Three conservation groups are suing the Central Valley Regional Water Board, saying the agency trusted to protect California's drinking water is letting loggers pollute it.

But loggers are challenging the board's decisions, too complaining that the rules are too strict.

California's regional water board can impose restrictions and requirements on a business or industry that releases waste into the state's water supply. But if board members rule the released waste won't hurt the public, the water board can waive the rules.

The two challenges stem from a January water board decision on logging waivers that exempt timber harvest plans from parts of California's Clean Water Act. Originally given in 1982, the waivers expired Jan. 1 of this year.

Central Valley water board members who represent the San Joaquin Valley, Sacramento Valley and Western Sierra renewed the waivers, but attached stricter environmental regulations to them. Those conditions prompted the California Forestry Association to appeal to the state Water Quality Control Board on the grounds that regional officials were too harsh on logging companies.

But conservation groups DeltaKeeper, Environmental Protection Information Center and Sierra Club sued the Central Valley Regional Water Board in Alameda County Superior Court, upset that board members renewed waivers at all.

No hearing dates have been set.

"The industry sued us, the environmental groups sued us, so we're probably about in the right place," said Jim Pedri, the Central Valley board's assistant executive officer.

Representatives of the two groups suing the board disagree.

Environmentalists say logging dumps soil and plants into streams, in turn increasing water temperature and erosion. The groups also allege that herbicides, pesticides and oil used by loggers and their machines contaminate the water.

"The protection of these rivers and streams is of utmost importance to millions of Californians, especially those who drink water from these sources," said Cynthia Elkins, programs director for EPIC. "Unfortunately, the water board seems more interested in protecting logging companies rather than its mandate to protect and restore water quality."