Bachmann and others conducted the first comprehensive study of water quality of Iowa lakes from Iowa State University (Bachmann et al., 1980). In 1980, a study of 115 significant publicly owned lakes was completed. States were required by the U.S. Environmental Protection Agency (USEPA) to conduct a survey of their public lakes in need of restoration and/or protection and to develop a priority ranking of the lakes for restoration projects. Significant publicly owned lakes are those lakes that are principally maintained for public use, contain a minimum surface area of 10 acres, and are capable of supporting fish stock of at least 200 pounds per acre. Information from this 1980 study has served as a basis for selecting lakes for restoration in Iowa.
Bachmann completed an additional survey in the early 1990s, and the information was used to revise the priority list of lakes for restoration (Bachmann et al., 1994). Each lake was monitored three times from May through August. Secchi depth, nutrients, and chlorophyll were measured.
The Iowa Department of Natural Resources Ambient Lake Water Quality Monitoring Program (2000-2015) has sampled 138 of Iowa’s principal recreational lakes and characterized each lake’s water quality. Because temporal variation in Iowa watersheds is great, this multi-year study yielded a stable and reliable assessment of Iowa lakes and lake watersheds. Each lake was sampled three times during each of the study years to assess seasonal and annual variability. Analyses from this project were used to create a powerful database that could be compared to previous decadal assessments of Iowa’s lakes (Bachmann et al., 1980; Bachmann et al., 1994; Downing et al., 2005).
The 2016 Ambient Lake Water Quality Monitoring Program continues this monitoring effort and provides the Iowa Department of Natural Resources with lake monitoring data, including biological, chemical, and limnological analyses on Iowa’s most important lakes. These monitoring data have many uses (e.g., lakes classification for restoration, water quality evaluation, monitoring), follow-up on similar surveys published in 1980 and 1994, and continue systematic monitoring performed from 2000-2014. The lake list and the analyte set for 2016 monitoring are provided in Appendices A and B.
Data are reported for each sampling date as well as seasonal averages for the current year and for previous years of monitoring when available. A summary data table of chemical and physical measurements for each lake is available from the Chemical/Physical Report page. Biological data are available from the Phytoplankton and Zooplankton pages. The Phytoplankton page contains one table including wet mass, taxonomic richness, and cyanobacteria cell counts and two graphs showing phytoplankton composition and annual percent cyanobacteria by genus. The Zooplankton page contains one table including dry mass, percent large suspension feeders, and taxonomic richness and one graph showing zooplankton composition.