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California Summary

Below you will find county-by-county maps and tables that illustrate the data in this study.

Click on chart for a larger version below.

Our research found that:

  • Of the 11 western states, California has the largest area of forested land where homes have already been built next to public lands, and is second only to Oregon in the area of undeveloped, forested private land bordering fire-prone public lands.
  • California has over 5,000 square miles of forested private land bordering public land, of which 83 percent has not yet been developed.
  • Even though California has the most densely developed wildland urban interface in the West, lot sizes are still larger than those on other private lands.
  • Housing in California's wildland urban interface consumes 2.3 acres per person, compared to the 0.5 acres per person average on other private lands in the West.
  • California has 341,175 residences in its wildland urban interface, of which 19 percent are seasonal homes or cabins.
  • California ranks first among western states in the number of homes built in forested areas next to public wildlands, and ninth in the percentage of those homes that are only seasonally occupied.

Several counties in northern and central California rank high in terms of existing risk of wildfire (number of square miles of the wildland urban interface with homes now). El Dorado County has 20,333 homes spread across 70 square miles of wildland urban interface. In the Southern Cascade range of northern California, Trinity County has 5,331 homes spread throughout 64 square miles of land adjacent to forested public wildlands. Also in the southern Cascades, Siskiyou and Shasta Counties rank quite high in terms of potential future risk (number of square miles of wildland interface that remains undeveloped). Combined, these three neighboring counties in northern California contain 1,253 square miles of private land next to fire-prone wildlands. If homes were to be built in these high-risk places, the cost to defend them against wildfire would be substantial.

Existing Risk Map - Click to Zoom
Yellow areas on the map illustrate existing development in fire-prone areas (forested areas adjacent public lands that have been developed); all other development is shown in red; public lands are shown in green.

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California Summary Statistics
West-Wide 3,290.0 20,350.1 14.0% 915,071 21.0%
California 871.8 4,257.0 17.0% 341,175 19.0%

Top 10 Counties in California Ranked by Existing Risk

Counties are ranked by the number of square miles of developed land in the wildland interface
El Dorado County California 69.8 164.3 30.0% 20,233 24.0%
Trinity County California 64.1 310.9 17.0% 5,331 25.0%
Nevada County California 46.5 132.9 26.0% 17,173 21.0%
San Bernardino County California 41.2 137.9 23.0% 29,643 45.0%
Tuolumne County California 40.4 92.8 30.0% 10,807 35.0%
Calaveras County California 40.0 89.3 31.0% 8,672 40.0%
Plumas County California 37.8 237.1 14.0% 5,788 25.0%
Placer County California 37.1 154.1 19.0% 15,787 39.0%
Siskiyou County California 34.6 528.4 6.0% 3,613 16.0%
Humboldt County California 33.3 210.0 14.0% 7,578 12.0%

Top 10 Counties in California Ranked by Potential Risk

Counties are ranked by the number of square miles of undeveloped land in the wildland interface.
Siskiyou County California 34.6 528.4 6.0% 3,613 16.0%
Shasta County California 32.3 413.4 7.0% 6,289 10.0%
Trinity County California 64.1 310.9 17.0% 5,331 25.0%
Plumas County California 37.8 237.1 14.0% 5,788 25.0%
Lassen County California 3.8 222.7 2.0% 699 13.0%
Mendocino County California 23.7 216.7 10.0% 5,171 13.0%
Humboldt County California 33.3 210.0 14.0% 7,578 12.0%
El Dorado County California 69.8 164.3 30.0% 20,233 24.0%
Tehama County California 3.3 157.0 2.0% 547 64.0%
Placer County California 37.1 154.1 19.0% 15,787 39.0%

Click on column headers to see all data in the West sorted by that column.

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Headwaters Economics
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