![[logo] US EPA](https://webarchive.library.unt.edu/eot2008/20090509033326im_/http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
Case Study: Impairments and Loads
Table of Contents
The designated use for this waterbody is secondary contact recreation, and applicable water quality criteria for fecal coliform bacteria are:
- 200 cfu/100ml - 30-day Average for each month, and
- 400 cfu/100ml - 30-day 90% upper-bound for each month
- 2000 cfu/100ml - not to be exceeded at any time.
Current instream concentrations exceed these criteria, implying the need for abatement action and load reductions. There are three principle stakeholders responsible for fecal coliform loads (see below), and a variety of best management practices (BMPs) and technology options are available for reducing these loads.
| Stakeholders | Bacteria Sources (details) |
|---|---|
| Hog and Dairy Operations | Manure Applied to Cropland |
| Beef Cattle | Runoff from Dry Lots, and Cattle Wading in the Stream |
| Wastewater Treaters | Failing Septic Systems, and Wastewater Treatment Plant |
Baseline conditions indicate that 75% of the current fecal coliform load is attributable to beef cattle operations. Baseline loads from hog and dairy operations are relatively small compared to loads from wastewater treaters and beef cattle operations (see figure 1).
Figure 1: 75% of average daily baseline load is due to beef cattle operations, while 22% of baseline load is due to wastewater treaters.
Note that aquatic loads refer to the bacteria numbers at the instream monitoring point that can be attributed to each source.
Fecal coliform concentrations are highly seasonal due, in part, to weather patterns and current manure management practices. 30-day average concentrations exceed the average criterion of 200 cfu/100ml from April to July, as well as September, but drop as low as 110 cfu/100ml in February (see figure 2). The highest concentrations occur in May when the average is 5,800 and the maximum approaches 80,000 cfu/100ml.
Figure 2: Average, upperbound, and maximum criteria for fecal coliform bacteria are exceeded in many months under baseline conditions, particularly April to July.
« Case Study | Source Loads | Allocations »