Who pooped in Granite Creek?

They say that in order to solve a problem, you must first admit that the problem exists. So, here it is: in Prescott, our local creeks and lakes have water quality problems. Some deny it, reasoning that talking about it might scare the tourists away. I say that is poppycock! We all need to be aware of these problems so that we can do something about them, for the good of the community and the people who reside here.

So let’s talk about water quality, specifically poor water quality. Our local creeks and lakes have water quality problems, primarily high levels of nutrients and bacteria. This summer, it was frequently reported by The Daily Courier that excess nutrients from upstream feed the notorius algal blooms downstream in the lakes. But we don’t hear as much about the bacteria levels in the creeks, that they commonly exceed state surface water quality standards. This is because bacteria is a ‘stinky’ issue, one that the Watershed Improvement Planning project is trying to address. One of the goals of this project is to identify the sources of bacteria and nutrient and design solutions to reduce their concentrations, thereby improving water quality.

We’ve been monitoring E. coli bacteria, present in the intestines of all warm-blooded animals, as an indicator that the water has been contaminated by fecal material. The E. coli found in our creeks is not necessarily the same strain that has caused foodborne illness from fast-food burgers or tainted spinach. E. coli isn’t even the stuff that is likely to make you sick if you happen to ingest it–the presence of E. coli simply indicates that there could be pathogens in the water that could make you sick. E. coli is a common standard used by drinking water utilities and other regulatory agencies because it indicates a level of risk is present if you come into contact or ingest the water. E.coli is also a conservative indicator, meaning that the risk of infection is pretty low.

We’ve also been working with a University of Arizona laboratory at the Maricopa Agricultural Center to try to determine the sources of the bacteria through DNA analysis of the bacteria Bacteroides which, like E.coli, is found in the intestines of warm-blooded animals. Unlike E. coli, Bacteroides is specific to its host, so the bacteria in the intestine of a domestic cat would have different genetic markers than the bacteria found in the intestine of a cow, human, or javelina. By studying Bacteroides DNA, we can know what the sources of fecal contamination in our watershed are so we can go about addressing them.

What has this preliminary data told us so far? Out of 23 samples collected within our watershed, 78% of them were positive for the human genetic marker. This means that our creeks have been contaminated by human fecal material in both the upper and lower watershed. But humans don’t go around leaving droppings wherever they roam, do they? In some cases, they do: a lack of adequate restroom facilities and poor sanitation practices by recreationists (swimmers, boaters, campers, hikers, etc.) can lead to higher bacterial levels in our creeks. Sewer overflows or septic system malfunctions are also sources of human fecal contamination, especially when they occur in or near a creek.

It is too soon to tell how much human fecal matter is contributing to the high bacteria levels in our creeks. Humans are just one likely source of fecal contamination of our waters. Wherever there are or have been animals, there will be droppings containing E. coli. Here in Prescott, that is pretty much everywhere—our forests, streets, parks, and backyards. Some common animal sources are 1) wildlife—deer, elk, raccoons, skunks, javelina, bobcats, etc.—in the forest and in town; 2) bird and waterfowl droppings on roofs and other surfaces, or directly into the stream or lake; 3) domestic pets such as dogs and cats; 4) livestock and poultry—horses, goats, chickens, turkeys, cattle. Pet waste and livestock manure can be managed so that it does not wash off site and into the surface water. Activities which attract wildlife can also be minimized.

While there will always be a certain amount of bacteria in surface waters, many of these sources can be controlled to minimize the risk to public health. Now that we’ve admitted our problem and are beginning to study it, we can do something about it. Doesn’t it feel good to have this ‘stinky’ issue out in the open?


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