This site is operated in cooperation with the Lower Sioux Indian Community

Precipitation is accurate to 0.01 inches except during freezing periods (about Dec. through early Apr.). The rain gage is unheated and uncovered. The precipitation data during freezing periods result from melting of snow (accumulated in the rain gage) during warm periods and do NOT represent actual precipitation. Precipitation totals during freezing periods may underestimate actual totals because the rain gage funnel may be full of snow (preventing further accumulation) or because snow in the funnel may sublimate instead of melt.

Water levels below land surface are accurate to 0.01 feet. Water levels above National American Vertical Datum of 1988 (sea level) are calculated by subtracting recorded water levels from the land surface elevation, which is accurate to ± 0.01 feet based on a differential GPS survey. Water-level differences are accurate to within 0.01 feet.

Water temperature is accurate to plus-or-minus 0.1°C, and differences in temperature are accurate to 0.1°C.