CALL IT BEATING government with bureaucracy. A citizen's group trying to stop the poisoning of two north metro lakes has stalled the DNR by forcing the agency to follow its own rules. The DNR wanted to kill off the rough fish in Mud and Howard lakes this fall. They planned to dump in poison when the lakes are mostly dormant, a narrow window between the first hard frost and ice forming on the lakes. The group got a judge to rule the DNR didn't follow its own procedures for allowing public discussion on the plan. So now, the group gets time to circulate a petition to force an environmental-impact study. After the state processes the petition, the public gets 30 days to react, and the DNR gets a month to decide what it will do. By the time the DNR has dotted its i's and crossed its t's, the lake's winter ice could be thawing.