Water Quality 101
How do our waterways get polluted?
What is a Watershed?
To understand how water becomes polluted, we need to understand the watershed concept. Simply put, a watershed is the area of land that drains to a particular waterbody. For example, the Genesee River watershed is 2,480 square miles in size and extends all the way to Pennsylvania. When it rains or when snow melts anywhere in the watershed, the water seeps into the ground or drains downslope through a network of channels and streams and ultimately reaches the Genesee River and Lake Ontario. If you’ve ever used a funnel, you get the idea of how a watershed works.
What is Stormwater and why is it important?
As our towns and cities developed, we constructed roads, parking lots, and driveways that disrupt the natural flow of water. When rain lands on these hard surfaces, it is not able to seep into the ground and instead becomes stormwater runoff. The runoff flows into the gutter, enters the stormdrain, and travels through a network of pipes to the nearest waterway. This network of gutters, drains, and pipes is known as the stormwater system and is intended to prevent flooding. In rural areas, the stormwater system is generally made up of ditches, rather than gutters and pipes.
What’s the difference between the stormwater system and the sewer system?
In most of the Lake Ontario watershed, the stormwater system is a separate system of pipes/ditches and is not part of the sanitary sewer system that transports sewage from our homes to the sewage treatment plant. This is a very important concept to understand. Water that enters the stormwater system is transported to the nearest waterway, and ultimately to Lake Ontario, without being treated at a sewage treatment plant.
The City of Rochester is an exception. In most areas of the City, the stormwater system and the sanitary system are a combined system. That is, both stormwater and sewage are transported through the same system of pipes and are treated at the sewage treatment plant.
How does stormwater affect water quality?
An unintended consequence of the stormwater system is that pollutants such as automotive fluids, fertilizers and pesticides, bacteria, sediments, litter, and pet waste are quickly and efficiently transported from parking lots, roads, and driveways to the nearest waterway. Stormwater pollution results from many of our everyday activities such as how we care for and maintain our cars, lawns, and pets. The good news is that these are sources of pollution that we can do something about.
When we think about water pollution, many of us think of industry and sewage treatment plants. While it is true that industry and sewage treatment plants can be a source of water pollution, these operations have made major improvements to their processes and have been regulated for many years. As a result, stormwater is now the most significant source of pollution to many of our local waterways.
What is the condition of our Local Waterways?
In general, water quality in the Genesee River, Lake Ontario, and our other local waterways is greatly improved because of major investments in infrastructure, government regulations, and other efforts. However, local water quality conditions are quite diverse and are a reflection of historic and present land uses in the associated drainage area.
How do we know what the water quality is in our local waterways?
New York State and many local municipalities and research institutions monitor and study local water quality conditions. The New York State Department of Environmental Conservation (DEC) publishes a “Priority Waterbodies List” that documents polluted waterways in the State. This list and many associated documents can be viewed on the DEC website.
What is the condition of Lake Ontario?
Lake Ontario is the most downstream of the five Great Lakes. As such it drains a watershed of almost 300,000 square miles across much of the north central United States and south central Canada. Excluding the drainage area of the other Great Lakes, the Lake Ontario watershed is 24,720 square miles in size. Water quality conditions in Lake Ontario are highly variable. Although water quality in the open waters of the Lake has greatly improved in recent decades, the near shore areas are still degraded. The Rochester Embayment (that area of Lake Ontario formed by the indentation of the Monroe County shoreline between Bogus Point in the town of Parma and Nine Mile Point in the town of Webster) has long been an area of concern for poor water quality.
Why is there algae at the beach?
Among the most visible water quality problems in the Embayment are the nuisance algae blooms at Ontario Beach and Durand Beach. An important nutrient supporting algae growth in Lake Ontario is phosphorus. This nutrient comes from a variety of sources including lawn and agricultural fertilizers, air pollution, pet waste, and leaky septic systems. When there is an excess of phosphorus, algae can grow and reproduce rapidly.
In addition to being unsightly, algae blooms create favorable conditions for bacteria to multiply. High bacteria levels are also associated with heavy rains. Stormwater can contain lots of bacteria that wash off of pavements and rooftops. When bacteria levels are high enough to cause health risks, the beaches are closed. For example, at Ontario Beach, Health Department scientists make decisions to open or close the beach based on the conditions at the beach on that day and what has happened in the days before that could impact the beach. They also collect water samples that tell them if there are bacteria present.
Is it safe to eat fish from local waters?
Fish consumption advisories are another significant water quality problem in Lake Ontario and other local waterways. Fish may contain dangerous chemicals in amounts considered too high by the New York State Department of Health (NYSDOH). People can consume these chemicals when eating the fish. The NYSDOH recommends that women of childbearing age and children under the age of 15 should not eat any fish from Lake Ontario and the waters that contain contaminated fish. Others should limit their fish consumption according to the specific advisory for that body of water.
What is the condition of the Genesee River?
Water quality in the Genesee River also varies greatly. For instance, the lower Genesee River watershed includes significant industrial and urban areas. Therefore, in this section of the river, one finds the types of water quality problems commonly associated with these land uses such as contaminated sediments and degraded aquatic life.
However, the Genesee River has benefited greatly from an innovative program in the 1970s to reduce the impact from the combined sewers that serve most of the City of Rochester. Prior to this program, the treatment capacity of the combined system was often exceeded during large rain storms. When this happened, an untreated combination of stormwater water and sewage would have to be discharged to the river. As a solution, large tunnels were constructed to store the combined stormwater and sewage during rain storms so that it can be treated later when capacity is available.
Residents often assume that the Genesee River is highly polluted because of its muddy appearance. However, much of this sediment load is naturally occurring and associated with the highly erodible soils in the watershed. Agriculture and construction activities in the watershed also contribute sediment.
The upper reaches of the Genesee River are not as impacted as the lower sections near Rochester and the sources of pollution there are generally associated with agricultural activities.
How clean are our local streams, ponds, and bays?
Many of our smaller streams, ponds, and bays have also shown significant improvements in water quality. In some cases, this has been the result of infrastructure improvements. For example, in the past, many towns and villages operated their own sewage treatment plants and discharged to local streams. However, because of the relatively small flow in these streams they were seriously impacted by these sewage discharges. Over the last few decades, many of these small treatment plants have been taken off line. Instead, sewage treatment is provided by larger regional facilities, such as the Van Lare Wastewater Treatment Plant which discharges into Lake Ontario. With these improvements, stormwater, construction, and agriculture are now the principal sources of pollution to our smaller waterways.
Acid Rain: Rain with a pH of less than 5.6; results from atmospheric moisture mixing with sulfur and nitrogen oxides emitted from the burning of fossil fuels; may cause damage to buildings, crops, forests, and aquatic life.
Algae: Any of various primitive, chiefly aquatic, one-celled or multi-cellular plants that lack true stems, roots, and leaves but usually contain chlorophyll. Included among the algae are kelps and other seaweeds, and the diatoms.
Figure 2. Algal growth
Atmospheric deposition: Particles from the atmosphere deposited on the earth's surface either in wet or dry form.
Combined Sewer: A sewer system by which both storm water and sanitary wastes are transported by the same pipe to a sewage treatment plant.
Erosion: The wearing away of land surfaces by wind or water. This process occurs naturally, but can be greatly intensified by land clearing activities. Erosion of soil along stream banks can cause streams and rivers to appear brown, and sometimes cause problems for fish and wildlife.
Figure 3. Stream Bank Erosion on Irondequoit Creek in Monroe County.
Eutrophication: A process of nutrient (mainly phosphorus and nitrogen) enrichment whereby water bodies gradually become more densely populated with vegetation and algae.
Figure 4. Eutrophication in Northrup Creek.
Phosphorus: Key nutrient influencing plant growth in lakes and streams. Soluble reactive phosphorus is the amount of phosphorus in solution that is available to plants. Total phosphorus includes the amount of phosphorus in solution (reactive) and in particulate form.
Runoff: Water from rain, snowmelt, or irrigation that flows over the ground and into water features. It can collect pollutants from the air and land and carry them into the receiving waters.
Sediment: Insoluble material suspended in water that consists mainly of particles derived from rocks, soil, and organic materials; a major nonpoint source pollutant that other pollutants may attach to.
Stormwater Runoff: Precipitation and snowmelt runoff from roadways, parking lots, and roof drains that is collected in gutters and drains; a major source of nonpoint source pollution to water bodies.
Watershed: All the land that drains to a specific stream, river, or lake.
Wetland: A landform (marshes, swamps, bogs, and fens) characterized by the presence of water, hydric soils, and hydrophytic vegetation. Often wetlands form the transition zones between upland and deep-water environments. Wetlands play a critical role in protecting water quality by filtering pollutants.