The Midpeninsula Regional Open Space District (MROSD) is a special-purpose district that manages over 50,000 acres (200 km²) of open space in 25 preserves in the San Francisco Bay Area. It includes parts of Santa Clara, San Mateo and Santa Cruz Counties. The District was created by voter initiative in 1972. The mission of the District is "to acquire and preserve a continuous greenbelt of protected open space lands for public use and enjoyment." It is a member of the Bay Area Open Space Council.
The District's tax and voter base consists of about 550 mi² (1,400 km²) and 741,000 people, mostly in Santa Clara and San Mateo counties. District revenues for fiscal year 2008-2009 were 38.0 million, with 26.4 million coming directly from a portion of property taxes. It also occasionally receives state and federal grants, as well as private donations.
Most of the preserves are open to recreation. Popular activities are hiking, cycling, and horseback riding. Camping is generally prohibited, though the Monte Bello Open Space Preserve does have a backpacking camp available by permit only. Of the 26 preserves, 24 are fully open to the public: Mills Creek Open Space Preserve and Tunitas Creek Open Space Preserve are not open; the Bear Creek Redwoods Open Space Preserve and La Honda Creek Open Space Preserve require a permit for use, and portions of Sierra Azul Open Space Preserve are closed to the public due to toxic contamination at the summit of Mount Umunhum.
In total, the district has 226 mi. (364 km) of hiking trails, of which 150 mi. (241 km) is open to bicycles, 182 mi. (293 km) to equestrians, and 63 mi. (101 km) to leashed dogs. Preserves are relatively undeveloped, with most having only a parking area, trail signs, and possibly an outhouse. All preserves are open from dawn to one-half hour after sunset.
The following open space preserves are managed by MROSD: