The Virginia State Water Control Board, stung by recent news reports on its policy of moving slowly against municipal pollutors, has decided to release no information from its files or records unless a request is made in writing to the executive secretary.

"It will make it more difficult to obtain news from the Water Control Board," executive secretary Robert V. Davis said. "But we have the responsibility to see that news from this office is accurate."

Davis said the new policy was prompted by "misquotations" in news reports in The Washington Post, although he said he could not recall specifically what they were.

Davis said the Water Control Board at first considered applying the policy only to its former chairman, Fairfax county engineer Noman M. Cole Jr., who has accused the state regulatory agency of caving in to localities whose sewage plants have not met their permit standards.

Davis denied a contention by Cole that the board's members at first limited the new information policy to Cole. Cole, who headed the board in the early 1970s when it took a tough stand against municipal polluters, said he got his information from people who had attended the meeting, held Monday and Tuesday in Virginia Beach.

Commenting on the new board policy, Cole said: "That's the most incredible, dumb thing that's ever been done by a state agency. It practically says they have something to hide."

In the past, various SWCB officials, have released information to reporters during telephone interviews. Here after, any reporter will have to wait days for information that is in records and files.

he most widely publicized case affecting the SWCB involved its decision to overrule staff and take no legal action against the Hopewell, Va., sewage plant for continuous pollution violations since August 1977. Instead, the board gave the city - site of the Kepone pollution diaster, which knocked out the old plant - extensions through December.

Last week the federal Environmental Protection Agency began an investigation of the plant.

James E. Moore, a state assistant attorney general, said the water board's new policy does not violate Virginia's freedom of information act. Moore said the act does not require that public information in records or files be provided over the telephone. Moore said, however, he knew of no other state agency with such a policy.