Gauge Record Hydrologic Statistics: Indicators for Lake Classification

Surface water structures and associated active stage management and water use have altered many lakes. Assessing the degree of alteration requires an indicator of hydrologic regime as a first step. Water level regime is an organizing principal of soil morphology and the structure and function of wetland vegetative communities in lakes, marshes, ponds, and wet prairies. Although lake classifications have included a wide variety of physical and biological indicators for various purposes, none is based on hydrologic statistics of water level regimes beyond frequency parameters and simple stage range. Statistical measures of exceedance and level change were derived from the gauge record for a sample of 135 lakes. These measures were used in a principal component analysis to derive independent indicators for lake classification. The first two principal components accounted for 88% of the variance of six original variables and identified two indicators of hydrologic regimes: stage range (50%) and stage rise/fal...