This is the third in a series of articles about the Pomme de Terre Watershed and the TMDL studies that are now underway studying the pollution problem in the watershed.
"Poo bacteria" is what the host of "Dirty Jobs" would probably call it. Fecal Coliform is an all encompassing name for a group of several different kinds of bacteria and other microorganisms found in the intestines of warm-blooded animals and is always associated with fecal matter.
Certain strains of fecal Coliform bacteria can be extremely pathogenic. One such strain is E. coli O157:H7, which is found in the digestive tract of cattle. This is the strain that is in the news periodically for causing outbreaks of illnesses, and in a few cases, even death, usually from ground beef tainted with the bacteria.
Ingestion of E. coli can lead to severe gastrointestinal illness such as severe diarrhea, nausea, headaches and fatigue.
MN statutes regarding the fecal Coliform water quality standard for class 2B waters, which is what the Pomme de Terre River is classified as, states that fecal Coliform concentrations shall not exceed a monthly average of 200 organisms per 100 ml of water, and a maximum of 2,000 organisms per 100 ml of water not to exceed 10 percent of samples collected in a month. The MPCA is in the process of changing the fecal Coliform standard to an E. coli standard. So instead of looking at fecal Coliform in general, they will be specifically looking for E. coli , which has been determined to be the preferred indicator of the potential presence of waterborne pathogens.
The Federal Clean Water Act has the goal of providing waters that are "fishable and swimmable." The fecal Coliform standards protect the surface waters for the "swimmable" portion of this goal. Water recreation is divided into two categories, primary and secondary body contact. Primary body contact includes swimming, diving, water skiing, or any form of recreation where the possibility of ingesting water is likely. Secondary body contact recreation includes boating, fishing, sailing, canoeing, and wading. The chance of ingesting water in these activities is much smaller. The fecal Coliform standards are only applicable during the warm months since there is very little primary body contact with water in Minnesota during the non-summer months. Primary body contact with water in January would probably lead to bumps and bruises, rather than diarrhea.
Monitoring data shows that the lower portion of the Pomme de Terre from Muddy Creek down to Marsh Lake to be impaired for fecal Coliform bacteria. Where is this coming from? Pathways include direct routes to surface waters such as failing or illegal septic system connections, municipal wastewater treatment facility discharge points, and urban storm water systems, spills or runoff from livestock housing or manure storage facilities, runoff from agricultural lands that receive manure applications, runoff of wildlife, or domestic pet droppings and direct deposition into waterways by wildlife or grazing animals. Manure management practices, including manure storage and pretreatment, timing and rate of application, and application method, all have the potential to reduce bacteria contamination of surface water.
Some of the sources can be considered continuous sources, that is, they will discharge fecal Coliform no matter what the weather is like. Failing septic systems, municipal wastewater treatment facilities, and cattle with access to streams are all considered continuous sources of fecal Coliform. It is estimated that 50 percent of the rural households in the watershed have out-of-compliance septic systems. Of these, 25 percent, or 435 households, have septic systems that directly discharge to tile.
Other sources tend to be precipitation driven due to runoff from rainfall. Feedlot runoff, pasture runoff, manured fields and urban storm water are all sources that discharge more fecal Coliform when it rains. According to the 2003 MPCA feedlot data base, there are over 63,897 animal units in the watershed, mainly dairy, beef, swine and turkey.
When fecal Coliform levels in the watershed are compared with rainfall data from the National Weather Service, there is a strong positive correlation between precipitation and fecal Coliform bacteria concentrations. When storms occur, weather-driven sources (feedlot runoff, overgrazed pasture runoff, manured fields, and urban storm water) overshadow continuous sources like failing septic systems, wastewater treatment facilities and cattle in streams. This suggests that readily available fecal Coliform sources are storm event driven, and runoff from rain events is the primary delivery mechanism in wet periods.
So in the Pomme de Terre Watershed, our main sources of fecal Coliform are failing individual septic systems, open feedlots under 1,000 animal units without runoff controls, manure application at the wrong time and/or the wrong place, manure stockpiles without runoff controls, and pastures without runoff controls.
It may surprise some people that the large dairies and cattle operations in the southern part of the watershed are not considered to be major sources of fecal Coliform bacteria. As I mentioned in my last article, large Confined Animal Feeding Operations (CAFOs) are regulated under the NPDES point source permit system, as such, they are required to take measures to ensure they do not discharge fecal Coliform into area surface waters. These producers have been very proactive in taking measures and implementing practices to ensure this does not happen.
Municipal Waste Water Treatment Plants are also not considered to be a concern because they are also regulated by the NPDES permit system and are held to a discharge standard.
Shaun McNally is the Pomme de Terre Watershed Project Coordinator. He is located in the Stevens SWCD office in Morris (320-589-4886 ext. 109)
The Pomme de Terre River Association maintains a website: www.pdtriver.org