Trilinear diagrams display the relative concentrations of major ions dissolved in the water. Samples were taken quarterly to analyze for dissolved ions during seasonal low-flow conditions and during high-flow after a storm event. Analyses of the results indicate that there is very little change in the ratio between dissolved ions from low to high flow. Storm events merely dilute the total concentration of these ions in the water.

Water samples were collected quarterly at Spring Mill Lake, the junction of the streams flowing through the Pioneer Village, and six springs within the park. The samples were analyzed for major ions and trace metals. All of the water samples collected from Spring Mill State Park met the U.S. Environmental Protection Agency Federal primary drinking water standards for inorganic constituents except those collected at two sites in August 1999.