Chapter 2: Considerations for Building Small Impoundments
Robert D. Lusk, Michael J. Otto, J. Wesley Neal
Small impoundments are abundant in North America, largely due to rapid construction in the early to mid-1900s. In a 31-year period between 1934 and 1965, the number of small impoundments in the USA was reported to have increased 10,000% (Swingle 1970). This explosion in pond construction was largely due to the implementation of water conservation practices to raise the level of the water table during and following the Dust Bowl era (Hurt 1981). The Soil Conservation Service (now the Natural Resources Conservation Service [NRCS]; see Chapter 15) provided cost-share incentives to landowners who constructed small impoundments following specific guidelines.
As the drought and incentives faded with time, the demand for small private waters remained high and pond building continued. Often these ponds were constructed without adherence to guidelines. The mission was simply to rearrange some dirt, push up an embankment and dig a hole, usually to impound water for livestock or for irrigation purposes. Depth and slope were largely determined by terrain, and little consideration was given to the influence of pond design on habitat, water quality, or esthetics. The primary objective was to impound water at the least cost.
During the 1980s and 1990s, land use practices in the USA began to change. Sophisticated investors and developers wanted to increase land values by convincing people about the serenity of building homes and living next to water (see Section 1.5). City planners required adequate water supplies in the form of ponds that were adjacent to large buildings for fire protection. Therefore, suburbs grew around ponds and lakes. Also, many small farms were purchased by absentee landowners who wanted land and water for recreational purposes or wildlife habitat (e.g., Knutson et al. 2004). As these societal changes occurred, so did many of the considerations for building small impoundments.
Today, the demand for small waters continues to escalate, as does the diversity of reasons people wish to create small impoundments. For these developing reasons, pond building has become more complicated than simply “digging a hole.” A well-designed and well-built pond requires substantial planning and foresight. This chapter will examine the process of constructing a small impoundment and how to make informed decisions during each step of the process. The goal of this chapter is to provide a solid base of knowledge on pond construction considerations. Complex hydrodynamics and engineering discussions are not included. For more details on these concepts, see USDA NRCS (2000) or contact a civil engineer with NRCS or other agency.