Water and Pollution Control Department

Source Water Assessment

Summary

Ames water comes from 22 groundwater wells drawing from the Ames aquifer, which includes both formations classified as "Alluvial" and formations classified as "Pleistocene."  Water drawn from alluvial aquifers is drawn from the geological deposits of the current river valley composed of clay, silt, sand, gravel, or similar material deposited by running water.  Pleistocene aquifers are similar, but have more surface sediment covering a prehistoric buried channel formation. 

Besides groundwater, other sources of drinking water (tap and bottled) are rivers, lakes, streams, ponds, reservoirs, and springs.  All water sources have a potential for contamination.  As water travels over the surface of the land or through the ground, it dissolves naturally occurring minerals and, in some cases, radioactive material.  It can also pick up substances resulting from the presence of people and animals.  

A detailed evaluation of Ames source water was completed by the Iowa Department of Natural Resources in 2003.  Alluvial portions of the Ames aquifer were determined to be highly susceptible to contamination because the characteristics of the aquifer and minimal overlying materials allow contaminants to move through the aquifer fairly quickly.  The Pleistocene formations were determined to be less susceptible to contamination than the alluvial formations because the characteristics of the aquifer and overlying materials limit the rate at which contaminants can move through the aquifer.  The alluvial wells will be most susceptible and the Pleistocene wells somewhat susceptible to activities such as solid waste disposal sites, hazardous waste generators, waste water treatment plants and leaking underground storage tanks.  Hard copies of this report are available at cost or can be reviewed at the City of Ames Water Plant at 300 E. 5th Street, Ames, Iowa.

Watershed protection is a good way for a community to reduce the potential for contamination of the aquifers. Ames has begun encouraging watershed protection with the Ada Hayden Heritage Park constructed wetlands and prairie restoration.  You can help by minimizing the chemicals you use on your lawn and garden and making sure only storm water is put into the storm sewers.

Source water and treated water samples are tested at the Water Plant's Laboratory Services Division and at the University Hygienic Laboratory in Iowa City.  Substances that the water is tested for may be divided into five basic testing groups:

• Microbial contaminants, such as bacteria, which may come from wastewater treatment plants, septic systems, agricultural livestock operations and wildlife.
• Inorganic contaminants, such as salts and metals, which can occur naturally or result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining, and farming.
• Pesticides and herbicides, which may come from a variety of sources such as agriculture, urban stormwater runoff and residential uses.
• Organic chemical contaminants, including synthetic and volatile organic chemicals, which are by-products of industrial processes and petroleum runoff, and septic systems.
• Radioactive contaminants, which occur naturally or result from oil and gas production and mining activities.

Complete Source Water Assessment Documents

IDNR Cover Letter (.pdf, 245 KB)
SWA - Alluvial Aquifer (.pdf, 2.56 MB)
SWA - Pleistocene Aquifer (.pdf, 2.14 MB)

Additional information on the requirements of the SDWA related to source water protection is available from the U.S. Environmental Protection Agency's web site at http://www.epa.gov/safewater/protect.html.  

Information on Iowa's implementation is available from the Iowa Department of Natural Resources' web site at http://www.iowadnr.com/water/drinking/index.html.