Groundwater in the Sweetwater River Drainage

Problem

No comprehensive geologic and hydrologic study has been made of the San Diego area. As a result it is difficult for state and federal agencies, water purveyors, and consultants to understand the effects of urbanization on the local surface-water, groundwater, and biologic resources or to critique ideas and opportunities for additional ground-water development. This study will initiate the process of providing an integrated geology and hydrology understanding of this important and highly visible area of the United States.

Objectives

The two primary objectives of this study are (1) to develop an integrated, comprehensive understanding of the geology and hydrology of the San Diego Formation and the overlying alluvial deposits, and (2) to use this understanding to evaluate expanded use of the alluvial deposits and San Diego Formation for recharge and extraction. Secondary objectives include to:

• Define the occurrence and geologic history of the San Diego Formation;
• Define the hydrogeologic characteristics of the San Diego Formation and the overlying alluvial deposits, including areal and vertical variations;
• Define the water-quality characteristics of the San Diego Formation and the overlying alluvial deposits;
• Define the age and movement of groundwater through the San Diego Formation and overlying alluvial deposits; and
• Develop an integrated hydrogeologic framework for the area encompassing the San Diego Formation and overlying alluvial deposits; and
• Describe, and to the extent possible quantify, the interaction of biologic and hydrologic resources in the Sweetwater River channel.

Because the San Diego Formation is largely unstudied and areally extensive, this study initially will provide only partial attainment of the above objectives. The study is designed, however, to be expandable so that initial findings can be integrated into a much more complete understanding of the hydrologic and biologic resources of the San Diego area. For example, findings from this study will be integrated with those of three other ongoing USGS studies in the area.

Relevance and benefits

This study will benefit the cooperator, the Sweetwater Authority, by providing an improved understanding of the source of water to their production wells and the interaction of their production wells with near-surface groundwater in the riparian, alluvial channel of the Sweetwater River. Benefits to others in the San Diego region will be from having a comprehensive investigation of the primary aquifer of the region. Benefits to the nation include quantifying the resources of an important coastal city, and developing the background information necessary to understand a complex coastal biologic-hydrologic environment. This study will address five issues in the Strategic Directions for the USGS Water Resources Division, 1998-2008. Specifically, the study will provide information about Issue 1 (Effects of urbanization and suburbanization on water resources), Issue 2 (Effects of land use and population increases on water resources in the coastal zone), Issue 3 (Drinking water availability and quality), Issue 8 (Surface-water and groundwater interactions as related to water-resource management), and Issue 9 (Hydrologic-system management, including optimization of groundwater and surface-water use).

Approach

To achieve the primary objectives requires (1) collection and analysis of new data, in particular new types of data such as naturally occurring stable and radioactive isotopes found in groundwater; (2) exhaustive review of existing literature and interpretative work, and (3) development of comprehensive concepts that integrate geologic, hydrologic, and water-quality data. The study involves three phases. Phase I, which has been initiated, involves limited water-quality data collection mostly from existing production wells in Chula Vista. Phase II involves expanded water-quality sampling including from National City wells, development of a Geographical Information System, and presentation of data on a website. Phase III involves literature review, analysis of satellite InSAR data, aquifer tests, installation of a multiple-depth monitoring well, and preparation of a report.

Project Chief: Wes Danskin
Phone: 619-225-6132
Email: wdanskin@usgs.gov

Welcome to the United States Geological Survey (USGS) San Diego Hydrogeology (SDH) 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: July 2023.

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