By Saige White

If you’ve lived in California’s Central Valley for at least a few years, you may have heard the term, ‘vernal pool’. Not known to many, California’s vernal pools are a rare type of wetland that exist in very few places on Earth.

Found in rolling grasslands around the Sacramento area, vernal pools are temporary, which sets them apart from other wetlands, ponds, or lakes. For 6-8 months of the year they are completely dry and barren. During the rainy seasons, vernal pools fill with water.

In grasslands, water that falls during the rainy season sinks into the ground or flows slowly over the land as runoff (generally into a stream or river).

However, when water in a vernal pool grassland cannot absorb any farther into the ground or runoff into the rivers, it begins to saturate and fill various depressions that exist in the grassland. Vernal pools are these filled depressions.

As the seasons begin to change and we go from the rainy season to spring, the grasslands begin to dry, but the vernal pools still contain some water. Wildflowers begin to form around the pools, creating an eye-catching display. In these pools, a host of wildlife exist and utilize the water as habitat. Many of them are unique and threatened by extinction, such as  Fairy shrimp, California tiger salamander, and Tadpole shrimp.

Once summer approaches, the water evaporates and dries. Though it’s easy to assume the summer months hold less importance during the life cycle of the vernal pool, it’s actually quite the opposite. The pools provide birds, mammals, and insects with seeds and bulbs to feed on during this time. The bottoms of the vernal pools also hold the eggs, cysts, and seeds that will give life to the next generation.