The Environmental Quality Element presents a comprehensive package of policies and programs that protect Marin County's natural resources. These resources include land, water, and air, as well as aesthetics and wildlife habitat. The Environmental Quality Element describes the County's targets for open space preservation and sets forth policies for the preservation of mineral resources. This Element satisfies State requirements for conservation and open space elements of the Countywide Plan.

For purposes of environmental planning, the county is divided into three north/south corridors. Each of the three environmental zones has a unique set of land use, development, and open space issues, all which are addressed in this element. The environmental corridors are designated as follows:

• The City-Centered Corridor along Highway 101 and adjacent to the Bay is designated for concentrated urban development and for protection of designated environmental resources.
• The Inland Rural Corridor in the central and northwestern county is designated for agriculture and compatible uses and for preservation of existing small communities; and,
• The Coastal Recreation Corridor, adjacent to the Pacific Ocean, is designated for Federal parklands, recreational uses, agriculture, and the preservation of existing small coastal communities.

B. Resource Conservation Areas

The following conservation areas have been identified for policies and programs:

Policies in this document establish buffer zones called Stream Conservation Areas (SCAs) for the protection of riparian systems, streams, and related habitats. SCAs exist along perennial and intermittent streams, as defined by solid and dashed blue lines on USGS quad maps.

A Stream Conservation Area consists of a watercourse, surrounding banks, and a strip of land extending laterally from the top of both banks. Uses allowable in the Stream Conservation Area include: necessary water supply and flood control projects, improvements to fish and wildlife habitat, grazing, agriculture, maintenance of channels for erosion control, water monitoring installations, and trails. Prohibited uses include, but are not limited to: roads and utility lines (except at crossings), confinement of livestock, dumping, use of motorized vehicles, and new structures.

The Coastal Conservation Zone extends from the Pacific shoreline of Marin County inland, 1,000 yards or more. The Coastal Zone boundary is coterminous with the Coastal Recreation Corridor boundary from approximately Olema north to the Sonoma County line. This element refers to policies and standards in the Local Coastal Plans I and II which have been approved by the California Coastal Commission and County of Marin Board of Supervisors. The Local Coastal Plans detail policies and standards for future land use, development, and activities within the conservation zone.

The Bayfront Conservation Zone includes tidal marshes, seasonal marshes, lagoons, natural wetlands, and low-lying grasslands overlying historic marshlands. Three subzones exist within the Bayfront Conservation Zone: 1) the Tidelands Subzone, areas subject to tidal action; 2) the Diked Bay Marshlands and Agricultural Subzone, former marshlands which have been diked and often filled for agricultural and urban uses; and 3) the Shoreline Subzone, steep shoreline areas between roadways and Tidelands Subzones.

The County has adopted a zoning overlay district in unincorporated bayfront areas, requiring environmental assessment of existing conditions within the Bayfront Conservation Zone prior to preparation of master plans and development plans. Policies in this Plan encourage land uses that enhance wildlife and aquatic habitat, such as agriculture, wastewater reclamation, restoration of lands to tidal status, and flood basin.

In the Diked Bay Subzone, land uses are encouraged which provide or protect wetlands and which do not require diking, filling, or dredging. Other uses may be allowed if they are consistent with zoning designations and impacts are minimized and mitigated. Uses must also conform to applicable Federal and State regulations. Restoration of bay marshlands offers significant potential for habitat value and will be encouraged whenever possible.

Policies in this document preserve the dramatic viewsheds and coastal habitats in the Shoreline Subzone.

Air quality policies follow Federal and State air quality guidelines for carbon monoxide, ozone, nitrogen dioxide, sulfur dioxide, and total suspended particulates for management of locally generated pollutants.

Although the ambient air quality in Marin is high, the County recognizes that Marin benefits from its upwind location relative to prevailing wind conditions in the Bay Area. The County should seek to reduce pollution generated by land uses and transportation. Air pollution has the potential to particularly affect "sensitive receptors" like hospitals and schools and air quality should be considered when locating these types of facilities.

The State Mining and Reclamation Act of 1975 requires that the County adopt policies to protect certain State-designated mineral resource sites from land uses which would preclude or inhibit mineral extraction needed for satisfying market demand on a timely basis. The purpose of the Act is to ensure that construction materials will be available to all areas of the State at a reasonable cost.

Eight mineral resource sites were designated in Marin County, two of which no longer meet minimum threshold requirements and are exempt from application of mineral resource policies. Of the remaining six sites, four are located within incorporated areas. The State has designated one of the resource sites, Ring Mountain, as a scientific resource zone and 300 acres have been preserved as open space. One of the mineral resource sites (near Pt. Reyes) is located in the unincorporated county and subject to the policies in this plan.

The lands in Marin provide habitat for a rich variety of plants and animals. However, several species of plants and animals and some natural communities in Marin County are becoming increasingly rare, due to changes in the landscape caused by human activities. Through the development review process, the County seeks to protect the natural habitat from detrimental human activity.

The built environment policies address aesthetic and environmental issues including, but not limited to: preservation of ridges and upland greenbelts, creekside development, design standards in planned district categories, and guidelines for the design of activity centers, preservation of cultural and archeological resources, and protection and enhancement of view corridors.

Several of these policies have been implemented through zoning and subdivision laws. Review procedures ensure that proposed developments comply with the County's conservation policies.

The County's Open Space program targets land in each of the three environmental corridors to be reserved as permanent public open space for recreational or environmental protection purposes. Targets have actually been exceeded in the Inland Rural and Coastal Recreation Corridors, due to Federal and State parkland purchases and recreational use of lands acquired for watershed. However, only 56% of targeted lands in the City-Centered Corridor have been acquired, including all lands owned by public and quasi-public agencies.

The Open Space Program identifies a number of techniques for achieving the desired targets, such as transfer of development rights; zoning regulation (e.g. low density zoning); and, gift, dedication, or purchase of lands by the Open Space District or other public entity.