Physical Limnology of the Harris Wastewater Stabilization Ponds: July 1989 to October 1990

This report describes the first results of a study of waste stabilization ponds in the state of Minnesota. The study was started in July 1989 with support from the Legislative Commission on Minnesota Resources. Waste stabilization ponds are considered the most economical and efficient method of waste water treatment of small communities. This form of wastewater treatment relies upon the natural ability of a body of water to achieve self-purification. Self-purification involves the reduction of the bacterial content, satisfying the biochemical oxygen demands of the wastewater, stabilizing the organic content) and returning the dissolved oxygen content to desirable levels. Overall efficiency of waste stabilization ponds is a function of many interacting processes. The objective of the present study is to gain an understanding of the important factors and an insight into methods of stabilization pond management· that would ensure acceptable discharge standards. The purpose of this paper is to summarize observations and information gathered at the Harris ponds during the period of July 1989 through October 1990. The objective of the entire study is to gather enough meteorological,thermal, chemical, and biological information in order to gain an understanding of the processes at work in these ponds in order to develop a water quality model. It is hoped that this model and the understanding gained from it will be useful to improve the operation and performance of these ponds. In this paper predominantly hydrothermal (physical) features observed during the first year of the study are described and analyzed. This study is being conducted as a cooperative effort between the St. Anthony Falls Hydraulic Laboratory (SAFHL), University of Minnesota, Minneapolis, Minnesota, and the Minnesota Pollution Control Agency (MPCA), St. Paul, Minnesota.