This report presents estimated annual and monthly water budgets for Lake Wingra and the adjacent wetland area for January 1972 through September 1972. Annually, inputs from precipitation, surface runoff, and groundwater inflow are approximately equal (31, 34, and 35 percent, respectively). Outputs include outflow from the lake into Murphy Creek (70 percent), evapotranspiration from the lake and wetland (26 percent), and ground-water outflow (4 percent).
The inputs and outputs vary seasonally. In months when snowmelt occurs, surface runoff is a major input (56 percent in March; 46 percent in April). In fall and winter ground-water inflow is a major input (57 percent in November). Precipitation comprises 41 percent of the input in August but only 18 percent in January. Lake outflow is the major output except from July through September. Combined evaporation and evapotranspiration is a major output in summer (45 to 58 percent) but minor in winter (less than 13 percent). Ground-water outflow is a small part of the budget each month, ranging from 2 percent in March and April to a maximum of 7 percent in September.
The water budget is based on field data collected from January 1972 through June 1973, and on fragmentary data and estimates for July 1973 through September 1977. The budget terms differ from those published by Oakes, Hendrickson, and Zuehls (1975, table 10) because springflow has been included in total ground-water inflow and estimated on a monthly basis in this report. Previously only annual estimates were provided.
