From the Mountains to the City:
Los Angeles River Environmental Conditions, Water Quality, and Biodiversity
By Jisun Park, President of the Crean Lutheran Heal the Bay Club
Water in LA, Then and Now
The Los Angeles River has had a long, symbiotic relationship with humans, dating as far back as the establishment of the Gabrielino Indians to the settlement of early Spanish explorers. However, more recently, the Great Flood of 1938 in Los Angeles devastated the area resulting in massive property damages and many casualties. The city of Los Angeles devised and initiated the L.A. River Master Project, a large undertaking with the ultimate goal of preventing future catastrophes such at the Great Flood. The project included plans to remodel the river with concrete flooring to help guide the flow of water, and high concrete banks to protect the surrounding communities from flooding during heavy rains. This concrete river flows through eighteen Southern California cities, in some of the most urban neighborhoods.
Though the L.A River Project has protected these communities from further damage, it has since created an entirely new set of problems for the river’s ecosystem. Los Angeles receives the majority of its precipitation three months of the year. During the remaining nine months, in most areas, the water in the river dried up, but left other areas stagnant resulting in highly contaminated water. To combat this, the local government developed another program to push fresh, clean water down the river, increasing the water levels during times of drought, promoting the flow of water and helping to reduce contamination levels.
My Path to River Research
In 2012, during the Summer Program with Heal the Bay, I began to gain interest in the environment, but more specifically the Los Angeles Rivers and its ecosystem. A year later, in the summer of 2013, we ventured on a trip to South Korea to visit two very interesting rivers, the Cheonggye and Oncheon Rivers. Both rivers, once heavily polluted by their local communities, have since been revitalized through government intervention and rehabilitation efforts.
Our trip to these Korean rivers along with the L.A. River Revitalization Project, inspired me to begin a yearlong research and analysis project studying the water quality, the biodiversity and the environment of the Los Angeles River.
From the Mountains to the City
The study on the L.A. River began in November of 2013. Five different sites of the river were selected including Big Tujunga Creek, Hansen Dam, Taylor Yard, and Olympic Blvd, containing examples of environmentally healthier mountainous regions of the river, and gradually working towards more heavily urban, artificial sections of the river. The project focused on comparing, between the different sites, the quantity and diversity of the flora, air temperatures, water temperatures, and other water quality parameters including pH and nitrite, and dissolved oxygen levels.
During the study, as expected, all sites recorded mean temperatures between 15 and 30 degree Celsius while the water depth fluctuated between the different seasons, displaying normal desert environment traits. During the rainy seasons, nitrite levels rose though the other water parameters studied stayed in normal healthy ranges. Nitrite level increases during the rainy season were most likely attributed to storm drain runoff mixed with man-made chemicals such as fertilizer.
Monitoring the algae, invertebrates, and microorganisms within the water helped define the overall health of the river. By examining and identifying the number of plants, we were able to identify that the more natural and environmentally friendly sites had not only a higher count of individual plants, but were also taller and more dense, while sites with heavier amounts of concrete in more urban neighborhoods had smaller, fewer plants.
When comparing the two types of sites, those that were healthier and those that were not, it was found that water temperatures were lower, and in their normal ranges for the sites with higher plant counts, whereas sites with fewer, sparser plants had much warmer water temperatures.
A Better Water Future
The heavily concreted section of the river winds through the heart of Los Angeles, and because the city itself is heavily affected by the heat absorbed and released by the concrete, the study at the L.A. River helped demonstrate the existence of an artificial island of heat. The river and its surrounding areas sense abnormally warmer temperatures throughout the year had the river not had any concrete. However, as we saw with the rehabilitated rivers of South Korea, it is possible to reverse these consequences.
Only through a concerted effort by our local government and the citizens of Los Angeles, can we rid the river of the concrete while introducing an abundance of plants around the river, sparking a dramatic change in the perception of tourists while helping to reduce energy consumption, improving the quality of life for those living around the rivers, and helping indigenous species of plants and animals to thrive.
To download the full presentation of Jisun Park’s research project, please follow or share this link: http://www.kobebistro.com/LARiverResearchV2.pptx
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