Hydrology of Vernal Pools at Three Sites, Southern Sacramento Valley

The subsurface hydrology of vernal pools at three vernal pool complexes was investigated during three wet seasons in 2002-2004. The complexes were at Gridley Ranch, Valensin Ranch, and the Mather Field in northern California. The selected complexes provided variation in soils, landforms and topography. Three vernal pools were chosen in each complex based on variation in pool type, size, and position in the drainage system. The objectives were to describe the subsurface hydrology of vernal pools to refine the conceptual model of vernal pool hydrology and to answer questions about: the size of watershed support for vernal pools, the importance of the watershed and drainage system to the vernal pools, the possible effects of truncating the watershed or eliminating upstream pools, the potential role of perched aquifers, and subsurface connections among pools, in controlling the length of inundation. The vernal pools studied demonstrated markedly different hydrologic behaviors due to variation in topography and soil properties near the pools. The hydrologic behavior of vernal pools has important implications for land use practices and for impact remediation efforts. Additional research is needed to refine our understanding of vernal pool hydrology