Understanding the Urban Influences on Santa Monica Bay, CA

INTRODUCTION

Brown pelicans at Malibu Creek Beach.

Santa Monica Bay, offshore of the greater Los Angeles metropolitan area, is a critical resource in terms of fisheries, habitat, and recreation. Many threatened and endangered species, such as the brown pelican and least tern make their homes in the watershed. The bay and beaches also serve as primary recreation resources, supporting a $10 billion tourism and recreation industry. Yet, urbanization and industrialization of the region have stressed the bay's resources and polluted the sediment.

Photo of Santa Monica Bay courtesy of Kevin Snavely, City of Los Angeles, Bureau of Sanitation.

The history of Los Angeles is a relatively short one marked by periods of rapid growth. Over the last 100 years, the population has grown from 100,000 to over 10 million residents in the greater Los Angeles metropolitan area, making it the second largest metropolitan area in the United States behind New York. The demands for waste disposal and the pollution associated with rapid population growth have had a tremendous impact on the bay and its resources. While improvements in sewage treatment, such as updating to secondary treatment, have made a noticeable difference in the health of the bay, it is still in jeopardy. Today, the greatest overall threat to the bay is stormwater run-off.

Sign at the mouth of Malibu Creek warning of polluted stormwater.

Storm drain outfalls empty into various waters sources, which all feed into the bays and oceans. As a result, residual oil and gas on the streets, pesticides, fertilizers, pet waste, and litter all enter Santa Monica Bay. While these individual sources may seem small, the cummulative impact of the increasing population poses a severe threat to water quality. Efforts by the City of Los Angeles Bureau of Sanitation to divert flows from selected storm drains during dry weather to the Hyperion Treatment facility have resulted in full secondary treatment for a portion of the stormwater. Unfortunately, there is still a large amount of untreated stormwater material entering the bay.

Pollutants that enter the bay, whether through sewage disposal or stormwater run-off, bind with the sediment in the bay and are transported or buried with it. Recent studies show that over 90% of the area in the bay has contaminants at levels at which biological effects begin to occur. While pollution in Santa Monica Bay is heavily monitored and researched, most of those studies focus on present conditions. To accurately assess the overall state of the bay and to properly manage its future, it is important to understand historical and present conditions.

Because pollutants bind with sediment, the sediment carries a record of current and historical contaminants. Identifying sediment transport pathways allows for predicting the fate of contaminants, and thus predicting the future health of the bay. To address these issues, the US Geological Survey's Coastal and Marine Group, Southern California Water Research Project (SCCWRP) and the City of Los Angeles, Bureau of Sanitation are studying the sediment of Santa Monica Bay in an effort to document the historical contaminants in the bay, to determine the future of the bay and its resources, and to provide managers with valuable information for environmental decision making.

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