NONPARAMETRIC TREND ANALYSIS OF WATER-QUALITY DATA OF RIVERS IN KANSAS

Surface water quality data for 15 sampling stations in the Arkansas, V erdigris, Neosho, and Walnut river basins inside the state of Kansas w ere analyzed to detect trends (or lack of trends) in 17 major constitu ents by using four different non-parametric methods. The results show that concentrations of specific conductance, total dissolved solids, c alcium, total hardness, sodium, potassium, alkalinity, sulfate, chlori de, total phosphorus, ammonia plus organic nitrogen, and suspended sed iment generally have downward trends. Some of the downward trends are related to increases in discharge, while others could be caused by dec reases in pollution sources. Homogeneity tests show that both station- wide trends and basin-wide trends are non-homogeneous.