Nitrate Testing
In the winter of 2004-2005, EDWDD conducted a pilot project to test nitrate levels in water from private wells across the area. The District purchased a Hach DR/4000 spectrophotometer, which has the capability to analyze water samples for nitrate with minimal sample pre-treatment. The device was used to test water samples at local farm and home shows as an alternative to having well owners send samples off for analysis. Nitrate testing clinics were held in DeSmet, Milbank, Clear Lake, Howard and Watertown. A clinic was also held at the September 2005 Annual Meeting of the South Dakota Association of Conservation Districts in Sioux Falls.

Additional testing using the spectrophotometer was conducted in support of investigations of local public water supplies. Samples collected in the area around Estelline in November 2004 were analyzed as part of an effort to identify potential new well locations. A series of analyses were conducted to monitor the presence of nitrate in the drinking water system for the Town of Trent in July and August of 2005. Nitrate levels in the towns primary source had exceeded legal limits, and an alternate supply was engaged while a new source was sought. Samples taken from Minnehaha Community Water Corporation and the Clay Rural Water System wells were analyzed in August and September 2005 (respectively) to monitor nitrate in their primary aquifers.

A total of 238 samples were analyzed during these events, with results ranging from non-detectable (below 0.1 mg/L) to as high as 65 mg/L N-NO3. 30 quality assurance/quality control samples were collected at the events listed above. They were submitted to the Olson Biochemistry Laboratory at South Dakota State University for nitrate analysis. Results from 29 of the samples analyzed by the lab were within five percent (5%) of the field readings. The lone aberrant is believed to have been the result of a miscalculation of the field results by the operator.

Based on the success of this program, the District purchased a second testing unit and continues to make the resource available to area groups for testing of nitrates. One device is currently on loan to the Groundwater Quality Program of the South Dakota Department of Environment and Natural Resources. They are conducting similar testing clinics on a state-wide basis.
For information on the program, or to set up a clinic in your area, contact Jay Gilbertson.