Semi-quantitative microcystin concentration measured in surface water samples collected by the Citizen-Led Environmental Observatory (CLEO) from multiple nearshore sites in Lake Lillinonah, Connecticut, USA, 2015-2018

Included in this data package are cyanobacterial toxin data from the Citizen-Led Environmental Observatory (CLEO), a volunteer water quality monitoring program run by Friends of the Lake (FOTL, friendsofthelake.org) and Fairfield University at Lake Lillinonah, Connecticut, USA. The program has been operational since 2008 (toxin data available form 2015-2018). Trained volunteer monitors collect routine surface water samples from multiple nearshore sites twice a month from Memorial Day through Labor Day. In addition, spot samples are taken whenever a significant algae bloom is present at the collection site. These samples are analyzed for microcystin concentrations. Routine water samples are also analyzed for levels of the total nitrogen and phosphorus concentrations. Additionally, CLEO volunteers collect data on water temperature, Secchi disk depth, water color, presence of floating woody debris, recreation potential, trash, particle type and surface scum every 1-3 days during the same period. These data are available in EDI packages EDI567 (general water quality) and EDI568 (nutrients).