San Diego Hydrogeology Study Area Boundary

This dataset was created in December of 2014 to replace the previous study area boundary also containing 5 major drainage basins plus an area of the offshore region where groundwater is presumed to flow. The purpose for this update is to incorporate a new topographic/bathymetric grid that was created with most recent elevation data available. This revised  topographic/bathymetric dataset changed the contour line at the western edge of the study boundary that was used to create a portion of the previous boundary.

A re-evaluation of the portion of the study area that extends into the ocean was completed to ensure the criteria used for creating the boundary could be described with valid reasoning.

Several options were considered and among those options a 1000 foot depth contour was considered since there is a plateau that drops from about 350 feet to around 1000 feet and is mostly consistent along the shoreline from north to south of that portion. The consideration of the 1000 foot depth contour was dismissed since the belief of groundwater flow may extend deeper and beyond this small plateau edge.

The 2800 foot depth encompasses a larger plateau known as the Continental Shelf. At a depth of 2800 feet below mean sea level, this contour is an average depth from the northern watershed edge to the southern for a location at the base of the continental slope. In the far southern portion of the study area portion that extends into the ocean, the base of the Continental Shelf is near 3200 feet below MSL and near the northern portion the ocean currents have made the slope nearly impossible to trace.

The connecting north and south boundary lines from the 2800 foot depth up to the Watershed Boundary Dataset were hand drawn by Wes Danskin to represent the edge of the watershed if the ocean water were removed.

Project Chief: Wes Danskin
Phone: 619-225-6132

Welcome to the United States Geological Survey (USGS) San Diego Hydrogeology project website, which provides geologic and hydrologic information for the transboundary San Diego–Tijuana area, USA and Mexico. This website provides background information about the project; a variety of news items; a large amount of data, in particular for USGS multiple-depth, monitoring-well sites; geologic and hydrologic models; and additional resources including photos, illustrations, and references. Last updated: April 2016

Some additional data may be available from the USGS database National Water Information System (NWIS).

Questions about San Diego Hydrogeology? Please contact Wes Danskin (email: or send a letter). 619.225.6132