SOUTH DAKOTA Department of
Environment & Natural Resources

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Surface Water

Summarizing the Data on a DMR


SD's Surface Water Discharge permits require that the analysis results from a discharge be reported on a Discharge Monitoring Report (DMR) form. To understand how to properly report these results, we must first understand a couple of terms and how they relate to DMR reporting:

      You must use a geometric mean instead of a 30-day average for total and fecal coliform values. 

The method to calculate a geometric mean will be explained below. 

The Daily Maximum, 7-Day Average, and 30-Day Average are the most common methods that most facilities have to report the data on their DMR. Many facilities are also required to report a Geometric Mean. 


The best method for demonstrating how to calculate and report these values is by providing an example. 

The city of Townsville has a lagoon system for treating its wastewater and conducts periodic discharges from its facility. During a discharge, the city is required to sample three times the first week and once per week the following weeks until the discharge is terminated. The city is required to sample for Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS), Ammonia, Fecal Coliform, pH, and Temperature. The city is also required to record and report its flow rate.

The city began discharging on the Monday May 28th, and completed its discharge on June 15th. Let's see how the city filled out its DMR: