Rodger F. Ferreira 1981 <p><span>Streamflow characteristics of drainage basins within the Fort Union </span><span>coal region of southeastern Montana were estimated to provide premining </span><span>data for evaluating the future effects of mining on the environment. </span><span>Estimated annual mean streamflow at 22 data-collection stations for </span><span>water years 1975-77 ranged from 0 to 887 cubic feet per second. These </span><span>estimates are based on miscellaneous-streamflow records at each station </span><span>and continuous-streamflow records from other stations in the study area. </span><span>Estimated mean annual streamflow for a 10-year period (water years 1968-</span><span>77) ranged from 0 to 572 cubic feet per second. These long-term estimates </span><span>were based on data from stations near the study area having continuous-</span><span>streamflow records. Estimated mean annual runoff in inches for selected </span><span>drainage basins within the study area showed no discernible pattern. </span><span>Many of the drainage basins had a mean annual runoff of less than 0.60 </span><span>inch; the maximum observed mean annual runoff was 4.45 inches. </span></p> application/pdf 10.3133/wri8161 en U.S. Geological Survey Mean annual streamflow of selected drainage basins in the coal area of southeastern Montana reports