Flow characteristics of streams that drain the Fort Apache and San Carlos Indian reservations, east-central Arizona, 1930-86

Streamflow characteristics of the Salt River and Gila River basins in the Fort Apache and San Carlos Indian Reservations, were studied in response to pending adjudication of water resources in those basins. Statistical summaries were compiled for 28 streamflow-gaging stations in and near the reservation. Mean annual streamflow for 1930-86 was computed for stations with complete records for the period; for those stations with records that did not completely cover the 1930-86 period, record extension techniques were used. Mean annual streamflow for ungaged sites on streams with gaging stations was estimated by interpolation between data points using drainage-area ratios. Two regional-regression equations were derived to estimate mean annual streamflow at sites on ungaged natural streams. The standard error of the regression for estimation of mean annual flow for sites in the Salt River basin is -37 to +59%. The standard error of the regression for estimation of mean annual flow for sites in the Gila River basins is -18 to +21%. (USGS)