On Saturday, April 13, I, Josh Trotter, an intern with BPC, visited the Elsie Gridley Mitigation Bank managed by WRA. The mitigation bank was established for the purpose of maintaining/restoring vernal pool grassland and riparian habitats, as well as habitats for a number of rare, threatened, and endangered species. Establishment of the bank enables the sale of wetland credits as mitigation for wetland impacts in the service area, and conservation credits on the bank site.
WRA members gave us a guided tour through a small portion of the 1837 acres (~3 mi2 / ~7 km2) of wetlands comprising the bank. About two weeks ago the now desiccated vernal pools were filled with small puddles. Early in the year the pools are home to a number of spawning species, including Vernal Pool Fairy Shrimp (threatened), Vernal Pool Tadpole Shrimp (endangered), Baker’s Navarretia, and Dwarf Downingia. Vernal pools are characterized by the presence of prolonged standing water due to their impermeable soils.
“They are shallow, less than 18 inches in depth, with clear to tea-colored water. Vernal pools also typically support extensive populations of common vernal pool species such as woolly marbles (Psilocarphus brevissimus var. multiflorus), stipitate popcornflower (Plagiobothrys stipitatus), vernal pool buttercup (Ranunculus bonariensis), mesa mint (Pogogyne sp.), coyote thistle, hairgrass (Deschampsia danthonioides), goldfields (Lasthenia spp.), downingia (Downingia spp.), Pacific meadow foxtail (Alopecurus saccatus), and little spike-rush (Eleocharis acicularis).”
To keep the bank’s grasslands in check, the bank’s owners devised an elegant win-win agreement with a local farmer: they hold the land rights, leaving grazing rights to the farmer’s cows. In fact, having ruminants graze preserves a 40,000 year natural management pattern: prior to human agriculture, elk, deer, and other grazing fauna were the natural stewards of the grasslands.
As wetlands are converted to farmland or urban sprawl, natural phenomena like vernal pools and their associated species become increasingly rare features in an increasingly industrialized California landscape. The regional map (above) marks immense cross-county vernal pool regions that, unless they are recognized and properly maintained, will be lost. Mutually-beneficial solutions to both environment and agriculture like the maintenance agreement described above are essential for developing food sources while preserving a healthy ecosystem.
The BPC thanks WRA and AEP East Bay and Superior Chapters for hosting this enlightening field trip.