green infrastructure, ecological habitat, recreational and cultural use.

We selected one opportunity area identified in the LLARRP, the confluence of the Lower Los Angeles River and the Rio Hondo in the city of South Gate, as the focus of our separate investigation and developed a proposal which we entitled River Commons. The Rio Hondo Confluence is a place that presents significant possibilities to transform into both a cultural and ecological asset for the community.

Credit: Regional context and other graphics in post are by AHBE.

The 254-acre site has a complex history. In addition to hydrologic flows converging at this location, transportation and energy flows converge along the 710 Freeway and Imperial Highway. Although it is within a 30-minute walk of several cities including Compton, Lynwood, and Paramount, the flows of traffic, power and water have isolated people and adjacent communities from one another and from the natural resource of the Los Angeles River.

Image Credit: Calvin R. Abe

Located in a landscape where grizzly bears once fished for steelhead trout, the seasonally riparian and upper terrace upland habitat of the Rio Hondo Confluence provided critical habitat functions of the Los Angeles River ecosystem. Our River Commons proposal outlines building blocks to re-connect people and nature by interweaving cultural and natural systems. In addition, the proposal prioritizes the establishment of physical connections, habitat connections and ecological functions to the site while also providing support for wildlife species, stormwater capture and cleaning and new recreational amenities.

The concrete lined river channel has provided flood protection for decades and adjacent freeways have sped up the transportation of people and goods, but the benefits come at the tremendous cost of dividing communities, destroying significant habitats, and breaking ties of the surrounding people to the historic cultural and natural resource of the waterway for food, leisure and health. River Commons tackles the seemingly intractable problem of choosing between flood protection and economic progress and ecological and community health and vitality. Transforming what is currently a single purpose flood control channel into a civic asset, River Commons proposes to advance a signature strategy identified in the LLARRP.

Building Blocks Approach

The building blocks we explored in River Commons can be tested at the Rio Hondo confluence site and adapted and applied to other Los Angeles River and adjacent sites. We identified four key building blocks in our proposal.

  • Temporary and seasonal in-channel recreation is the first building block, which will build momentum for future projects. It will increase awareness of the river channel as a community resource and provides unique experiences not currently available in nearby parks.

  • Levee terracing will provide seasonal access to the river channel during dry weather and new in-channel habitat spaces.

  • Low-flow channel modifications: Creating meandering and multiple crossings of the low-flow channel create water movement and attraction to the water’s edge. Installing ecological concrete and widening the channel enhances biological value by supporting the growth of organisms including targeted fish species.

  • Bridge crossings to connect pedestrian, equestrians and bicyclists: Multi-modal channel crossings provide much needed connections of communities to one another, the river and river adjacent regional trail systems, along with viewing opportunities of local mud swallows.

Site Specific Design Strategies

Charles S. Dwyer, USACE. Credit: Linda Daley

Hydrological modeling and engineering principles were integrated into the analysis and design phase for our selected area through collaborations with local civil engineers and the US Army Corps of Engineers (USACE). We acknowledge and thank USACE’s Charles S. Dwyer (shown at right) and Reuben Sasaki for giving generously to our investigation in terms of their time, LA River knowledge, and technical review and feedback.

By closely collaborating with hydraulic and civil engineers, we received feedback on the draft building blocks to determine the feasibility of our proposals. This collaboration was critical in identifying and evaluating potential design strategies, a few of which we share below.

  • Treating stormwater before it enters the river is key to improving water quality in the river and ocean. River adjacent properties can be utilized to collect and filter runoff while also increasing habitat and at some sites, recharging underlying aquifers.

  • Expanding the river channel to the bend in the 710 freeway presents a unique opportunity for adding substantial new habitat areas hydrologically connected to the LA River ecosystem. This area would flood during design storm events, but regenerate naturally.

  • Taking advantage of the water collected by a downstream rubber dam and utilizing control gates and drainage lines through the levee, river adjacent fisheries can be created to move water and create a hydraulic connection to the river.

  • Horse Camp at the Hollydale Park expansion builds on the rich equestrian culture in the area and provides a revenue source and river trail rides, connecting people and nature to one another and their river.

In developing our design solutions, we were guided by cultural investigations which foster an interconnectedness between the surrounding community’s citizens, environment, and cultural resources. By linking public health, air quality improvements, energy and water demands and supply, accessibility and mobility improvements with sound green infrastructure strategies, the River Commons proposal is an additional resource for community members and agencies to help visualize and build support for future projects.

Image credits: Wendy Chan (above left) and Jenni Zell (right)