Water reuse and river flows: What can we learn from the LA River?
March 04, 2022
River revitalization takes many forms. In Los Angeles, studying the impact of instream flows helps us look to the future.
Water is a scarce and valuable resource in drought-prone Southern California. As water reuse and recycling increases across the region, it creates a conflict in priorities. On one side, there is more water for people. On the other, there is reduced water for recreation and nature. Local agencies and water districts are challenged with balancing and prioritizing the needs of people and nature.
The Los Angeles River is a prime location to better understand and establish instream flow requirements. The California State Water Resources Control Board, the Los Angeles Regional Water Quality Control Board, and the Southern California Coastal Water Research Project¡ªin cooperation with local municipalities¡ªinitiated the Los Angeles River Flows Project in 2019 to better evaluate the cumulative impacts of potential flow reductions to the LA River. The project provides a science-based approach for assessing the flow necessary to sustain beneficial uses in the river.
The desired project outcome is to establish technically sound flow recommendations and evaluate the consequences of alternative flow scenarios for the LA River. It may also serve as a model for assessing similar situations in other California river systems.
The Los Angeles River runs 51 miles through mostly concrete channels to protect local neighborhoods from flooding.
A thriving river and a sustainable water future: Can the City have both?
A healthy river, lush with wildlife. A future in which the City meets its own water needs without importing from outside. The Flows Project impacts how we balance those two priorities.
The Los Angeles area has essentially two weather seasons¡ªwet and dry. It¡¯s the same throughout much of California and the West.
During the dry period, about 90% of the water flowing into the LA River is treated wastewater discharged from three wastewater treatment plants from the cities of Los Angeles, Burbank, and Glendale. Additionally, local runoff represents the remaining 10%.
With Los Angeles Mayor Eric Garcetti pledging to recycle 100% of the City¡¯s wastewater by 2035, and the City striving to improve wastewater recycling, there is an undeniable ¡°push and pull.¡± On one side is environmental preservation for one of the City¡¯s most iconic landmarks. On the other is a sustainable water future for America¡¯s second largest city.
If local agencies follow through on their most ambitious plans to capture more stormwater and reuse treated wastewater, the 51-mile-long Los Angeles River could dry up. Yes, really. That, in turn, could make the river less hospitable to the plants, birds, and other wildlife that call it home.
The goal of the Los Angeles River Flows Project is to better evaluate the cumulative impacts of potential flow reductions to the river.
Just like a river that has many twists and turns, there are multiple factors when looking at the LA River¡¯s future. The Flows Project focused primarily on the river¡¯s biological resources.
The project helped determine the animal and plant species and habitats that contribute to the fabric of the river. It also considered which flow metrics are impacted by what seasons, as well as how changes in flows alter recreational opportunities.
When looking at aquatic life, the Flows Project considered hydrology models, hydraulic models, and water temperature models. It investigated habitats for cold water migration, wading shorebirds, freshwater marsh, and more. It looked at the impact of existing species and possibly reintroducing missing species¡ªlike the Southern California steelhead trout.
At the end of the day, it¡¯s a balancing act. The goal is to recycle enough wastewater to enable local cities to scale back on their reliance on imported water, while protecting the local environment and the recreational opportunities that surround it.
Revitalizing the LA River while maintaining its roots to LA¡¯s culture
About a million people live within one mile of the LA River, which mostly flows through a concrete channel. The river was channelized to protect lives and property from flooding during the late-19th through mid-20th centuries, and it continues to serve flood-risk management purposes today. The river doesn¡¯t look or function the same as it did before. But it serves a vital purpose.
There are multiple master plan studies focused on the LA River. The recent Flows Project adds valuable insights on what the river¡¯s future might look like.
Sadly, the LA River has largely been separated from the area¡¯s social, cultural, and ecological communities. In many respects, we have historically neglected the river since most of the properties along its banks do not face it. Too often, we simply view it as an eyesore.
There are multiple master plan studies focused on the LA River. The recent Flows Project adds valuable insights on what the river¡¯s future might look like¡ªespecially as we consider potentially lower water flows. The nexus between the Flows Project and master plans is the future.
The development community, local cities, and others want to build new facilities, features, and amenities as the LA River is reconditioned. One example is the Taylor Yard G2 project area, which was first identified as a priority in the LA River Revitalization Master Plan in 2007. G2 was a portion of the original 244-acre property owned by Union Pacific in the Northeast Los Angeles neighborhoods of Glassell Park and Cypress Park.
The City of Los Angeles Bureau of Engineering is leading the Taylor Yard project. The project would address park needs and access to the river through creating a publicly accessible open space, which would also provide native habitat.
The Glendale Narrows portion of the LA River, where popular recreational activities include bird watching, kayaking, and fishing.
How river flows impact river revitalization
The grand vision is to transform the river from a concrete conveyance channel into a premier riverfront with a myriad of uses. Nearby residents will enjoy housing, parks, retail/commercial, and recreational opportunities. There is the hope of a pedestrian and bike path that runs the river¡¯s entire length.
Revitalizing an urban river is not a new idea created in Los Angeles. Many cities around the globe have done it. What, perhaps, makes the LA River¡¯s story different comes in the extraordinary diversity and density of people that are both engaged with and impacted by the effort.
River flows are just one piece of the puzzle. But they are an important piece, especially as we continue to deal with drought and water challenges. It¡¯s exciting to see what happens next in LA and its impact on other rivers in California and elsewhere.