Marin Water is studying whether it can release less water from its reservoirs into Lagunitas Creek without harming aquatic species, allowing the district to hold onto more water this winter amid a historic drought. 

The flow reductions would occur from November to March, when the changes could affect spawning and the rearing of fish eggs. Hydrologists chose four stretches of the creek that are typical habitat and will complete a detailed topographic survey there, then…