Lagunitas Creek

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Coordinates: 38°4′48″N 122°49′37″W / 38.08, -122.82694

Lagunitas Creek
stream
Name origin: Spanish

Country	United States
State	California
Region	Marin County


Source	Mount Tamalpais
- coordinates	37°56′51″N 122°35′50″W / 37.9475, -122.59722 ^[1]
Mouth	Tomales Bay
- elevation	0 ft (0 m)
- coordinates	38°4′48″N 122°49′37″W / 38.08, -122.82694 ^[1]

Length	20 mi (32 km) ^[1]
Basin	103 sq mi (267 km²)

Lagunitas Creek is a stream in Marin County, California and is a major supply of drinking water to the area. The 20-mile (32 km) long^[1] creek's headwaters are in the Coast Range and it flows into the Pacific Ocean, draining 103 square miles (267 square kilometers).

The creek's source is the northern slope of Mount Tamalpais, a few miles (~6-8 km) east of Bolinas Lagoon. The creek begins as three forks, the East Fork, Middle Fork and West Fork. After about a mile (1,600 m), they all flow into Lake Lagunitas, which drains into Bon Tempe Lake, which drains into Alpine Lake. Downstream of Alpine Lake, the creek flows roughly northwest until it reaches Kent Lake. Just downstream of Kent Lake, San Geronimo Creek joins the creek. Lagunitas continues northwest and is joined by its largest tributary, Nicasio Creek, which flows from Nicasio Reservoir, another water storage reservoir. Shortly after this confluence, Lagunitas turns westward and flows through the town of Point Reyes Station. On the west side of the town, the creek is joined by Olema Creek and turns northward, emptying into the wetlands at the south end of Tomales Bay.

Each of the reservoirs in the watershed has a dam and the biggest problem in the watershed is their blocking of the streams, which prevents fish migration and dewaters the streambed. Roy's Dam on San Geronimo Creek was built in the 1920s to supply water to a ranch. It was an obstacle for coho salmon and steelhead trying access to the habitat upstream of the dam for spawning. It was decided to lower the dam instead of completely removing it because of the large amount of sediment that had accumulated behind the dam. Erosion is also a significant problem in the watershed.