The Aging of America's Reservoirs: In‐Reservoir and Downstream Physical Changes and Habitat Implications

Abstract

Reservoirs are important for various purposes including flood control, water supply, power generation, and recreation. The aging of America's reservoirs and progressive loss of water storage capacity resulting from ongoing sedimentation, coupled with increasing societal needs, will cause the social, economic, environmental, and political importance of reservoirs to continually increase. The short-and medium-term (<50 years) environmental consequences of reservoir construction and operation are well known and include an altered flow regime, lost connectivity (longitudinal, floodplain), an altered sediment regime, substrate compositional change, and downstream channel degradation. In general, reservoir-related changes have had adverse consequences for the natural ecosystem. Longer term (>50 years) environmental changes as reservoirs enter "old" age are less understood. Additional research is needed to help guide the future management of aging reservoir systems and support the difficult decisions that will have to be made. Important research directions include assessment of climate change effects on aging and determination of ecosystem response to ongoing aging and various management actions that may be taken with the intent of minimizing or reversing the physical effects of aging.

Internal phosphorus loading in Canadian fresh waters: a critical review and data analysis

“…Located in the Lake Winnipeg watershed and the Qu'Appelle subwatershed, Lake Diefenbaker is a prairie river valley reservoir fed primarily by flows from the South Saskatchewan River, the major source of external P loads (Hewlett et al 2015;North et al 2015). Considered "old" (Juracek 2015), this 49 year old reservoir serves as a sink for P, with the highest TP retention rates of the 28 largest lakes and reservoirs in the basin (Donald et al 2015). In Lake Diefenbaker, L gross from both anoxic (17 mg TP·m −2 ·day −1 ) and oxic (2 mg TP·m −2 ·day −1 ) sediment core incubations (Doig et al 2017) illustrate the importance of bottom-water oxygen conditions on P release from sediments.…”

Reservoir Sedimentation and Upstream Sediment Sources: Perspectives and Future Research Needs on Streambank and Gully Erosion

“…First consider the study by Juracek (2014) in which reservoir sedimentation rates were studied throughout Kansas. Results suggested considerable variability among reservoirs in the state.…”

The influence of a severe reservoir drawdown on springtime zooplankton and larval fish assemblages in Red Willow Reservoir, Nebraska

“…Therefore, extensive and prolonged drawdown for repair or replacement may become the norm, rather than the exception, in coming years (Juracek 2015). We believe that our findings may give reservoir managers some valuable insights into the abiotic and biotic changes they might expect, given the inevitability that additional dams will need to be repaired or replaced in the near future.…”

“…Therefore, extensive and prolonged drawdown for repair or replacement may soon become necessary (Juracek 2015), which could negatively affect reservoir ecosystems. Although numerous studies have examined the effects of extreme reservoir drawdown on water quality (Vernieu 1997;Furey et al 2004;Baldwin et al 2008;Olds et al 2011), fewer have examined the effects of an extreme drawdown on both abiotic and biotic characteristics (see Benejam et al 2008).…”