Low-flow characteristics are presented at eleven gaging stations on the main stem of the Wisconsin, Fox, and Wolf Rivers in this report. The low-flow characteristics presented are the annual minimum 7-day mean flow below which the flow will fall on the average of once in 2 years (Q7, 2) and the annual minimum 7-day mean flow below which the flow will fall on the average of once in 10 years (Q7, I0).
To provide accurate and consistent low-flow characteristics for uniform evaluation of waste effluent, a long-term period of streamflow record was used for the analyses. The record selected for the study was 1915-75. This was found to be the most representative that included longterm streamflow conditions and various degrees of regulation by storage reservoirs.
The Q7, 10 discharge on the Wisconsin River ranged from lUO cubic feet per second at the Wisconsin River at Rainbow Lake near Lake Tomahawk gaging station to 2,790 cubic feet per second at the Wisconsin River at Muscoda gaging station. On the Fox-Wolf Rivers, the Q7, 10 ranged from 360 cubic feet per second at Fox River at Berlin to 950 cubic feet per second at Fox River at Rapide Croche dam near Wrightstown.
Low-flow characteristics that reflect unregulated and regulated conditions on the upper Wisconsin River were compared. This analysis showed no apparent difference in Q7, 10 discharge values due to regulation at the Wisconsin River at Merrill gaging station, although a more detailed study is warranted to fully evaluate the effect of storage.
The magnitude of the low-flow characteristics are in some instances affected by the period of record. These characteristics can vary as much as ±30 percent at some gaging stations depending on whether or not the severe drought of the 1930's was included in the analysis.
