Damming a stream inserts a lentic system (an impoundment or reservoir) into a lotic system, changing downstream hydrological, biogeochemical, and ecological processes. One such ecological effect of damming is to create a resource subsidy of easily captured and consumed zooplankton, which are preyed upon by filter-feeders and visual predators.  The data included here were used to predict the density of lentic zooplankton subsidizing downstream habitats with water quality parameters as an alternative to microscopy.  We also used this data to detect three different water quality regimes (high conductivity, high-CDOM, and a remainder) that are associated with differences in the density of zooplankton.  This dataset is contained in two parts, both of which are focused on zooplankton density in the effluent of a series of tributary-impoundment reservoirs: 1) zooplankton density for a single summer season with water quality parameters and 2) zooplankton density for a series of three summers without water quality parameters.

The methods of data collection are given in more detail within the accompanying peer-reviewed article.  We sampled the effluent (outlet) of four different reservoirs on a weekly basis during the summer.  Zooplankton samples were obtained with a 63-micron zooplankton net.  Concurrent environmental (water quality) data was obtained using a multi-parameter sonde and hand-held instruments.  Most water-quality parameters were measured in the field but some were measured in the lab shortly after sampling.  The "zooplankton density" found in this dataset has been standardized to count/L.