Harmful Pollutants

Sediment: Sediment that washes into rivers can cause many problems. The EPA lists this as the most common pollutant in lakes and streams/rivers. When the water is murky, plants are not be able to get enough sunlight, and will eventually die. It adversely affects animals that live here. The food chain becomes disrupted as the habitat for the smallest organisms changes. This has a ripple effect and can cause large declines in the fish population. Lastly, when enough sediment gets deposited, it can actually alter the flow of the river.

sediment can pollute a river

Where does all this sediment come from? It can be deposited naturally, but human activity causes much more. Building construction, new roads and logging which create exposed areas of soil are leading causes. With climate change causing more severe storms, the problem is magnified.

Phosphates and Nitrates: This category is also one of the main contributors to river pollution. Phosphates and Nitrates are food for algae. When algae takes over a river system, a number of negative things happen:

1) Light cannot reach the existing plant life in deeper water. This reduces oxygen levels in the water.

2) Decomposing algae also contributes to the lack of oxygen.

3) With less oxygen in the water, the sport fish like trout and salmon cannot survive. They are replaced by fish like carp and suckers.

phosphates and nitrates can kill fish in a river

What contributes to more phosphates and nitrates in the river? Fertilizers, both used by homeowners and golf courses add to the problem. So does agricultural runoff and sewage discharges.

As a homeowner, you can help by using more efficient fertilizers, and timing your application so heavy rains don’t wash much of it into the river. A vegetative buffer zone between your lawn and the river makes a big difference as well.

Road Salt: It seems more and more salt is being used nowadays on the roads. People are expecting better and safer driving conditions in bad weather. This is obviously important, but does come at a price. In a recent study by a research publication, 84% of streams measured in the U.S. had increased chloride concentrations (sodium chloride being the most common salt used on roadways). These higher levels can be unsafe for wildlife, and to humans, as the chloride can end up in well water. It may take most of the season for all the chloride to be flushed downstream from the winter salting.

road salt pollutes rivers like the farmington

To help combat this problem, towns and states are trying to be smarter about when to salt, and trying new formulas that may eventually cut back on the chloride problem. For now using a salt brine versus rock salt assures more stays on the road than bounces off when applied. Proper storage under cover and NOT on permeable surfaces is important as well.

Water Temperature Increase: As water temperature rises, the level of dissolved oxygen decreases. This can harm fish and other amphibians. Algae blooms grow more aggressively in warm water as well, further reducing oxygen levels.

Here on the Upper Farmington we do not have to worry so much about one of the leading contributors of rising water temperatures – industrial and power plants using it for cooling. There are however other factors. People clearing the forest down to the water’s edge lets more direct sunlight hit the river and streams which feed it, causing it to heat up. Also, during warm weather when rainwater runs over hot roads and parking lots, this water that enters streams can significantly raise the temperature.


Pesticides unfortunately pollute almost every stream in the United States, also getting into groundwater and contaminating wells. How does it happen? Leaching, runoff, and eroding soils containing these contaminants are leading causes. Many chemicals found in pesticides can stay in the soil for many years or even decades. Depending on the concentrations, they can be harmful to birds, reptiles, aquatic life and even humans. Pesticides have been used by people on their own property, as well as being popular for agricultural use. Technology has been developing pesticides that are somewhat friendlier to the environment, and people are also looking to alternative methods to stop weeds, invasives and insects rather than spraying a pesticide. Even with these advances though, overuse and improper application remain a big problem when pesticides are used.

spraying pesticides

Storm Water: Unfortunately climate change is causing more frequent severe weather events. When downpours happen, the storm water picks up dirt, bacteria, trash and chemicals which often find their way into the river. Snow melt is a culprit as well. As humans continue to develop land, water runs off paved areas and bare ground quicker than a forested area. If you own land that borders the Farmington or its tributaries, a well maintained vegetative buffer zone at the river’s edge can be very helpful in filtering some of these contaminants before they make it into the water.