Nature plays major role in cleaning polluted waters

June 07, 2001|By KEVIN MARTY, Staff photographer

Evaporation of water from the Salton Sea reaches 4 billion gallons each year.

Yet the surface elevation of the sea remains about 232 feet below sea level. That means 4 billion gallons of water must be added each year.

The New and Alamo rivers and irrigation runoff from agricultural fields are a large contributor to this balancing act.

The two rivers are considered by some as the most polluted waters in the country. They flow north across the Imperial Valley and pick up pollutants from a variety of sources along the way, including agricultural fields, although much of the pollution in the New River comes from Mexico, where the river starts.

Marie Barrett of El Centro is part of a program to address the pollution. She coordinates the New River Wetlands Project, designed to improve water quality before waters enter the Salton Sea.


"It's all natural. We don't introduce any chemicals or anything. I think we have lost approximately 90 percent of our wetlands in California. This is a good opportunity to reestablish some wetlands," Barrett said.

Polluted water enters the wetlands at one end, takes 20 days to reach the other end, and exits unpolluted. This is the project in its simplest form. The wetlands are a chain of basins filled with earthen barriers and plants.

The project began during spring of last year, with the establishment of two wetlands along the New River. Water is piped in from the Rice Drain west of Imperial at one site, while the other site near Brawley receives water directly from the New River.

As water enters the first basin at each site it drops sediment and continues to the next basin. The water flows between basins by pipe connected to gated cement structures. The gated structures control water flow.

Within the basins, bulrush and sedge plants impede the flow and establish a plant community for microorganisms to flourish and help break down pollutants. Once treated, the water is diverted back into the New River.

Barrett has proof the setup works. The first monitoring results of this project show at the wetlands near Imperial, a 68-acre site, total suspended solids were down about 95 percent during February and March of this year. Dissolved oxygen increased about 56 percent. Increasing dissolved oxygen is correlative to decreasing pollutants.

Similarly, at the Brawley wetlands, a 7-acre site, total suspended solids decreased about 93 percent during February and March, while dissolved oxygen increased about 83 percent.

Nutrient (e.g., nitrogen and phosphates) levels have decreased at each site. This is expected to continue as plants mature and microorganisms get established.

"It's a wonderful program with great concepts. This is just the start. As soon as we are sure it will work, then we will take the next step, which is inventory of other areas for wetland sites. We hope to get funding to build more wetlands along the New and Alamo rivers," Barrett said.

Following establishment of the wetlands, a variety of birds and other wildlife have moved in.

"The public is welcome to come down and use these areas anytime. We already work with schools, especially ROP and their outdoor program. It's a great learning opportunity," Barrett said.

Messages for Staff Photographer may be left at 337-3416.

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