Streamflow investigations on a reach of Hobble Creek near Springville, Utah

The Central Utah Water Conservancy District (CUWCD) is proposing to deliver supplemental flow to Hobble Creek from Strawberry Reservoir through the Mapleton-Springville Lateral pipeline. A substantial portion of the supplemental water is intended to benefit June Sucker recovery and other fish and wildlife along Hobble Creek. The objective of this study was to determine gains or losses of water in a section of Hobble Creek between the Island Dam and the Swenson Dam (the primary study reach) during different seasons and flow conditions.

Paired measurements of flow in Hobble Creek were made during June to November 2016, at sites bracketing the primary study reach from site HC3 to HC6. These measurements showed increased streamflow in this reach that ranged from 6.1 cubic feet per second (ft³/s) to 9.3 ft³/s. During August and November, two sets of measurements were made at several locations along the study reach to document baseline conditions, and then an additional amount of water (a pulse of about 9–10 ft³/s) from Strawberry Reservoir through the Mapleton-Springville Lateral pipeline, was added to the reach. During the August 23 measurements, the average change at the upstream site (HC3) relative to the pulse was 9.3 ft³/s, and the average change at the downstream site (HC6) was about 8.4 ft³/s, leaving about 0.9 ft³/s of the additional water unaccounted for at site HC6. However, there was no significant difference between the net streamflow volume at sites HC3 and HC6 associated with the pulse that would indicate water was being lost. During the November 7–9 streamflow measurements, the average change in discharge at site HC3 relative to an increase in flow from the Mapleton-Springville Lateral pipeline (the pulse) was 9.6 ft³/s, and the average change at site HC6 was about 9.8 ft³/s. On the basis of these measurements it appears that the entire amount of the pulse added to the stream at site HC3 was accounted for at site HC6. Additionally, there was no significant difference between the net streamflow volume at sites HC3 and HC8 associated with the pulse that would indicate water was being lost.