Concerns about increasing the capacity of a reservoir are seeping from Nicasio to Point Reyes Station like a slow drip through a leaky dam.

Raising the Nicasio Reservoir spillway is one of several short-term steps that Marin’s municipal water district is considering to increase its storage capacity and enhance its ability to endure future droughts. 

The plan calls for installing a 280-foot-long, 4.4-foot-high inflatable rubber gate spanning the top of the spillway. The gate…