Long before there was an “Atascadero Lake”, the small, shallow basin which was to eventually become the Lake, naturally filled with the winter rains and then, just as naturally, receded during the summer heat. Atascadero “Lake” is actually a pond; a low-lying area fed by rainfall and run-off. Please see this link for information about the Salinan tribe of Native Americans and their connection to Atascadero Lake.
As part of his dream for the Colony of Atascadero beginning in 1913, E.G. Lewis had engineers enlarge the existing natural basin, and then he featured the Lake in his promotions to help draw people to the new Colony. As in the past, Atascadero Lake continues to fill each year during the rainy season and then slowly dries as the summer progresses.
In times of limited rain or drought, the water level in Atascadero Lake is much lower than when we’ve had a good, wet season. Without enough rain to create a significant runoff, the lake doesn’t have a chance to fill to capacity, and then the water level sinks much more rapidly in natural response to the warm and semi-arid climate we normally experience here in Atascadero.