Lack of Rain, Controls Cut DDT Level in Newport Bay

Levels of the pesticide DDT declined in Newport Bay last year, thanks to scant rainfall and erosion control precautions taken in agricultural fields and along storm channels, state Water Resources Control Board tests showed.

While the levels of DDT and PCBs in in the bay remain high compared to the rest of the state, the declining numbers represent “relatively upbeat news,” James R. Bennett, executive officer of the Santa Ana regional board, said Monday. “In the last couple of years, it had been worsening and worsening. Now we’re seeing that our actions have helped bring about some results.”

At the same time, however, traces of chlordane found in Huntington Harbour were the highest in the state, according to a summary of the state tests prepared by the regional board. Chlordane is an insecticide now used exclusively for termite control.

Mussel Watch Program

The information was gleaned from the State Mussel Watch, a biological-monitoring program which measures pesticides and other chemicals in mussels placed at more than 100 stations in key coastal and bay areas throughout California.

While mussels in two Newport Bay locations had the highest levels of DDT in the state in 1983-84, data from the 1985-86 Mussel Watch showed the highest levels were in San Francisco Bay, Monterey Bay and Point Mugu. Mussels from Newport Bay stations had lower levels, and Anaheim Bay-Huntington Harbour levels were lower than Newport’s, according to the regional board.

Banned in 1972 after it was linked to the decline of the brown pelican and the peregrine falcon, DDT does not dissolve in water and can be retained for years in soil treated with the insecticide.

Less rain during 1985-86 resulted in less soil runoff from the agricultural fields, Bennett said. But he also credited the erosion and silt control measures taken by cities along the storm channels that feed into the bays, and by the Irvine Co., the county’s major agricultural landholder.

Concrete and Channels

Control measures involve irrigation methods and the way storm waters are conveyed down to the storm-control channels, he said.

“There’s been concrete poured, channels lined, grass grown,” Bennett said, adding that the goal of the measures is to “keep dirt and sediment out of Newport Bay.”

Concentrations of PCBs in the Rhine Channel of Lower Newport Bay were slightly lower than last year but were nonetheless among the highest in the state and were several times higher than in Anaheim Bay-Huntington Harbour or elsewhere in Newport Bay, the report said.

An intensive sampling program in the Rhine Channel was begun in June of 1986 to investigate the levels of PCBs and trace metals, and an analysis of the program is expected soon.

Water board officials said the high levels of chlordane found in Huntington Harbour might be from storm drain runoff.

The State Mussel Watch is a reconnaissance program, and the value of information is fully realized only after the data have been consistently tracked for several years, said board spokeswoman Fran Vitulli. She could not say whether the chlordane levels posed any health threat.

“It’s obviously a serious problem, but we’re looking at it,” she said.