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Institute suggests dikes, wetlands be used to preserve Salton Sea habitat

December 01, 2001|By RUDY YNIGUEZ, Staff Writer

OAKLAND — A think tank here is proposing to preserve and enhance the environmental habitat of the Salton Sea through the use of dikes, wetlands and management practices to reduce nutrient loads from agricultural, municipal and industrial sources.

The Pacific Institute for Studies in Development, Environment and Security's proposal would satisfy the dual objectives of addressing the ecological health of the Salton Sea while facilitating the pending transfer of water between the Imperial Irrigation District and the San Diego County Water Authority.

Under the proposal — due to be presented at the Salton Sea Authority Board of Directors meeting Wednesday — there would be an impoundment dike at each end of the sea.

Michael Cohen, Pacific Institute senior research associate, said the idea for using dikes to help save the sea is an old one. The current proposal stems from comments made by the institute on the draft environmental impact report/environmental impact statement on restoring the sea, released in January 2000.


Cohen said the proposal is a reasonable and sustainable plan that primarily can sustain the sea's habitat while retaining the sea as a key part of the Pacific Flyway. In addition, he said the area's economy could improve as well as the area's recreational value.

The study has been presented to others in the environmental community.

Tom Graff, senior attorney with the Oakland-based Environmental Defense Fund, said the plan definitely should be one of the alternatives to review in deciding the environmental future of the sea.

"Yes, we are supportive of it being studied very carefully," he said.

Graff said he would like to know what scientists think of the plan, including those who work for the Salton Sea Authority.

Salton Sea Authority Executive Director Tom Kirk has seen the plan but could not be reached for comment.

The cost of constructing the dikes depends on their length. Their operation and maintenance will be influenced by the many earthquake faults in the area. The cost for the dikes is based on estimates found in the draft EIR/EIS. Costs range from a low of $42 million for a seven-mile dike at the north end of the sea, to as much as $340 million for a 38-mile dike at the south end.

Cohen said the cost could be borne by those involved in the transfer of water out of the area, in addition to state and federal governments.

"People benefiting from the transfer ought to pay something," Cohen said, adding that perhaps a yearly environmental premium from the water transfer could be paid toward the sea.

Cohen said the dikes would not have the high long-term costs associated with solar evaporation ponds.

The dikes would follow certain elevation contours. The northern dike would follow the minus-240 feet elevation level of the sea. The dike at the south end would be at the minus-240 feet elevation or at the minus-245 feet elevation; it is still undecided. Also undecided is the length of the southern dike.

In the north, the dike would impound the Whitewater River, while in the south the dike would impound the Alamo River, New River, San Felipe Creek and agricultural drains, according to the proposal. The eastern extent of the southern dike would join the shoreline either near Bombay Beach — protecting Mullet Island as a rookery — or further south, near Wister. The western end of the southern dike could be configured to exclude San Felipe Creek, limiting the predation of desert pupfish that use that habitat.

If damaged by an earthquake, Cohen said the dikes — with proposed widths of 20 feet — could be filled in. Also, that the proposed width of the dikes would tend to minimize their damage. Any fish that escaped to the larger body of water due to damage would eventually be replaced. Cohen said that despite the high occurrence of earthquakes in the area, the proposal is the most pragmatic approach.

Selenium could prove a problem, however. The proposal states that any selenium in the sea's sediment could re-enter the food chain during construction of the dikes.

"It's not exactly clear what's going on with selenium," Cohen said when asked if he was aware that core samples show selenium has not been found where the Alamo and New rivers enter the sea.

Meanwhile, under the plan, the main body of the sea would be allowed to go hyper-saline at a rate faster than would occur without the dikes. The result would be the loss of fish in that area, though invertebrates such as brine shrimp and brine flies would thrive, providing a food source for many species of waterbirds, the proposal says.

Under the proposal, the main body of the sea would shrink at a rate that would depend on inflows, Cohen said. If fallowing is used as a means of conserving water in the Imperial Valley, then the sea would shrink at a slower rate than with other measures.

The Salton Sea suffers from an excess of salinity and an over-productive fishery that can rob organisms of oxygen.

Cohen will make his presentation before the Salton Sea Authority Board of Directors on Wednesday. The board meets at 2 p.m. in the IID boardroom in La Quinta, 81-600 Ave. 58.

>> Staff Writer Rudy Yniguez can be reached at 337-3440.

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