Land use practices and elevated levels of Escherichia coli in the Coosawattee river, Georgia.
Because fecal coliform bacteria levels have exceeded Georgia Water Quality Standards over the last ten years, portions of the lower Coosawattee Riven Georgia, are listed as impaired by the state of Georgia and do not support its recreational-use designation. The suspected cause of elevated fecal bacteria is the location of agriculture areas adjacent to the river's bank and poor management practices. Escherichia coli (E. coli) bacteria are a subset of the fecal coliform bacteria group and because fecal coliform bacteria were elevated in the lower Coosawattee River, were probably elevated as well. Fecal coliform and E. coli bacteria are not typically pathogenic in water, but indicators of fecal contamination whose presence increases the possibility of illness in humans using the water. In order to assess E. coli densities in the Coosawattee River. 60 water samples were collected on the main river (some near tributary inflow) and analyzed along 75 km of river. Eight of the 60 water samples analyzed for E. coli produced inconclusive results due to improper incubation temperatures. The E. coli results were plotted on satellite imagery and compared to elevated levels and land use. In this paper, elevated levels are those that are >235 cfu/100 ml as established by United Stated Environmental Protection Agency (USEPA) for single-sample beach criterion. Of the samples collected, 15% exceeded the USEPA criterion for E. coli. All of the samples containing > 235 cfu/100 ml were collected in the lower Coosawattee and are adjacent to agricultural land use. This study makes reiterates unacceptable levels of E. coli contamination in the lower Coosawattee River due to non-point sources.
Key words: Coosawattee River, Escherichia coli, land use planning, non-point source contamination
Escherichia coli (E. coli), one of several bacteria comprising the fecal coliform group, are gram negative bacteria most commonly found in the digestive tracts of humans and other warm blooded animals (1). There are several different strains of E. coli, many of which are not harmful to humans. Some strains, however, can cause serious illness such as diarrhea, respiratory illness, and pneumonia (2). Death may result if these symptoms go untreated. Although the E. coli in water itself often poses no risk to humans, its fecal coliform status can be indicative of the presence of other pathogens that are spread through fecal oral contamination. Because E. coli exists in mammal feces its presence in water sources is considered the most reliable indicator of fecal contamination (3). Since 1986 the Environmental Protection Agency (EPA) recommended E. coli as the preferred indicator bacteria for fresh water (4). This policy is based on epidemiological studies showing a statistical relationship between swimmer-associated illness rates and levels of E. coli in water. The state of Georgia, however, still reports information and results for only fecal coliform (EC).
The Clean Water Act requires that states classify their open water bodies based on primary usage (such as drinking water, recreation, fishing). For each designated use the EPA recommends acceptable limits for E coli based on two thresholds: (1) a geometric mean calculated from five samples collected within a 30-day period, and (2) a maximum value from a single sample. Water sources may be contaminated with E. coli because of faulty septic systems, runoff from livestock in close proximity to water bodies, and land-applied manure or other biosolids. Moreover, the collection of water samples during dry conditions is extremely important as surface runoff can elevate the presence of E. coli in river systems (5).
The Coosawattee River is located in the Coosa River Basin and within the Blue Ridge and Ridge/Valley geological providences in Georgia. The Coosawattee is separated into an upper (35 km) and lower portion (40 km) by a man-made reservoir called Carter's Lake (Figure 1). The river is a tributary of Oostanaula River and the raising of livestock (beef and poultry) and farming (apple orchards) are the primary agricultural activities in the Coosawattee River basin (personal communication. Ellijay Chamber of Commerce). The river is classified as recreational by the EPA (6). This designation is likely because of the many people who use the river to canoe, kayak, and tube. The recreational designation permits E. coli levels in the river (at any time) to be <235cfu/100ml.
[FIGURE 1 OMITTED]
Because fecal coliform bacteria levels have exceeded Georgia Water Quality Standards over the last ten years, portions of the lower Coosawat-tee River, Georgia, are listed as impaired by the state of Georgia and do not support its recreational-use designation. In EPAs 2008 assessment of the Coosawattee River, 30 km of the lower river were deemed impaired; various in-flowing water sources had the same classification, including Carter's Lake. The purpose of this study was to determine if agricultural land use is linked to elevated E. coli levels in the Coosawattee River. With this information, we then aimed at defining potential contamination sites by matching up E. coli data with current satellite imagery, aerial photography, and ground surveying.
MATERIALS AND METHODS
During the third week of June, 60 samples were collected from sites predetermined from topographic maps and satellite imagery. More specifically, the water samples were collected at 12 sites on the upper Coosawattee River (above Carter's Lake). 12 within Carter's Lake, and 36 sites on the lower Coosawattee River (Figure 1). Some of the sampling locations were selected based on the proximity to drainage inflow such as tributary entrances. Those samples collected at tributary entrances are noted in Table I and Figure 2.
Site Number E. coli cfu/100 ml Sampling location 1 200 ms 2 100 tr 3 233 ms 4 66 tr 5 100 ms 6 166 ms 7 0 tr 8 33 ms 9 0 tr 10 0 ms 11 0 tr 12 0 tr 13 ns ms 14 ns ms 15 0 ms 16 0 tr 17 0 tr 18 0 tr 19 0 tr 20 0 ms 21 0 tr 22 0 tr 23 o ms 24 0 ms 25 33 tr 26 700 tr 27 0 tr 28 33 ms 29 33 ms 30 ns ms 31 300 tr 32 67 ms 33 33 tr 34 267 tr 35 ns ms 36 ns ms 37 0 tr 38 67 tr 39 0 ms 40 ns ms 41 ns ms 42 33 tr 43 0 ms 44 567 tr 45 0 ms 46 767 tr 47 133 ms 48 833 tr 49 600 tr 50 167 ms 51 67 ms 52 133 tr 53 100 ms 54 33 ms 55 0 ms 56 933 tr 57 33 ms 58 33 ms 59 133 tr 60 33 ms
[FIGURE 2 OMITTED]
The water samples for E. coii analysis were collected under base-flow conditions for the Coosawattee River. The samples were prepared by methods outlined in the Environmental Protection Agency document for Method 1605 (7). Using this technique a water sample is filtered through a 0.45 in pore-size membrane filter. The filter is placed on ampicillin-dextrin agar with vancomycin (ADA-V) and incubated at 35[degrees]C ( 0.5[degrees]C) for 24 hours ( 2 hours). Temperature data loggers were placed in the incubators to ensure proper temperature was maintained during incubation. This membrane filtration method provides a direct count of E. coli in water. In addition, blank samples of sterilized deionized water were analyzed to confirm sterile procedures. The sample results can be found in Table I.
The software program Google Earth was used to correlate sample locations and E. coli results. First, we used the pinpoint tool to plot each site using the latitude and longitude coordinates recorded in the field. The E. coli results were then attached to each location. Samples that contained elevated levels of E. coli (< 235 cfu/l00ml) were highlighted as such. Second, we delineated the land use for each square half-mile along the entire length of the river. The assessments of land use were made using overlays of satellite imagery and current aerial photography. Five general categories for land use were identified: agriculture, residential, industrial, urban, forest. Within this study we did not distinguish between types of agricultural land uses. After completion, the land use was confirmed by field notes collected during the initial sample collection and by an additional site visit.
Using Google Earth, satellite/aerial imagery, and ground assessment, we determined that the land use of the upper Coosawattee River consisted of 69 percent residential, 15 percent industrial, 14 percent urban, and 2 percent agricultural; the lower Coosawattee River (south of Carter's Lake) is nearly 75 percent agricultural (Figure 1). Of the 52 conclusive samples collected, nearly 15 percent contained elevated levels of E. coli. Ail of the samples containing < 235 cfu/100 ml were collected in the lower portion of the Coosawattee and were found to be directly adjacent to agricultural land use (Figures 1 and 2).
The statistical probability of elevate E. coli levels being adjacent to agriculture land use was p=0.145; although minimal residential land use had the second highest probability (p=0.041) (Figure 3). The elevated samples of E. coli collected on the lower Coosawattee River ranged from 267-933 cfu/100 ml. The sample with the largest amount of E coli (933 cfu/100 ml) was collected at a tributary entrance called Crane Eater (Site 56).
[FIGURE 3 OMITTED]
Although it is not new information that land use practices impact the health of a river system, we believe that comparing elevated E. coli levels with agricultural areas adjacent to the Coosawattee River is a step closer to narrowing down potential sources of contamination. Because we did not want to pinpoint specific farms, farmers, or their associated land use practices, we used the term agriculture to include land that is used for both farming and the raising of livestock. However, we recognize that the primary agricultural land use along the Coosawattee River is apple orchards, cattle farming and poultry farming. As aforementioned, fifteen percent of our samples collected in the Coosawattee River show elevated levels of E. coll. All of these samples were found in the lower Coosawattee River adjacent to areas we delineated as agricultural. Moreover, the statistical probability we calculated indicate that there is a relationship between agriculture and elevated E. coli levels in this river system.
Several studies have examined the negative effect of livestock grazing on bacteria levels in water (8,9,10). It has been shown by Clemm (9) that fecal coliform can live in surface water up to six weeks and Van Donsel et al. (10) showed it can live in soil for two weeks. Therefore, a potential source of bacteria can enter with surface water runoff well after the animal has moved location. Tiedmann et al. (11) confirmed this with his research dealing with livestock management. Livestock kept in the Coosawattee River valley are mostly cattle and poultry. The fecal coliform counts for beef cattle, dairy cattle, layer hens, and broiler chickens range from 1,170,000 to 4,800,000 cfu per gram dry weight manure; the largest number relating to beef cattle (12). Therefore, the largest threat to the river may be a rainfall event immediately following the application of manure to a field. It is important to realize that the presence of rain can cause bacteria that are deposited on land to enter streams via runoff processes. The samples collected for this study occurred in a week with negligible (< 0.5 cm) rainfall. Therefore all samples were collected at a summer base flow for the Coosawattee River. Because precipitation did not occur, the data should be considered a minimal exceedance rate for E. coli. If surface runoff from rainfall can increase bacteria levels as suggested by Muirhead et al. (8), then the health of the Coosawattee may be even worse than we have presented in this paper.
Unlike the lower Coosawattee River, all of the samples analyzed for E. coli from the upper Coosawattee River were lower than the single-sample beach criterion set by USEPA standards. This may be the result of the Georgia Soil and Water Conservation Commission utilizing funding from the Clean Water Act to implement Best Management Practices (BMP) in 2007. The project entitled, The Upper Coosawattee 319 project, funded 35 landowners to protect water and soil quality on their farms through the installation of stackhouses, incinerators, stream crossings, winter feeders, heavy use areas, composters, and other available practices (14). As reported by Fulmer and Fowler (14), prior to the implementation of these strategies, the upper Coosawattee River was delineated as "not supporting" or "partially supporting" recreational use in the State's 2006 Section 303(d) and Section 305(b) Reports, Water Quality in Georgia. The funding for this project ended in March 2009. The water samples for this research were collected in June 2009.
This study has helped to narrow down the non-point source pollution to specific reaches of the Coosawattee River. This may be useful in reducing E. coli as well as fecal coliform levels in the lower Coosawattee River through the implementation of best management practices (BMP), as has been done in the upper reach. BMP describe efforts to decrease the amount of feces entering waterways while not greatly affecting the productivity of the property. Because cattle and swine livestock are less dominant along the Coosawattee River than poultry, the BMP may be focused on such production. Examples of appropriate courses of action may be as simple as off river watering sites for cattle and fencing off access to streams and rivers. The author also suggests a follow-up study to identify swimming-associated illnesses and correlate their incidents to time spent in the Coosawattee River when elevated levels of E. coli are found.
I would like to thank my student intern, Maggie Biggart, who helped to collect and organize data for this research project. I would also like to ac?knowledge the City of Rome Environmental Planner, Eric Lindberg, and the participants of the 2009 Georgia Paddle for contributing data. This paper was completed with help from the NSF GAIN grant.
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Dr. Tamie J. Jovanelly
Department of Physics, Astronomy, Geology Berry College
2277 Martha Berry Hwy Mount Berry, GA
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|Author:||Jovanelly, Tamie J.|
|Publication:||Georgia Journal of Science|
|Date:||Dec 22, 2011|
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