The Marin Municipal Water District (MMWD) is the government agency that provides drinking water to southern and central Marin County, California. Chartered in 1912, it became California’s first municipal water district. The District’s seven reservoirs in Marin County provide about 75% of the water it uses: Alpine Lake with Cataract Falls, Bon Tempe Lake, Kent Lake, Lake Lagunitas, Nicasio Reservoir, Phoenix Lake, and Soulajule Reservoir.

If you’re looking for serious trail options with your dog, MMWD manages 130 miles of trails and unpaved roads across these watersheds. Many routes connect with adjacent national and state parks and county open space district lands, so you can string together longer days if you want. The terrain varies from easy lakeside walks to more challenging ridge hikes, depending which watershed you explore.

Dogs are allowed throughout MMWD lands, but they must be leashed at all times and under your direct control. This is nonnegotiable—the agency is protecting sensitive habitat and species listed as endangered, and off-leash dogs have a real history of causing problems here. They’ve intimidated wildlife, endangered newborn deer, and disrupted aquatic ecosystems. A leash also keeps your dog safe from the wildlife, particularly on the Mt. Tamalpais Watershed where the California Department of Fish and Wildlife manages the Mt. Tamalpais State Game Refuge alongside MMWD.

Most of these lands are working watersheds, so water quality and wildlife protection come first. That said, there’s legitimate hiking and walking here—you’re not just trudging around a filtered water system. The reservoirs themselves are scenic, the vegetation changes with elevation, and you’ll likely see deer, coyotes, and various birds depending on the season and time of day. Stick to marked trails, bring water for both of you, and plan for the weather, which can shift quickly on Tamalpais.