A proposal to enlarge the Nicasio Reservoir has collapsed after months of study, planning and heated community debate—and after residents unearthed forgotten records showing the district had proposed, and abandoned, the same idea more than 40 years ago.
Marin Water, which spent nearly a year pursuing a plan to raise the spillway, announced last week that it would abandon the project, citing runaway costs and limited benefits.
What began as a $10 million to…