Hydrology and Nutrient Flow


Red Butte Creek is a perennial third-order stream without upstream regulation or diversion until flow is collected in the reservoir located near the base of the canyon. The stream has created a narrow-based canyon with sides rising abruptly at an average slope of about 35 degrees to the north and about 40 degrees to the south. Immediately upstream of the reservoir is a U.S. Geological Survey Hydrologic Bench Mark Station. This gaging station has been maintained by the U.S. Geological Survey since October 1963. Prior to that, the Corps of Engineers, U.S. Army, recorded monthly dishcarge at this location beginning in January 1942.

The average monthly discharge (1964-88) is 0.133 m3/sec (~4.7 ft3/sec) as it enters the reservoir at 1646 m (5400 ft) elevation (U.S. Geological Survey Records). The stream flow exhibits a straightforward annual pattern, characteristic of this geographic region - high spring flows driven by snowmelt followed by very much reduced flows derived from groundwater throughout the remainder of the year (Figure 6). Spring melt flow, which is typically an order of magnitude greater than other periods of the year, peaks in May and persists for 6 - 8 weeks. The average monthly stream flow rate during May is 0.416 m3/sec (14.7 ft3/sec). By September, the lowest average monthly flow rate, stream discharge has decreased to 0.058 m3/sec (2.0 ft3/sec). Mean stream flow rates do noth increase during the summer months, although nearly one-fourth of the annual precipitation falls during this period.


Fig. 6. Mean monthly discharge rates of Red Butte Creek just before it enters Red Butte Reservoir. Large and small tick marks indicate end-of-year and mid-year points, respectively. Data are from U.S. Geological Survey records.

Average monthly stream flow values, however, hide much of the stream dynamics and resultant impact on riparian vegetation. On a daily basis, stream flows can vary tremendously during snowmelt, depending on air temperature and snowpack depth (primarily that of upper Red Butte Canyon and Knowlton Fork). The 1982-83 winter was one of unusually high precipitation along the Wasatch Front. Heavy snows in mid-May 1983 were followed by equally unusual warm temperatures at teh end of the month. As a consequence, stream flow rates peaked at record values. On 28 May 1983, Red Butte Creek crested at a discharge rate exceeding 2.97 m3/sec (104.9 ft3/sec) (stream flow was above the maximum gage height), and overland flow was substantial. This was by far the greatest discharge rate in recent times, having eclipsed the previous maximum single day rate of 1.70 m3/sec (60.0 ft3/sec) measured on 18 May 1975 (U.S. Geological Survey Records).

More on Hydrology and Nutrient Flow

May 1983 (cont'd)
Stream Quality
Nutrient Concentrations