Assembling Watershed Information

Ponds in Chester County have been built to fill a range of purposes and are valued in different ways by their owners. They vary in size and shape, and occur within watersheds of varying size, land use and topography. Not surprisingly, there is no single management "recipe". Instead, pond owners need to become knowledgeable about the range of management options available, and to recognize that management tools rarely affect just the target organism or environmental problem of interest; as will be repeatedly emphasized in this document, all major components of the pond ecosystem are interconnected by nutrient and energy flow. In deciding on a management plan, it is also important to concede that there are natural limits to feasible outcomes of management. With few exceptions, ponds in Chester County are nutrient rich, highly productive systems, and no amount of effort or expenditure is likely to change those fundamental attributes. More simply stated, pond owners should learn to love the color green.

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Watershed boundary (yellow line) superimposed on aerial photo of a pond in East Fallowfield Township showing pond and influent stream (in blue) within


Before considering any form of pond management, owners should obtain information about the watershed contributing water, nutrients, toxins and sediments to their pond. The watershed is that portion of the surrounding land that directs water and other materials toward the pond, either by surface runoff to the pond margin, runoff to an influent stream, or by groundwater inflow. An example is shown of a pond in East Bradford Township. The watershed boundary can be approximated by obtaining a topographic map of the area, and identifying the ridge tops. Topographic maps are available from the Chester County Planning Commission. In general, the larger the watershed relative to the size of the pond itself, the greater the likely negative impact of nutrient and sediment inputs, with consequent problems in pond management. Land use within the watershed is also an important determinant of pollutant inflow. Aerial photographs (available from the Chester County Planning Commission) can be used to visualize, for example, the extent of forested land, residential development, agriculture and pasture. Different types of land use contribute different amounts of nutrients and sediments to the receiving pond. For example, forested land tends to conserve nutrients and sediments, and is thus desirable, particularly near the pond itself. Tilled agricultural land, by contrast, experiences much greater runoff of soil and nutrients. See the Pond Ecology section for more information.