Long term limnological measurements in Acton Lake, a southwest Ohio reservoir, and its inflow streams: 1992-2023

Long-term data were collected from Acton Lake and its inflow streams on a suite of physical, chemical and biological variables. The data are collected as part of long-term research investigating how Acton Lake, a eutrophic reservoir, responds to changes in ecosystem subsidies of detritus (sediments) and nutrients. Our data span 31 years, from 1992-2023, although for some parameters the data set spans a shorter time frame within this period. In three of Acton Lake’s inflow streams, collectively constituting ~86% of the lake’s watershed, we include data on hourly stream discharge, as well as concentrations of suspended sediments, ammonium-N, nitrate+nitrite-N, and soluble reactive phosphorus (P). Data on the concentrations of these constituents were collected at various time scales depending on stream discharge (usually every 6-8 hours during storms, every 1-3 days during baseflow). In Acton Lake, we collected data on several parameters from an “outflow” site, at the deepest part of the lake where the water column is usually thermally stratified in summer. Vertical profile data were collected for temperature, dissolved oxygen, photosynthetically active radiation (PAR), and chlorophyll. Depth profile data were collected at 0.5 or 1 m intervals (depending on depth and year), usually weekly from April or May until September or October. In addition, data for several parameters were obtained from “integrated samples” that collect water from the lake surface to the bottom of the euphotic zone (defined as the depth at which PAR equals 1% of surface PAR) with a tube or pump. Parameters for which integrated data are presented include chlorophyll; suspended solids; non-volatile suspended solids; particulate (seston) carbon, nitrogen and phosphorus; and total nitrogen and total phosphorus. We also collected Secchi depth data, using standard methods. Larval fish were collected in the top 1-3 meter stratum of the water column with a metered net to generate estimates of lake-wide larval fish density. Finally, zooplankton were collected by towing a net vertically through the water column; we present data on biomass and abundance of major zooplankton groups here. Several of these parameters are also reported for our “inflow” site. This site is in the shallow part of the lake, near the locations where inflowing streams enter the reservoir. Conditions at this site are considerably more variable than the “outflow” site. The “inflow” is relatively shallow (0.75-1.5m, depending on lake level), does not thermally stratify, and is typically more turbid than the “outflow” site, although water clarity and color varies greatly with storm influences. Larval fish were collected in the top 1-3 meter stratum of the water column with a metered net to generate estimates of lake-wide larval fish density. Finally, zooplankton were collected by towing a net vertically through the water column; we present data on biomass and abundance of major zooplankton groups here.