State water regulators have fined a pair of Mendocino County landowners $30,000 for an alleged illegal reservoir that diverted water from a stream west of Ukiah.

Since at least 2007, Steven Rector and Anne Carole Frocteau have been diverting an unnamed tributary of the Navarro River on their 67-acre Comptche-Ukiah Road property, regulators with the State Water Resources Control Board said.

"They illegally constructed a dam in a stream," said Stormer Feiler, an environmental scientist with the water board's North Coast region. "It was poorly constructed and appeared to be something that could fail."

The agency announced a settlement with the landowners Tuesday.

The .45-acre reservoir created by the earthen dam was used for gardening and marijuana cultivation, according to Feiler.

Rector, 51, whose first name is sometimes listed as Stephen, is currently on trial in federal court in Kansas for possession and conspiracy to distribute more than a ton of marijuana. He was arrested last year along with 24 others after a federal investigation uncovered a major California-Kansas drug ring.

Frocteau, whose last name is also publicly listed as Foucteau, has not been charged in any criminal case. Anne Carole Foucteau-Rector is identified online as a Fort Bragg chiropractor. A message left with her office was not returned Wednesday.

Joshua Bloom, Rector's lawyer for the water board case, confirmed the settlement and had no further comment.

The maximum penalty that could have been imposed by the state was $125,530, according to the settlement agreement.

Feiler said the landowners are in the process of obtaining a permit to leave the dam in place. If denied, they would have to remove the dam and do environmental restoration work on the stream.

The state enforcement is part of a larger crackdown on unauthorized stream diversions in Wine Country and along the North Coast. Federal officials say diversions for agriculture are a primary cause of mass strandings and fish kills for federally protected salmon and steelhead runs.

The general crackdown on unauthorized water diversions began in April 2010, with notifications to property owners that all unreported unpermitted uses dating from 2009 forward would be subject to monetary penalties.