Loads and yields of sediment and water-quality constituents in Kentucky streams

Loads and yields of sediment and water-quality constituents were estimated for selected Kentucky streams. Streamflow, sediment, and water-quality information were collected at a network of 44 stream stations in Kentucky. Mean daily discharge was synthesized using the drainage-area ratio, regression analysis, or a combination of the two techniques. Streamflow was partitioned into total and base flow and used to estimate loads and yields for sediment and water-quality constituents through the use of ESTIMATOR and FLUX software. The relative magnitude of constituent transport to streams from ground- and surface-water sources was determined for 20 of the 44 stations. Mean annual total-flow yields for suspended solids (residue, nonfilterable) ranged from 0.4 to 365 tons per square mile (tons/mi). The smallest mean annual total-flow yield for suspended solids was determined at Clarks Run at Almo; the largest was determined at Eagle Creek at Glencoe. The aggregate median value of the mean annual total-flow yield for suspended solids was 112 tons/mi2. The analysis of trace-metal data indicates that the largest mean annual total-flow yield of cadmium-0.039 tons/mil—was determined at Clarks River at Almo. This yield is approximately 20 times greater than the aggregate median value of the mean annual total-flow yields (0.002 tons/mi2). Nine (45 percent) of the stations had mean annual total-flow yields equal to the aggregate minimum value (0.001 tons/mi2). The maximum total-flow yield of chromium (0.009 tons/mi2) was determined at Eagle Creek at Glencoe. Clarks River at Almo had the smallest estimated mean annual total- and base-flow yields for chromium (less than 0.001 tons/mi2). The aggregate median value of the mean annual total-flow yield for copper was 0.007 tons/mi2. Barren River at Bowling Green and Clarks River at Almo had the largest estimated mean annual total-flow yields for copper (0.017 tons/mi2). The aggregate median of the mean annual total-flow yield for lead was 0.021 tons/mi2. Barren River at Bowling Green had the largest mean annual total-flow yield of lead (0.04 tons/mi2). Three stations—Beech Fork at Maud, Red River at Clay City, and South Fork Kentucky River at Booneville—had an estimate of mean annual total-flow yields of lead equal to the aggregate minimum of 0.004 tons/mi2. Analysis of the nutrient data indicates that the largest mean annual total-flow yield of nitrite plus nitrate (11.8 tons/mi2) was estimated at South Elkhorn Creek near Midway. This yield is nearly 10 times the aggregate median value (1.3 tons/mi2). The minimum annual total-flow yield of nitrite plus nitrate (0.419 tons/mi2) was estimated at Middle Fork Kentucky River at Tallega. Salt River at Glensboro had the largest mean annual total-flow yield of ammonia and organic nitrogen (206 tons/mi2). This is nearly 400 times the aggregate median value of the mean annual total-flow yield of 0.57 tons/mi2. The phosphorus yield (total flow) was greatest at Clarks River at Almo with 3.4 tons/mi2. This phosphorus yield is nearly 30 times the aggregate median value of the mean annual total-flow yield of 0.12 tons/mi2. The smallest mean annual total-flow yield for phosphorus (0.036 tons/mi2) was estimated at South Fork Kentucky River at Booneville. North Fork Kentucky River at Jackson had the smallest mean annual total-flow yield of ammonia (0.004 tons/mi2). The aggregate median value of the mean annual total-flow yield for ammonia was 0.93 tons/mi2.