U.S. Geological Survey
By Roy L. Glass
As part of the U.S. Geological Surveys National Water-Quality Assessment Program, ground-water samples were collected from 34 existing wells in the Cook Inlet Basin in south-central Alaska during 1999. All ground-water samples were from aquifers composed of glacial or alluvial sediments. The water samples were used to determine the occurrence and distribution of selected major ions, nutrients, trace elements, volatile organic compounds, pesticides, radioisotopes, and environmental isotopes. Of 34 samples, 29 were from wells chosen by using a grid-based random-selection process. Water samples from five major public-supply wells also were collected.
Radon-222 and arsenic concentrations exceeded drinking-water standards proposed by the U.S. Environmental Protection Agency in 39 and 18 percent of sampled wells, respectively. The highest radon concentration measured during this study was 610 picocuries per liter; 12 of 31 samples exceeded the proposed maximum contaminant level of 300 picocuries per liter. The highest arsenic concentration was 29 micrograms per liter; 6 of 34 samples exceeded the proposed maximum contaminant level of 10 micrograms per liter. Human activities may be increasing the concen- tration of nitrate in ground water, but nitrate concentrations in all samples were less than the maximum contaminant level of 10 milligrams per liter as nitrogen. Concentrations of nitrate were highest in Anchorage and were as great as 4.8 milligrams per liter as nitrogen. Dissolved-solids concentrations ranged from 77 to 986 milligrams per liter; only 2 of 34 wells yielded water having greater than 500 milligrams per liter. Iron and manganese concentrations exceeded secondary maximum contaminant levels in 18 and 42 percent of samples, respectively.
Concentrations of all pesticides and volatile organic compounds detected in ground-water samples were very low, less than 1 microgram per liter. No pesticide or volatile organic compounds were detected at concentrations exceeding drinking-water standards or guidelines. Water samples from one-half of the wells sampled had no detectable concentrations of pesticides or volatile organic carbons, at the parts-per-billion level.
Concentrations of stable isotopes of hydrogen and oxygen in ground-water samples were similar to concentrations expected for modern precipitation and for water that has been affected by evaporation. Tritium activities and concentrations of chlorofluorocarbons indicated that the water samples collected from most wells were recharged less than 50 years ago.
Purpose and Scope
Major Water-Quality Issues
Environmental Setting ahd Hydrologic Conditions
Methods of Investigation
Water-Quality Standards and Guidelines
Physical Properties and Field Measurements
Nutrients and Dissolved Organic Carbon
Volatile Organic Compounds
Stable Isotopes of Hydrogen and Oxygen
Age Dating of Ground-Water Recharge
For your convenience, this report is provided here in Portable Document Format (PDF).
Adobe Acrobat Reader is available for free download from Adobe Systems Incorporated.
Download the cover Cover -- PDF (104 KB).
Download main text of report as a PDF document (2.27 KB).
You may want to visit the Adobe website, which offers conversion tools and information to help make PDF files accessible.
Download a free copy of Adobe Acrobat Reader version 5.0
For questions about the content of this report, contact Roy L. Glass
Note: Do the following in order to force download to a hard drive: For Macintosh users, click on the desired data file but hold the mouse button down for a moment to display a pop-up menu. Select "Save this link as..." (Netscape Navigator) or "Download Link to Disk" (Internet Explorer), then navigate to where you want the file to be saved. For Windows users, use the right mouse button to display a pop-up menu, select "Save Link As..." (Netscape Navigator) or "Save Target As..." (Internet Explorer), and navigate to where you want the file saved.
This report is also available from:
USGS Information Services, Box 25286,
Federal Center, Denver, CO 80225
telephone: 303-202-4210; e-mail: firstname.lastname@example.org
|AccessibilityFOIAPrivacyPolicies and Notices|
|U.S. Department of the Interior, U.S. Geological Survey
Persistent URL: http://pubs.water.usgs.gov/wri014208
Page Contact Information: Contact USGS
Last modified: Thursday, September 01 2005, 05:02:39 PM