The Marin Municipal Water District took another step this week in pursuit of what the agency says is its largest supply and drought resiliency project in 40 years. The district board voted unanimously on Tuesday to authorize spending $9.7 million to design a pipeline that would tap into an existing aqueduct system to get Sonoma County water to Marin reservoirs. The pipeline project was selected in February as the district’s priority effort to boost supply. If completed, it would be the largest water supply project since Kent Lake was expanded in 1982, according to the district. … Estimated at $167 million, the proposed project would construct a 13-mile, 36-inch pipeline and a pump station to redirect some of that (excess) water into the Nicasio Reservoir for storage. The pipeline could yield 3,800 to 4,750 acre-feet of water a year.