For water quality scientists there are many tools available for measuring pollution in the nation’s rivers, streams, lakes and ponds. These tools range from measuring chemical concentrations, such as for dissolved oxygen, alkalinity, phosphorus and nitrogen to biological toxicity test organisms such as daphnia, minnows and mollusks. In the last 5-10 years using domestic canines (dogs) to smell water pollution has become established in the science. The use of dogs to detect explosives, drugs and in locating persons by smell in search and rescue is well known. What is not well known is how well they can smell wastewater from human sources such as septage and sewage. Recently dogs have been used in urbanized areas of 11 states as part of a municipality’s program to locate and eliminate illegal or illicit discharges (IDDE). The municipal IDDE program is a requirement of the federal Clean Water Act. In Vermont DEC has supported a voluntary IDDE program statewide where it was not required.
Dogs can detect human wastewater in both the air and water with an incredible level of sensory perception. According to one source: a dog’s sense of smell may be as much as 100 times better than ours. A human nose has only three-square centimeters of olfactory membrane whereas some dog breeds, such as Bloodhounds, have as much as 150 square centimeters. Dogs also have forty times more scent processing cells in their brains than humans. A dog also has a phenomenal olfactory memory. A dog can remember smells long after being exposed to the original odor. Dogs also have an additional organ in their nasal cavity known as Jacobson’s organ. This organ’s function can best be described as a combination of taste and smell. Dogs can literally taste the air.1
Today in Vermont there are 22 known bacteria impaired water segments from nonpoint pollution sources (farms, streets, homes, wild animals) and 9 known point source/wastewater/combined sewer impaired water segments. In many of these segments locating the cause of the impairment can be extremely difficult and typically requires long term monitoring and investigation. Tracking down individual sources of bacterial pollution whether it is a leaky sewer pipe or a failed septic is not easy and requires skill and a certain degree of luck for the investigator.
Flower Brook in Pawlet is one of the 22 water segments considered impaired for bacteria, and has been known to be contaminated since 2008. Over the last 10 years the Poultney-Mettawee Natural Resources Conservation District (PMNRCD), VTDEC and the USEPA have collaborated on a variety of technical studies and monitoring to try and locate the nonpoint sources of bacteria in the watershed. The brook has a moderate level of bacterial contamination seasonally ranging approximately from 0-1000 col/100 ml. The current state standard is 235. In 2011 a USEPA study confirmed that human bacteria was one source of the contamination. Since 2008 PMNRCD has worked with various farms and landowners to reduce obvious nonpoint source runoff discharges to the brook and as a result the overall trend in water quality is improving.
This year VTDEC collaborated with the Center for Watershed Protection of Ellicott City, Maryland to conduct canine bacteria detection along Flower Brook. This study is a part of a larger effort to develop a national manual for rural communities to address bacterial contaminated waters2. This week Environmental Canine Services LLC of Turner Maine came to Flower Brook in Pawlet. In collaboration with the VTDEC contractor, Watershed Consulting Associates of Burlington, the team investigated 15-20 suspected sites based on earlier investigations. The dogs identified at least 8 positive sites which will now require further chemical monitoring and follow-up with landowners. Two of the eight sites had surfacing effluent or contaminated water. It took the dogs less than 15 seconds to identify a contaminated site once visited. The dogs were trained to either sit down or bark when human bacteria was detected.
One preliminary conclusion from this investigation is that Pawlet may have a number of sites where partially treated septage is being released to surface waters, either through groundwater or occasional surfacing of effluent. The dogs corroborated the 2011 USEPA results and provided more precise location information. The high frequency of positive human bacteria detects are a reason for concern. However, it is impossible to know at what E.coli concentration the positive canine detections correlate to, and therefore the dogs may be detecting human E.coli at very low levels. It is probable that the cumulative impact of a large number of small sources of poorly treated septage is contributing to the elevated levels in the brook rather than one or two large sources.
There are many Vermont communities like Pawlet that are (1) without a centralized wastewater system, (2) located on poor soils or soils with a shallow hardpan, and (3) have homes immediately abutting waterways or lakes and ponds. Any of these communities could have a very similar bacterial contamination problem as Flower Brook. Residential homes and camps that encircle lakes are a good example of where this could occur and also threaten the viability of the recreational resource. In many of these areas there is little or no monitoring for bacterial contamination. Canine bacteria detection could provide significant information on the present condition of private septic systems around recreational lakes and ponds as well as further our understanding of bacterial contamination in the 22 impaired state waters.
2Safe Waters, Healthy Waters: A Guide for Citizen Groups on Bacteria Monitoring in Urban Waters
Center for Watershed Protection, Ellicott City, MD. To be released in 2016.