KCBS_740 SAN FRANCISCO (KCBS) — The natural landscape of the Wild West is disappearing.

A new report finds that from 2001 to 2011, an area totaling over 4,300-square-miles, or 15 times the size of San Jose, Oakland and San Francisco combined, was modified by development in the 11 Western states, with California losing the most natural land.

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Conservation Science Partners found that every few minutes, those 11 states lose a football field-sized chunk of natural land to development.

“Each year, we’re building out about a Los Angeles-sized area of infrastructure across the west,” Matt Lee-Ashley, Senior Fellow and Director of Public Lands for the Center for American Progress told KCBS.

The study looked at Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming.

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Nearly a quarter of California’s land is protected from development, but it lost over 700-square miles alone over the period studied.  That development puts added stress on wildlife.

Read the ‘Disappearing West’ study here.

“You have roads and transmission lines that carve up wild areas that into smaller and smaller areas, and that makes it harder for wildlife to migrate across large landscapes,” Lee-Ashley said.

In the Bay Area, Solano County lost the most open space to development, totaling 11,000 acres.

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“If you were to think about a bear wandering on a random path through the west right now it would only be about three and a half miles for him (to see) significant human development on average,” Lee-Ashley said.