Lake Lagunitas is a reservoir on Lagunitas Creek in Marin County, California. Lake Lagunitas is one of seven reservoirs providing potable water to the Marin Municipal Water District. It is the oldest and smallest lake in the Mount Tamalpais watershed, with surface area of 22 acres (0.034 square miles or 8.9 hectares). About a mile east to Lake Lagunitas is Phoenix Lake, with surface area of approximately 25 acres. And 0.3 miles to the west of Lake Lagunitas is Bon Tempe Lake, which has an area of (a guess here) 280 acres. Further to the west of Bon Tempe Lake is Alpine Lake with an area of 224 acres.