California Land Use Plans and Potential Resource Conflicts

Bob Johnston

Kaoru Dobeta

Shengyi Gao

Dept. of Environmental Science and Policy University of California, Davis

Sept. 15, 2004

Purpose

The purpose of these two interactive map projects is to demonstrate that the widespread zoning for rural residential land uses in California counties results in many apparent conflicts with natural resources

The maps will draw faster if you zoom to a county or a group of counties. Also, the maps are easier to read if you zoom to one county.

There are two set of interactive maps. Both contain a General Plan layer that was created from California city and county general plans, categorized into our ten urban land use types. For locally designated open space and agricultural lands, we inferred the Residential Low Density and Residential Very Low Density zoning categories from Census population density at the block level for the year 2000. For a description of the methods we used for this classification, see: http://gis.ca.gov/catalog/BrowseRecord.epl?id=21453 Go to the View Supplemental Information button. Low Density is 2- to 20-acre parcels, while Very Low Density is 20- to 160-acre parcels. We defined these two categories because even quite low densities can affect medium-sized and large mammals and also prevent arial spraying in agriculture.

The first interactive map, General Plan Conflicts 1, gives several natural resources layers and places a transparent version of our Local General Plan layer on top.Starting at the bottom of the theme bar, we have FireThreatVeryHigh and FireThreatExtreme, both of which come from the St. Dept. of Forestry web site. We use their definitions of extreme and very high wildfire Threats to People. You can see that many counties have designated large areas of very high and extreme fire hazard for residential development. The next layer is Important Vegetation, in which we selected vegetation types from the St. Dept. of Forestry, FRAP web site, Multi-Source Vegetation Map, which used the California Wildlife Habitat Relationship vegetation types. With a biologist in our dept. we selected vegetation types that are rare in California. This is a rough representation, for display purposes, as there are debates about this issue. Habitat linkages come from the California Wilderness Coalitions linkages map from 2003 The Farmlands layer includes the St. Dept. of Conservation types prime, statewide, and unique in their 2000 layer. Polluted surface waters, rivers, and coastal waters come from the St. Water Resources Control Bd. Sec. 303 waters maps. Existing Urban comes from the St. Farmlands layer for 1998. This map clearly shows considerable conflicts between rural residential growth and important farmlands, fire threats, and important habitat cores and linkages. In addition, we can see large areas where development is allowed near to polluted waters and could contribute to further pollution unless runoff controls are enacted.

The second map set, General Plan Conflicts 2, gives similar data, with our local general plan layer on the bottom in an opaque layer. The local land use plans are as we described above. The Urban2020 and Urban2050 layers are by John Landis at UC Berkeley, from the St. Dept. of Housing and Community Development web site. We think that future growth will be much more spread out, as indicated by our general plan layer, but these projections are the only official State ones. Existing Urban is as defined above. Vernal Pools and the Natural Diversity Database layers are from the St. Dept. of Fish and Game web site. Habitat Linkages are as defined above. From this map, we can see conflicts between allowable future growth and vernal pools, a very rare and important habitat type in this state. We can also see widespread conflicts with the Habitat Linkages, which are critical connectors for larger habitat core areas.

The third map set, General Plan Conflicts 3, shows Federal T&E species and local general plans. The best approach is to make one species at a time the Active Layer and then choose the Zoom to Active Layer button. This will then make the map cover only that listed species' habitat areas. If you turn on the General Plans layer, you can then see the conflicts with local plans.

We hope that these maps will encourage the State resources agencies, private groups, and other researchers to describe these conflicts in more detail and to take action to reduce the losses of these natural resources.