Low-flow characteristics of Wisconsin streams at 397 sewage-treatment plants and 143 industrial plants in 30 river basins are presented in this report. The low-flow characteristics 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, 10 ).
The low-flow characteristics at most sewage-treatment and industrial plants (project stations) were determined by correlating base-flow measurements at the project stations with the concurrent daily mean flow at continuous-record gaging stations in the area. The Q7, 2 and Q7,10 discharges determined by a frequency analysis at the continuous-record gaging stations were used to estimate the Q7,2 and Q7,10 at the project stations. For some project stations the low-flow characteristics also were determined by frequency analysis at nearby continuous-record gaging stations or correlation analysis at nearby low-flow partial-record stations. The Q7, 2 values ranged from 0 to 3,770 ft3/s and Q7, 10 values ranged from 2,790 ft3/s.
The accuracy of the estimated low-flow characteristics is evaluated according to the type and amount of data used to determine the low-flow characteristics. The accuracy determined by the standard error of estimate for the 10-year low flow (SE7, 10)) ranged from an average of 18 percent at continuous-record gaging stations to an average of h6 percent when only three base-flow measurements were available.
