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The Effect of Calcium Magnesium Acetate (CMA) Deicing Material on the Water Quality of Bear Creek, Clackamas County, Oregon, 1999

By Dwight Q. Tanner and Tamara M. Wood

USGS Water-Resources Investigations Report 00-4092, 22 pages, 9 figures, 4 tables

Report availability


This report presents the results of a study by the U.S. Geological Survey, done in cooperation with the Oregon Department of Transportation (ODOT), to evaluate the effects of the highway deicing material, calcium magnesium acetate (CMA), on the water quality of Bear Creek, in the Cascade Range of Oregon. ODOT began using CMA (an alternative deicer that has fewer adverse environmental effects than road salt) in the mid-1990s and began this study with the USGS to ensure that there were no unexpected effects on the water quality of Bear Creek. Streamflow, precipitation, dissolved oxygen, pH, specific conductance, and water temperature were measured continuously through the 1998-99 winter.

There was no measurable effect of the application of CMA to Highway 26 on the biochemical oxygen demand (BOD), calcium concentration, or magnesium concentration of Bear Creek and its tributaries. BOD was small in all of the water samples, some of which were collected before CMA application, and some of which were collected after application. Five-day BOD values ranged from 0.1 milligrams per liter to 1.5 milligrams per liter, and 20-day BOD values ranged from 0.2 milligrams per liter to 2.0 milligrams per liter.

Dissolved copper concentrations in a small tributary ditch on the north side of Highway 26 exceeded the U.S. Environmental Protection Agency aquatic life criteria on three occasions. These exceedances were probably not caused by the application of CMA because (1) one of the samples was a background sample (no recent CMA application), and (2) dissolved copper was not detected in Bear Creek water samples to which CMA was added during laboratory experiments.

Report availability:

This report is available online. Download the report (PDF, 380 KB) (Adobe PDF Reader required; version 5 or higher preferred.)

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A printed version of the full report is available free (while supplies last) from:

U.S. Geological Survey, 10615 S.E. Cherry Blossom Drive, Portland, OR 97216 (ph: 503-251-3201, e-mail

and (at a nominal charge) from:

U.S. Geological Survey, Information Services, Box 25286, Denver, CO 80225 (ph: 1-888-ASK-USGS, e-mail

Note: When ordering the report, please supply the report title and number, your name, and your mailing address. Thank you.

Bear Creek CMA Project page
Oregon District Online-Publications Page
Oregon District Home Page

U.S. Geological Survey
Last modified: 11/2/99