USGS


Determining Age and Vertical Contribution of Ground Water Pumped from Wells in a Small Coastal River Basin

A Case Study in the Sweetwater River Valley, San Diego County, California

By Wesley R. Danskin and Clinton D. Church

 

Prepared in cooperation with the Sweetwater Authority

 

U.S. GEOLOGICAL SURVEY

Open-File Report 2005-1032

Sacramento, California 2005



Complete accessible text of report (10,288 KB PDF)

To view PDF documents, you must have the Adobe Acrobat Reader (free from Adobe Systems) installed on your computer.
(download free copy of Acrobat Reader).

Abstract

   The age and vertical contribution of ground water flowing into four municipal supply wells were determined under pumping conditions in order to better understand the source of water to the wells. Vertical flowrate inside the wells, located in the Sweetwater River drainage basin of San Diego County, California, was measured at selected depths using a dye-injection technique. Flowmeter results indicate that as much as about half the pumped water comes from the alluvial deposits and half from the underlying San Diego Formation. Chemical analysis of water samples collected at specific depths support this vertical distribution of pumped water. Tritium and carbon-14 data indicate that ground water from the alluvial deposits was recharged less than 50 years ago, and ground water from the San Diego Formation is thousands of years old, some as much as 16,000 years old.

CONTENTS

Abstract
Study Area
Methods of Investigation
Measuring flow into a well
Sampling water from a well
Analysis of Flow Data
Analysis of Chemical Data
General Chemistry
Chloride-Boron Ratio
Age Dating
Discussion
References


Document Accessibility: Adobe Systems Incorporated has information about PDFs and the visually impaired. This information provides tools to help make PDF files accessible. These tools convert Adobe PDF documents into HTML or ASCII text, which then can be read by a number of common screen-reading programs that synthesize text as audible speech. In addition, an accessible version of Acrobat Reader 6.0 for Windows (English only), which contains support for screen readers, is available. These tools and the accessible reader may be obtained free from Adobe at Adobe Access.

 



Water Resources of California


U.S. Department of the Interior, U.S. Geological Survey
Persistent URL: http://pubs.water.usgs.gov/ofr20051032
Page Contact Information: GS Pubs Web Contact
Last modified: Saturday, January 12 2013, 09:26:47 PM
FirstGov button  Take Pride in America button