Hydrology of the Price River basin, Utah, with emphasis on selected coal-field areas

Data obtained during a hydrologic study of the Price River basin, Utah, are used to describe seasonal variations of flow of springs, relation between ground water and surface water, hydraulic properties of the ground-water reservoir, ground-water recharge and discharge, flood characteristics of streams, mineralogic composition and depositional rates of sediments, nutrient and inorganic loading in streams and Scofield Reservoir, and water budgets for selected basins. Additional study and monitoring are needed to detect possible hydrologic changes caused by coal mining.

Much of the ground-water discharge from the Star Point Sandstone in the Mesaverde Group in the Wasatch Plateau occurs along faults. In the Book Cliffs, where faulting is less extensive, most of the ground-water discharge is from the Flagstaff Limestone. The Flagstaff Limestone is greatly diffusive, has a small storage coefficient, and contains water which is perched.

Springs issuing from the Star Point Sandstone in the Mud Creek drainage (Wasatch Plateau) had recession indexes greater than 365 days per log cycle. Springs issuing at higher altitudes from the Colton Formation and the Flagstaff Limestone in the Soldier Creek area (Book Cliffs) have great seasonal variability, with recession indexes ranging from 24 to 115 days per log cycle. Estimated transmissivities in the Soldier Creek area ranged from 0.003 foot squared per day in the lower part of the Castlegate Sandstone to 0.07 foot squared per day in the Price River Formation.

Seepage from the Star Point Sandstone is the major contributor to base flow of the stream in Eccles Canyon (Wasatch Plateau). Gains of as much as 230 gallons per minute occurred near a fault zone which crosses Eccles Canyon at the junction with South Fork Canyon.

The potentiometric surface of water in the Blackhawk Formation in the Wasatch Plateau (Mud Creek drainage) and the Book Cliffs (Soldier Creek area) generally is above the coal zones, and dewatering will be necessary in most places during mining. The total reported mine discharge during 1980 was about 2,800 acre-feet.

During the 1980 water year, ground-water discharge from the Flagstaff Limestone contributed about 4,400 acre-feet, or 41 percent of the combined streamflow of Coal, Soldier, and Dugout Creeks. Discharge from the Blackhawk and other formations contributed about 2,200 acre-feet, or 21 percent of the streamflow. The recharge to a 4,020-acre outcrop of the Flagstaff Limestone in the Soldier Creek area was determined from measurements of the discharge of springs and seepage gains in streams. The estimated recharge was 2 inches per year, or 12 percent of the April 1 snowpack, or 9 percent of the precipitation during 1980.

Benthic-diversity indexes at streams in the Book Cliffs and Wasatch Plateau are related to the size of the bed material. The Shannon-Weiner diversity index for five sites in the Mud Creek drainage ranged from 1.57 to 4.20 during four sampling periods in 1979-80. In the Soldier Creek drainage, the diversity index for four sampling sites ranged from 0.8 to 2.3 during three sampling periods in 1979-80.

Sediment deposition in Scofield Reservoir during 1943-79 was estimated to be 3,000 acre-feet but most of the coal deposition in the reservoir occurred prior to about 1950. An anaerobic zone develops in the reservoir during the summer, but the water in the reservoir completely mixes during late summer or early fall.