San Diego NWR Complex
Pacific Southwest Region
vernal pool
San Diego NWR
Vernal Pools

Vernal pools are an extremely scarce wetland habitat type occurring only where certain soil conditions are present. In late summer, fall and early winter, vernal pools appear as dry, dusty indentations mostly devoid of vegetation. 

In late winter, a spectacular transformation occurs.  As these depressions fill with water, high numbers of endangered, rare and sensitive species of plants and animals appear in and around the pools,  many of which can only be found in this system. San Diego Fairy Shrimp and the Western spadefoot toad lie dormant in the pool's dusty crevices until the sound of rain signals breeding time. 

Delicately hued plants also grow during this wet phase, blossom, and change again as the water begins to evaporate in the Spring. As the pools dry, blossoms of every color fill these seemingly insignificant indentations in the landscape. In summer, these temporary wetlands dry out completely until the cycle of life  begins again with the onset of winter rains.

These ancient pools have survived for at least 125,000 years, and perhaps as long as 400,000 years. It was only in the 1980's that their number drastically diminished.  Today 3% the region's vernal pools remain.

Click on a photo below to view a large image
vernal pool in bloom
Vernal Pools In Bloom
San Diego Mesa Mint
San Diego Mesa Mint
dry vernal pool
Vernal Pool, Dry Phase

Where wildlife comes naturally!

Last updated: May 19, 2009