The California Coastal Commission is scheduled to consider Thursday a request to revoke a permit for a desalination plant in Carlsbad. It's the latest effort by environmental groups to block the plant, which they say will hurt coastal wildlife.

Poseidon Resources Corp. which recently began preparing the site next to the Encina Power Station for construction, said the request is groundless.

If the request is granted, Poseidon would have to stop construction and reapply for a new permit. The plant will have a capacity of making 50 million gallons of fresh water a day, enough for 9 percent of the county's needs.

Marco Gonzalez, an attorney for the Coastal Environmental Rights foundation, said Poseidon Resources, the plant's builder, intentionally withheld information from the commission about how the plant would "impinge," or trap fish against its intake.

"We've asked the Coastal Commission to reopen their hearing, and do a full assessment of all the changed circumstances that have occurred since the Coastal Commission heard their permit in November of 2007," Gonzalez said.

Scott Maloni, a Poseidon vice president, said the request is "patently frivolous and without merit."

In a report, commission staff members wrote that the grounds for revoking a permit are "narrow," and the request doesn't meet the criteria.

"The rules of revocation do not allow the commission to have second thoughts on a previously issued permit based on information that comes into existence after the granting of a permit, no matter how compelling that information might be," the report stated. "The grounds for revocation are confined to information in existence at the time of the commission’s action."

Call staff writer Bradley J. Fikes at 760-739-6641. Read his blogs at bizblogs.nctimes.com.