Natural History. Stewardship. Sustainablility.
INTESTINAL BACTERIA IN NE HARTLEY WATERS
WATER COLOR IS DUE TO WHAT?
The varying light yellow to brownish orange color of the water in Hartley Pond and Tischer Creek is not due to dissolved iron, nor due to feacal contamination, but is a common and natural color due to other and harmless dissolved organic materials from decaying algae and aquatic plants. Along the Northshore of Lake Superior the root beer color of the streams is due to flowage through large areas of bogs upstream that are concentrated sources of those organic materials. The iridescent oily looking film on non-moving (stagnant) water, and the orange cottony material that may accumulate in the water under the film is suspended oxidized iron secreted by iron bacteria which get their life energy by oxidizing the invisible unoxidized iron dissolved in the water. The iron and the bacteria and orange diatom algae accumulate when the stagnant water is not carrying the material downstream.
TESTING WATERS NOW IS EASIER & QUICKER
A recent study showed that counts done by people “at home” using recently developed easy to use test kits, vary somewhat, and the counts done by labs like the Western Lake Superior Sanitary District (WLSSD in Duluth) also vary somewhat, even though they may be from the same sample of water. The small variations in the very low count values in the chart probably are due to these kinds of variations in the results. But the degree of accuracy is still sufficient to be useful. The highest count values are certainly real; they are confirmed by both labs and “at home” counts from the same water samples.
LAKE SUPERIOR RESULTS
A recent Minnesota Sea Grant College Program study along Lake Superior shores also show increases in E. coli after rain events. That study also showed strong evidence that after the bacteria enter the water, at least some of them remain alive thru the winter and take up home in the biofilm that develops naturally on the surfaces of attached algae, stones, sand grains, bedrock, and other surfaces that are in the water. When water is agitated like in streams raised by a significant rain, many E. coli bacteria enter the water from the biofilms, raising the bacterial content of the water. It is usually unknown how many of the bacteria in any specific situation that enter the water from and bird droppings, human, and other mammals are pathogenic to humans. It seems very likely that the bacteria released from biofilms into the water are not pathogenic but are harmless bacteria naturalized to their habitat.
IS HARTLEY POND & TISCHER CREEK SAFE?
We can’t predict when E. coli values in the pond and the creek will exceed safe swimming standards and by how much from the amount of precipitation. We also don’t know how many have come directly from the droppings and how many harmless ones come from biofilms. None-the-less, E. coli tests can be useful to tell us possible sources of the intestinal bacteria and the possible presence of pathogenic bacteria, when done frequently enough to see associations with precipitation and water use. The closure of beaches in times of high coliforms is still a prudent procedure until we learn more. People have gotten severe health problems from high-coliform waters. Better safe than sorry!
As for myself, I wash my hands after testing our waters so I don’t contaminate my lunch and snacks!