Groundwater and Surface Water Interactions at the Tijuana Estuary, San Diego County, California - The Tijuana Estuary is a unique coastal plain and wetland-dominated estuary influenced by tidal fluctuations and saltwater inflow from the Pacific Ocean and by intermittent freshwater inflow from the Tijuana River. The lower Tijuana River valley, the alluvial river valley that leads into the estuary, collects 96% of runoff in the 4,500 km2 Tijuana River watershed. Stream flow in the Tijuana River...