Dr. Michael Twiss is a professor of biology at Clarkson University, director of the Great Rivers Center and serves on the editorial board of Frontiers in Aquatic Biology. His research focuses on the Laurentian Great Lakes and St. Lawrence River ecosystems, and involves work on both research vessels and in the laboratory using organisms isolated from these environments..
Rivers are the defining features in the St. Lawrence County landscape. The county is named after the 13th largest river in the world that drains the North American Great Lakes, the source of 20% of the fresh surface water on Earth. This globally significant river has an annual average discharge of 6,800 cubic meters per second – that will fill an Olympic-sized swimming pool in less than 0.4 seconds.
The St. Lawrence flows past the northern boundary of the State and it is the largest single fluvial source of freshwater to the North Atlantic Ocean. In comparison, the Hudson River has an annual average discharge of about 600 m3 per second. Adding to the flow of the St. Lawrence River are four major tributary rivers that originate high in the Adirondack State Park and flow north through the county to the St. Lawrence: the Oswegatchie, Grasse, Raquette and St. Regis.
Despite the pristine appearance of these rivers, three issues pose a potential threat to humans and our ability to manage those ecosystems properly: mercury contamination, the invasive plant Eurasian watermilfoil, and fecal contamination of source water.
In collaboration with scientists from the University of Ottawa and the St. Lawrence River Institute for Environmental Sciences, I led a sampling expedition to the St. Lawrence River below the Moses-Saunders power dam, where three tributaries (the Grasse, Raquette, and St. Regis) enter into the St. Lawrence River within a span of only 6 miles. The St. Lawrence River has very low mercury concentrations, despite draining a very industrialized region (the US mid-west states and southern Ontario), but the tributaries had elevated concentrations of mercury of which almost one half was in the form of methylmercury, the neurotoxin that bioaccumulates in fish meat.
This observation supports our current understanding of how the Adirondacks, with essentially no heavy industry within the park boundary, are affected by fossil fuel electric generation many miles away. In this case, the combustion of coal has polluted the Adirondacks with both mercury and sulfate. Great strides have been made to reduce air pollution emissions and there are signs that once acidic lakes are recovering from this long-range onslaught. However, the legacy of decades of poor air pollution control has left these contaminants in the landscape.
Unfortunately, our damming of rivers to produce electricity without air pollution has exacerbated the mobilization of mercury into methylmercury since sulfur reducing bacteria, the microorganisms that methylate mercury so they can detoxify it when it accumulates in their cells, thrive in low oxygen conditions found in the organic rich sediments in river reservoirs. Controlling the threat of methyl mercury requires educating those who catch and consume the fish. Unfortunately, most eagles, mink, and otters are illiterate.
Eurasian watermilfoil, Myriophyllum spicatum, has been in New York State since 1949. Over the past 65 years it has spread to almost every freshwater in New York. St. Lawrence County was the last county for it to reach in 2011. Norwood Lake is a reservoir on the Raquette River in the Village of Norwood that has been invaded by this nonindigenous plant. With the assistance of my limnology (freshwater oceanography) class we investigated the situation in Norwood Lake at the invitation of the Norwood mayor, Jim McFadden.
The class determined that due to light, nutrient and substrate conditions, Eurasian milfoil was capable of spreading to over 80% of the lake surface area and grow down to a depth of 10 feet. Several management options were considered and most were dismissed since they were deemed unsustainable. For example, physically removing the plants can cause plants to break and fragments will then seed other parts of the lake, in addition to enhancing the spread downstream. Adding chemical herbicides is not ideal in a river for the obvious reason of competing against flow. Removal by hand (scuba divers) although reducing breakage is very expensive and is never fully effective.
The students recommended to the Village of Norwood to adopt an integrated approach wherein some sections would be allowed to be invaded so that the rates of Eurasian milfoil could be determined, some areas (near the bathing beach and docks) could have the plants removed by hand or covered with rubber mats to prevent growth, the indigenous milfoil weevil (Euhrychiopsis lecontei) could be raised and released to help stress the Eurasian milfoil, and periodically the Village could request the local power producer (Brookfield Power) to reduce the water level during the depth of winter so that the lake bottom would be exposed to harsh killing cold. The study sites could be used to follow the effectiveness of the integrated approach. The Village decided to spend money on hand removal only.
Fecal Coliform Contamination
Upstream from the Village of Norwood is the Village of Potsdam where drinking water is drawn from the Raquette River. Several years ago, an investigation with my colleague Professor Tom Langen showed that fecal coliform bacteria increased to levels that exceeded New York State Department of Health guidelines as water travelled down the St. Regis River from the Adirondack Park to the St. Lawrence River. Those results were published in 2006 in theAdirondack Journal of Environmental Studies.
Fecal coliform bacteria, that originate in animal guts and correlate highly with pathogenic bacteria, were shown to be closely associated with land use. Lowest fecal coliform counts were encountered in forested landscapes and the greater the land use was associated with farming the greater the fecal coliform concentrations encountered. Since the Village of Potsdam in surrounded by farms the Clarkson University limnology class in November 2014 decided to take a closer look.
In one afternoon, students sampled water quality at 14 sites along the river – from 10 miles upstream to the end of the river downstream of the village. Nearshore sites were sampled from the river edge, mid channel locations were sampled from bridges and tributaries were sampled as well. Exceedingly high fecal coliform concentrations were found in tributaries that drained farmland. These high concentrations were also measured at sites along the shoreline as water flowed to the village, on the same side where the village draws its drinking water for treatment.
Because the village periodically treats the water with high levels of chloring to kill the bacteria, it often has high trihalomethane concentrations in the finished water. Trihalomethanes can be carcinogenic with prolonged elevated exposures. The limnology class concluded that the cost of fecal contamination present in small tributaries was being borne by the Village of Potsdam taxpayers (water treatment is not free) and drinking water consumers (there is a metabolic cost to consume trihalomethanes).
In summary, the three issues mentioned above represent a range in our ability to manage – from wide scale mercury contamination across the Adirondacks that gets channeled into rivers, to invasive aquatic plants that require difficult albeit sustainable solutions for management since eradication is highly unlikely, to how readily manageable land use can affect our drinking water quality. Our local rivers can tell us about our environment, and in turn we should consider how we can understand, support and protect them.