Assessment of possible sources of microbiological contamination in the water column and streambed sediment of the Jacks Fork, Ozark National Scenic Riverways, Missouri : Phase III

Davis, J; Barr, M

A study to better understand the extent and sources of microbiological contamination within the Jacks Fork from Alley Spring to the mouth, which includes the 7-mile 303(d) reach. The U.S. Geological Survey, in cooperation with the National Park Service, conducted a study to better understand the extent and sources of microbiological contamination within the Jacks Fork from Alley Spring to the mouth, which includes the 7-mile 303(d) reach. Identification of the sources would provide the National Park Service and the State of Missouri with the information needed to craft a solution of abatement, regulation, prevention, and mitigation with the end result being reduction of bacterial levels and removal of the Jacks Fork from the 303(d) list. Ten sites were sampled from June 2003 through October 2003 and from June 2004 through October 2004. Samples were collected from main-stem and tributary sites mostly during base-flow conditions during a variety of recreational season river uses. Water-column and streambed-sediment samples were analyzed for fecal coliform and Escherichia coli (E. coli) bacteria; sieve analysis also was performed on selected streambed-sediment samples to determine particle-size distributions at each sampling location. During the sampling period, the Statewide whole-bodycontact recreation standard for fecal coliform (200 colonies per 100 milliliters of sample) was exceeded at two sites on August 6, 2003; at one site on October 8, 2003; and at two sites on August 11, 2004. Each of these exceedences occurred in samples collected when trail rides occurred. The Eminence Wastewater Treatment Plant may have contributed to one of the exceedences on August 6, 2003, at a site immediately downstream from the plant because of large fecal coliform densities in the effluent. To compare the effects of intense trail-ride activity and large volumes of recreational boaters and swimmers on fecal indicator bacteria densities, hourly sampling for fecal coliform and E. coli bacteria was done at site 110 on selected weekends when no trail rides were taking place, and on weekdays during trail rides. Generally, the fecal indicator bacteria densities tended to decrease or stay somewhat constant as the number of canoes, kayaks, and tubes passing site 110 increased. During trail rides, the fecal coliform bacteria densities generally tended to increase as the number of horses crossing the river increased, and decrease with a decrease in the number of horses crossing the river. Because bacteria can survive longer in streambed sediments than in water, a source of bacteria in the water column could be from resuspension of accumulated bacteria from streambed sediments. Streambed-sediment samples were collected at all Jacks Fork main-stem and tributary sites and analyzed for fecal coliform and E. coli bacteria. The largest fecal coliform bacteria densities in the water column and streambed sediment generally occurred during trail rides. The relation of fecal coliform density in the water column to fecal coliform density in streambed sediment had a small positive correlation. The relation of fecal coliform density in streambed sediment to sediment particle size of less than 2,000 micrometers had a positive correlation. Results indicate that recreational users (including boaters and swimmers) are not the primary source of fecal coliform bacteria in the Jacks Fork; rather, the presence of fecal coliform bacteria is associated with other animals, of which horses are the primary source. Increases in fecal coliform bacteria densities in the Jacks Fork are associated with cross-country horseback trail-riding events.

Assessment of possible sources of microbiological contamination in the water column and streambed sediment of the Jacks Fork, Ozark National Scenic Riverways, Missouri : Phase III

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