Bowing to public calls for a robust environmental review, the Monterey County Water Resource Agency canceled plans to disperse silver iodide by plane off the Big Sur coast in an effort to increase precipitation this rain season.

“We’re moving forward with the environmental document, but we’re not going at as fast a pace,” says Robert Johnson, MCWRA’s chief of water resources planning. “We’ll see where we’re at for next winter.”

Cloud seeding involves the aerial release of silver iodide, which has a molecular structure similar to ice. The particles concentrate moisture and increase rainfall, which officials estimate could boost stores in the San Antonio and Lake Nacimiento reservoirs by more than 10 percent. At about $250,000, the project is considered cheap for the quantity of additional water it could produce in the drought-stricken Central Coast.

In mid-October, the MCWRA released an initial study and draft negative declaration on the “weather modification” project, which if approved, would allow cloud seeding to proceed without a full review under the California Environmental Quality Act. The move ticked off eco-watchdogs who want an environmental impact report and Big Sur locals who feel left out of the decision-making process.

The agency received a half-dozen comments raising concerns about the project, including two from lawyers. Several Big Sur locals worried that heavier rain could trigger landslides in areas made less stable by the 2008 fires, particularly in an El Niño year. Others raised questions about potential health impacts on people and wildlife, among other issues.

Only one comment, a letter from the local Air Pollution Control Agency, raised no objections.

The topic was not so controversial in years past. Johnson says the agency adopted negative declarations for cloud seeding done in 1990-1995 and 2004. “This year we had a lot more comments than expected, so we had to make a more robust documents,” he says.

The MCWRA planning committee took the issue off its Dec. 17 agenda, giving staff time to complete a more in-depth environmental review.