Taking Care of Our Watershed

The activities included in this lesson focus on various sources of pollution and how pollution can affect our daily lives. This lesson will also cover pollution prevention, and the role of industry in the pollution of fresh water. First we introduce pollution types and some terminology. Included as well will be groundwater pollution, which can result in contamination of drinking water, the role of wetlands as water filters, and the wastewater treatment process.

Many families, especially in the Catskill Mountains, use groundwater from a well or a spring to supply their homes with water. Because groundwater plays a large role in the water cycle and is relied upon by many homes, the necessity for protecting our groundwater is quite obvious. When water enters the ground, gravity moves it downward until an impervious layer stops it. The soil on top of this bedrock layer must become saturated first, before the soil above it can become saturated. The area of saturated soil (where all pores spaces between the soil are filled with water) is called the zone of saturation. The upper boundary of the zone of saturation is called the water table. The soil above the water table may be moist, but it is not saturated. The level of the water table fluctuates, especially during droughts and rainstorms. When a well "dries up" during the summer, this indicates the water table has dropped below the bottom of the well.

Groundwater pollution is next to impossible to clean up in part because you cannot clearly see how far the plume (the dispersing pollution) has traveled, and at what rate it is moving. Remember, groundwater flows but not always downhill. Landfills, underground waste dumps, leaky septic tanks, and underground storage tanks (e.g., gasoline, oil) are the major sources of contamination, and the only real solution is prevention.

Point vs. Non-point Source Pollution

Pollution is considered to be either point source or non-point source pollution. Point source pollution is defined as pollution that comes directly from a known source, like the end of a discharge or drainage pipe. Non-point source pollution is defined as pollution without a specific, single source; for example, acid rain results from many different pollution sources throughout the world. Storm drains are considered non-point sources because they collect runoff from many places, such as parking lots that are polluted by many different cars (sources). Point and non-point source pollution are also terms used to classify air pollution. Smokestacks are examples of point sources, while cattle herds, a source of the methane gas polluting our atmosphere, are considered a non-point source of air pollution.

Pollution at Home

A typical home in the Catskill Mountains (or elsewhere) can experience many types of pollution, and contribute to pollution in many ways people never realize. If your drinking water has high levels of various chemicals, you may be need to filter your water. Your daily activities can pollute your own water or that of other people who live in your watershed! Using excess fertilizer, car fuel leaks, washing your car, storing rusty metal outside, and other sources contribute to groundwater pollution and may eventually contribute to drinking water pollution. In villages and urban areas, these contaminants wash into storm drains, which eventually lead to a river or stream, usually without any form of treatment.

Wetlands

One way pollutants can be removed from a stream or river is by wetlands. Wetlands provide a service called leaching, a process that removes most or all of the impurities, nutrients, and silt or sediment. Wetlands are sometimes used as a primary treatment for wastewater before it even begins the normal treatment process. Wetlands function in many other amazing ways as well. Flood control may be the biggest asset of wetlands, because they can hold water even if the entire ground is saturated. The runoff from floods can be absorbed, as if by a sponge. Wetlands also provide habitat for some of the most interesting wildlife on the planet, especially migratory birds. The many species of flora in any wetland allow oxygen and nutrients to mix with the surrounding water. The New York City Department of Environmental Protection (NYCDEP) now focuses much attention on the importance of wetlands. Wetland field trips can be arranged through Beth Gelber of NYCDEP, whose contact information is provided in the appended material.

Forestry

The role of forestry in pollution prevention is an important one. Logging is often viewed by the general public as harmful to the logged area, and to the environment as a whole, but this is not always true. There are times when clear-cutting (logging every tree within a specific area) is necessary to make way for man-made structures, or for other land uses. Clear-cutting is one of the worst things that could possibly be done to a forest. It not only ruins the forest ecosystem, but if the land is sloped, it can cause erosion and aesthetic problems. Responsible loggers take necessary measures to prevent environmental degradation by constructing logging roads where the gradient is not very steep, and by reusing old logging roads when possible. Under those conditions, selective tree cuttings can be healthy for forests.

Fires are often considered good forestry practices because wild fires generally do not burn long enough or hot enough to kill trees before they run out of fuel. Burning the understory gives the larger trees and many smaller plants more room to grow. Certain fires are started on purpose (a controlled burn) and some naturally-occurring wild fires are left to burn themselves out if they do not spread out of control. The fire simply wipes out the smaller, often invasive understory that can sometimes prevent the formation of the ideal forest.

Agriculture

Much like logging, if agricultural practices are not kept in check, the repercussions on the environment are profound. Farmers, both crop and dairy, can completely destroy a local stream if proper farming practices are not used. With most farms being built in proximity to a watercourse, pollution can enter the stream easily from a number of sources. Fertilizers and pesticides that are applied in excess or just prior to a rainfall will wash into the stream. Oils and fuels from machinery that leak or spill will soak into the ground and wind up in the stream and groundwater. Runoff containing animal wastes from barnyards and pastures will flow untreated into a nearby stream. Now more farmers are adopting new technologies to meet recent state and federal pollution standards, but some farmers cannot afford the technology. They believe the incentive is not great enough for them to change farming practices which likely have been used for generations. Farmers must be willing to cooperate with the new standards being set; and state and federal government must understand that the farmers require money and incentives to undertake these improvements.

Wastewater Treatment

Wastewater treatment plays a large role in pollution prevention. Ideally, this means taking polluted water and making it clean. Wastewater enters a treatment plant through a screen that filters out all of the large debris, like pebbles, rocks, seeds, etc. These settle out in the grit chamber, before the water enters the primary settling tank, where the solids, or sludge, settle to the bottom. The wastewater is passed on to the aeration tank, where oxygen and bacteria are added. After aeration, the wastewater moves to the clarifier for secondary settling. After the sludge has settled, it is pumped to the sludge digester, and disposed of after by first drying it out and stabilizing it. Then it is deposited in landfills, composted, or used as fertilizer. The water from the clarifier has now been treated and is ready to be used once again or discharged into a nearby water body.

Wastewater from sanitary sewers and from sewers that gather stormwater are often linked. Many municipalities, during large storms, experience what is called a Combined Sewer Overflow (CSO). A CSO only occurs when there is a large storm, with a great deal of runoff, which combines with the city's sewage, resulting in too much wastewater for the treatment plant to handle. Most wastewater treatment facilities are near bodies of water, so when overflows occur, the water source takes a direct hit of untreated wastewater. The best solution to this problem would be to separate the stormwater drains from the sanitary sewers. Stormwater becomes polluted by many sources, most of which could be reduced in any household. Some ways are: 1) Use less fertilizer and pesticides. 2) Do not leave hillslope soil exposed. 3) Do not store rusty metal outside. 4) Maintain your car. 5) Do not use lead-based paint. 6) Do not litter.

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