Despite blankets of snow and rain that have covered California this winter, the state’s top water cops voted Wednesday to maintain emergency drought rules that have been in place in one form or another during the past 19 months. Regional water managers, including those in San Diego County, traveled to Sacramento to plead with the State Water Resources Control Board to end the emergency regulations. They repeatedly told the board that not doing so would erode credibility with residents and make it harder to convince people to adopt strict conservation efforts in the future.