Although Delaware’s ocean beaches and well-flushed open waters of the Inland Bays have a deserved reputation for cleanliness and low bacterial counts, the same is not always true of tributaries of the bays. For example, the EPA lists Love Creek as impaired for recreational use because of high nutrients and bacteria. Problems with pollution and bacteria were highlighted in May, 2013 when DNREC closed shellfish beds in Love Creek because of high bacterial counts. The public safety issues posed by this bacterial contamination deserve more attention from the citizens of Sussex County and their elected representatives.
The University of Delaware Citizen Monitoring Program (www.citizen-monitoring.udel.edu) reports regularly on Total Enterococcus counts in Sussex County waters. Enterococci, bacteria found in feces of warm-blooded animals (birds, dogs, people), replaced fecal coliform bacteria as the federal standard for microbial water pollution and are considered a proxy for human pathogens. These organisms are naturally resistant to antibiotics and can directly cause urinary and blood-borne infections as well as wound complications. The EPA-recommended limit for Enterococci is a mean of 35 colony-forming units (CFU) per 100 milliliters of marine or brackish water calculated for several measurements over time. Counts above 35 CFU are cause to close areas for recreational activities. However swimming in water even at this level has been estimated to result in 19 cases of gastrointestinal sickness per 1,000 instances, so it is important to realize the EPA limit does not set a safe standard.
The Citizen Monitoring Program collected and analyzed between nine and 11 water samples between April and October each year from 2007 through 2013 for Love Creek where it flows under Route 24. The seasonal mean counts for Total Enterococcus were several-fold higher than the EPA limit every year. Moreover, the problem appears to be getting worse. A statistical analysis performed by us revealed a highly significant 2.5-fold increase in the seasonal means during the period 2007-13 with a probability approaching 99 percent confidence. This correlation was not explained on the basis of seasonal differences in precipitation, a factor often associated with increased bacterial counts.
Developments such as the proposed RV park along Love Creek are likely to worsen bacterial contamination. The scientific literature has established that increases in impervious surfaces beyond 10 percent of land surface are correlated with decreased water quality because of more rapid run-off. As reported by the Center for Inland Bays, the Rehoboth Bay watershed surpassed 10 percent impervious surface around 2007. We estimate the RV park is likely to have at least 30 percent impervious surface considering areas for RV pads, cabin roofs, roads, and parking. The developers could calculate this more precisely but did not provide the numbers.
A further implication is that potential recreational areas like the RV park, which is only one-half mile upstream of the Route 24 Love Creek bridge, may need to monitor bacteria and warn guests about the dangers of exposure to contaminated water that exceeds the EPA limit. Individuals especially at risk are those with immune systems that may be weakened by age (the very young and the old), those receiving therapy for conditions like rheumatoid arthritis, or anyone who has recently been diagnosed or treated for cancer.
As professional scientists with doctorates in medical microbiology and biology, we are deeply concerned. We wonder. Will the future motto of Sussex County be “Clean Water - Wave Good-bye!”? It needn’t be so. We have a choice.
Steve and Judy Britz
Lewes
