A state motorcycle park will stay open while it measures pollution into the muddy Corral Hollow Creek, an appellate judge ruled Tuesday in a move lauded by off-road enthusiasts and shrugged off by lawyers seeking to close the trails.

Carnegie State Vehicular Recreation Area had been under threat of shutting down after a legal battle with environmental groups, whose lawyer said the park has a lot of work to do to comply with water laws.

Carnegie spans 1,500 acres of hills and canyons southwest of Tracy, and sits on the seasonal creek, which flows during heavy rain into farm fields in the valley.

The state said the park is working on a plan to keep riders out of the creek to control sediment and erosion. The Central Valley Regional Water Board in January asked the park for more information in its incomplete pollution report, which acknowledged high levels of copper, aluminum and other metals in the stream.

Last year, environmental groups sued the park for muddying the creek with sediment and metal, and for doing it without telling the water board. An Alameda County judge ruled the park shut down, but it never did — a court order delayed the closing in December, after hundreds rallied to keep park open.

The San Francisco judge overturned the decision, stating the California Sportfishing Protection Alliance and the Public Employees for Environmental Responsibility should’ve contacted state and regional water boards before bringing the matter to court.

Michael Lozeau, an attorney for the sport fishing group, said he didn’t consult the state water board since it’s the agency’s duty to get permitted. But he said he wasn’t surprised the “chronically understaffed” water board hadn’t sought one.

“They would probably have in their heads the assumption their sister agency might be complying with the law,” he said.

State parks district superintendant Bob Williamson said Carnegie had never before sought a permit to let motorcycles ride through the creek because the state had never asked.

Dave Clegern, spokesman for state water board, said the regional board relies on complaints to do inspections in a region that spans from Yuba City to San Jose.

The Clean Water Act and the Porter-Cologne Water Quality Control Act require that companies and agencies report the affect of their actions on groundwater.

One off-road vehicle activist, Bruce Brazil, said he’s ridden at Carnegie since the 1970s, when it was still private property.

He said the fuel left by motorcycles and the mud that runs into the creek bed should be of little concern because it mostly runs dry, and he blamed the Public Employees for Environmental Responsibility for waging all sort of attacks on trails across the state.

“They came in there looking for something to shut it down,” he said.

Lozeau said he’s not finished with the case, despite what he called the “procedural hurdle” of the overturned closure.

He said state officials should put in the effort to get things right by closing trails when it rains and “vigilantly” keeping riders out of the creek.

“The rangers just stand by watching people driving into the creek,” he said. “Every time it rains, the creek flows into the park clear and comes out of it looking like coffee. Obviously what’s happening is clearly a violation of the water law.”

Contact Tracy Press reporter Cassie Tomlin at 830-4225 or ctomlin@tracypress.com.