Biologist Christopher Richard has researched waterways throughout the Bay Area. This is his map of the water flow in the Mission District. It includes historic streams, tidal inlets and marshlands that no longer exist in the urban environment.The dark blue shows where the tidal inlet was, and the light blue is shallow seasonal wet areas.The black map is a replica of the historical monument displayed at the intersection of Camp and Albion, showing a freshwater lake that Richard disputes. From http://missionlocal.org/2011/02/unraveling-the-mystery-of-lake-dolores/