Attempting to Get a Handle on Waterborne Pollution

SIMI VALLEY SITS at the head of Ventura County’s 350 square-mile Calleguas Creek watershed. The opposite end of the waterway empties into Mugu Lagoon and the Pacific Ocean (see article on Mugu lagoon).

Concern over exactly what the creek carries to the sea has prompted California state water quality regulators to issue an order for cities and county agencies to identify and map the sources of pollution that end up in the environmentally sensitive lagoon.

In August, 1998, the planned three-year Calleguas Creek Characterization Study, as the monitoring effort is called, began monthly water tests at eighteen points along the creek and the tributaries feeding it. An additional twelve underground sites (aquifers) will also be tested. The various pollutants will be identified to help pinpoint their sources. Agricultural pollutants will be distinguished from urban runoff that contains contaminants such as animal waste and motor oil.

Concern over pesticides stems from their widespread use on farms. DDT—a compound employed worldwide—had also been used extensively by farmers and by the Navy at its Point Mugu base until it was banned in the 1970’s. DDT was linked to the near extinction of the brown pelican and other birds native to the lagoon. (Mugu Lagoon is a stopover for migrating birds as well.) The pesticide has a life of 50 to 100 years before it breaks down. Scientists have found DDT at depths of two feet in Mugu Lagoon sediments and expect that it may be present as deep as 30 feet.

In this muddy containment, the DDT has less impact on the food chain and as a result brown pelican numbers are growing. Yet, mussels, clams and certain fish contain elevated DDT levels and are unsafe to eat. The concern is heightened because of the ocean erosion which chews away at the sediment releasing the pesticide and other pollutants.

The creek and lagoon contain more than a dozen pesticides, herbicides and chemicals that present risks to humans and the environment. Because of cleanup efforts quantities of three toxic metals and PCBs have been reduced in the lagoon to levels thought to be safe. However, any comprehensive plan to eliminate or mitigate the pollution is years away. The problem is difficult because no one can be sure what actions might correct the problem without causing an even larger difficulty.

The Characterization Study, which is a key part of the larger Calleguas Creek Watershed Management Plan, takes the early, necessary, step of identifying the scope and complexity of the pollution as well as its various sources. In the meantime, the U. S. Navy—custodian of the lagoon—will continue to monitor the populations of threatened and endangered species.

Various federal programs—now in place and under development—provide monetary incentives for habitat development on agricultural lands. Use of cover crops, buffer strip plantings and other techniques that will reduce farm runoff—and the amount of pollutants entering the creek—are part of the answer. Some of these programs face funding problems and tend to lose their attractiveness to farmers because of complicated and competitive application processes.

The state Coastal Conservancy has provided $305,600 for bank stabilization along a tributary of Calleguas Creek. The money is related to a $52 million federal plan to reduce by two-thirds the sediment entering the creek. Revegetation, rather than concrete, will be used in the erosion control effort that will receive additional grants and contributions from landowners.

While the pollution in Mugu Lagoon is studied, natural forces continue to work on the salt marsh—to what end, man can only guess.

See also Mugu Lagoon: A Study in Erosion.

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