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University of Iowa News Release

 

Nov. 12, 2009

Private rural drinking water well study results released

The newly released Iowa Statewide Rural Water Well Survey Phase 2, which examined the water quality of private rural drinking water wells, shows continuing problems with nitrate and bacterial contamination.

The survey, which was led by the University of Iowa Center for Health Effects of Environmental Contamination, also reveals that a high percentage of wells statewide were contaminated with arsenic.

"The nitrate and bacteria results were expected despite efforts to address contamination in groundwater sources. The arsenic results were something we did not expect," said Peter Weyer, Ph.D., the study's lead investigator and associate director of the UI Center for Health Effects of Environmental Contamination. "Nearly half the wells sampled had some level of arsenic, and 8 percent of those had a level that could be considered a health concern.

"On a more positive note, the levels of the commonly used herbicide atrazine seem to be trending downward from what past studies have shown," Weyer added.

The survey, conducted from 2006 to 2008, sampled 473 wells statewide for bacteria, nutrients, metals, common use herbicides and insecticides, and herbicide degradates. This study was a follow-up effort to the original Statewide Rural Water Well survey, known as SWRL, that was conducted from 1988 to 1989.

Additional findings from the sampled wells in the latest study include:
--43 percent of the samples had total coliform bacteria, 19 percent had enterococci and 11 percent hadE. coli.
--49 percent had nitrate, with 12 percent having more than 10 parts per million of nitrate-N, which is the Safe Drinking Water Act standard for public water supplies.
--48 percent had arsenic, with 8 percent having arsenic above the Safe Drinking Water Act standard for public water supplies.
--8 percent had atrazine at very low concentrations and 2 percent had metolachlor.
--One or more of the pesticides acetochlor, alachlor and trifluralin were detected in less than 1 percent of wells.
--Analysis of herbicide degradates (breakdown products of the parent compound) included the finding that 11 percent of water samples had desethylatrazine, 11 percent had acetochlor ESA (ethane sulfonic acid), 27 percent had alachlor ESA, 33 percent had metolachlor ESA and 8 percent had metolachlor OXA (oxanilic acid).

"While the herbicide degradates are widespread, most of the detection levels are very small -- in the sub-part per billion range," Weyer said. "In addition, there are no drinking water standards established for these breakdown products."

Degradates are generally believed to be less toxic than the parent compound.

The Iowa Statewide Rural Water Well Survey Phase 2 was a joint effort among many statewide organizations, including Iowa private well owners, Iowa county public/environmental health departments, University Hygienic Laboratory, UI College of Public Health, Iowa Department of Natural Resources, Iowa Department of Public Health, Iowa Department of Agriculture and Land Stewardship, U.S. Centers for Disease Control and Prevention, ISU Department of Geologic and Atmospheric Sciences, and the UI Center for Health Effects of Environmental Contamination.

A full report of the latest survey is available for download through the UI Center for Health Effects and Environmental Contamination Web site at
http://www.cheec.uiowa.edu/research/SWRL2.html.

Private drinking water wells are not required to meet any drinking water quality standard, unlike public supplies. Owners of private drinking water wells are eligible for free testing for nitrate and bacteria through the statewide Grants-to-Counties Program. They can visit http://www.uhl.uiowa.edu/services/wellwater/gtc.xml or contact their county public health department for further information.

STORY SOURCE: University of Iowa Health Care Media Relations, UI Health Care Media Relations, E110 GH, 200 Hawkins Drive, Iowa City, Iowa 52242

MEDIA CONTACT: Peter Weyer, University of Iowa Center for Health Effects of Environmental Contamination, 319-335-4014, cheec@uiowa.edu; Writer: David Riley