[1][2] The preserve is approximately 18 miles (29 km) east of the town of Marysville and Beale Air Force Base in the eastern Sacramento Valley.

It is notable for many species of native birds and wildflowers, including the California endemic Yellow mariposa lily (Calochortus luteus).

[3] The geology of the Spenceville area is part of the Smartville Block formed during the Middle Jurassic epoch 200 million years ago.

The Smartville Block is a part of the California Mother Lode for gold, and consequently Spenceville has had its share of mining activity.

[4] The area was originally home to the Maidu and Nisenan Native Americans and evidence of their grinding holes and lodge pits still exist.