Several canals in southern Florida run from Lake Okeechobee through the Everglades Agricultural Area (EAA) and feed water to the northern Everglades. Agricultural and water-management practices affect the water quality of these canals. Fertilizers added in the EAA flow into the canals and are transported to treatment areas which remove much of the phosphorous in the water, but are not as effective in removing dissolved sulfate. Elevated sulfate concentrations, found downstream in the Water Conservation Areas in the northern Everglades, can stimulate sulfur-reducing bacteria which can also convert inorganic mercury to methyl mercury, a bioaccumulative neurotoxin. Chemistry data at 25 canal sites in southern Florida were sampled for water properties (temperature, pH, specific conductance), sulfur isotopes, major anions and cations, nutrients (including ammonium and orthophosphate), and trace metals. Data collection began in 1996 with a small subset of sites, and has continued through 2019. Funding for this data collection was provided by the USGS Priority Ecosystems Studies Program for South Florida (Nick Aumen, Program Executive).