Urban Runoff In The LA River

The Los Angeles River has long suffered from a major problem: urban runoff. It affects the river every day, and most of us in Los Angeles County contribute to it unwittingly with a variety of items, everything from a dog’s animal feces to car oil, fertilizers, and many other chemicals located in and around the house.

Water flows into the Los Angeles River from over 830 square miles of land, which can include a lot of dogs, cars, and gardens.

Fertilizers enter the Los Angeles River when fertilized plants are watered and the excess fertilizer enters the storm drains and then into the river. Farmers and residential gardens routinely use chemical fertilizers to make their plants look and grow better, but much of this washes off the land and into storm drains, according to the federal Environmental Protection Agency (EPA).

While fertilizers provide essential food nutrients such as nitrogen, phosphorous, and potassium, they have negative consequences. Fertilizers can release greenhouse gases, especially when combined with water, as happens when they enter the Los Angeles River.

Nitrates and phosphates are common elements that run off from fertilizers into the storm drains in the watershed area of the Los Angeles River. These chemicals stimulate growth of aquatic plants such as algae. Excessive amounts of algae clog waterways, use oxygen when they break down, and prevent the amount of light that reaches deeper water. All of these effects make life more difficult to sustain when algae is built up.

According to Leslie Laudon, a State Water Resources Control Board manager, “The biggest challenge is fighting diffuse pollution sources,” such as a fertilizer that comes from a lawn in the San Fernando Valley and ends up in the Los Angeles River.

Fertilizer entering the Los Angeles River causes another major problem- weakening fish respiration. With the water polluted, the fish have no choice but to breathe the contaminated water, which ultimately makes it more difficult to breathe after the toxins from the fertilizers have entered their body. According to David Keune, a marine biologist, “Once a fish has breathed fertilizer contaminated water, it will most likely die within 2-3 weeks.”

In addition; fertilizer runoff entering the Los Angeles River lessens terrestrial plant efficiency. Botanist Nadia Oggiano said, “When there’s an excess of algae in a river, the amount of oxygen decreases drastically because the algae use a large sum of oxygen.” Without enough oxygen, the terrestrial plants die because of suffocation. Algae takes away a tremendous amount of oxygen away from other organisms in the river. Also, with an abundance of algae, the depth of the water cannot be perceived because of how dense algae can get.

Fertilizer runoff causes a lowering of the water table and the likelihood of flooding to increase. From 1998 to 2003, the water table level for Los Angeles County dropped four feet, Los Angeles Regional Water Quality Board (LARWQCB) officials said. With that dramatic of a drop, the concentration of fertilizers only increased. Also, flooding has a higher chance of occurring, according to the Los Angeles County Department of Public Works. When fertilizers stay on a surface, they lower the permeability, and thus cause water to not sink into the ground, but to flow across the top of it and increase the likelihood of a flood.

Alicia Katano, education director for Friends of the Los Angeles River (FoLAR) said that urban runoff “is usually the worst a week after a rain storm,” as fertilizers are swept into the storm drains by the rain.

While 26 million gallons of water in the Los Angeles River is treated at the Tillman Reclamation plant per day, in Van Nuys, none of the urban runoff is treated at the Tillman plant, or any other water reclamation plant.

Because the city of Los Angeles has such a high population, it would make sense economically to use the water from the Los Angeles River as a source of drinking water, but because of the effects that fertilizers can have in the runoff, the river becomes polluted to the point where the river water cannot be used as a source of drinking water.

According to the Los Angeles River Revitalization Master Plan, “The Regional Water Quality Control Board, Los Angeles County Department of Public Works and some cities have sponsored the stenciling of storm drain inlets to raise awareness of water quality issues.”

Trey Block