HIGH-RESOLUTION SPATIAL AND TEMPORAL WATER QUALITY SAMPLING OF THE JORDAN RIVER, SALT LAKE CITY, UTAH

Per the Clean Water Act, the Jordan River in Salt Lake City, Utah is on the 305(b) and 303(d) list as impaired for dissolved oxygen (DO), total dissolved solids (TDS), and water temperature (Utah Division of Water Quality, 2016). The 8 segments of the river from Farmington Bay upstream to Utah Lake are impaired. Segments 1-3 are impaired for DO. Segments 1-2, 4-6 and 8 are impaired for TDS. Segments 5-7 are impaired for temperature. This study aims to better determine the sources of the impairments along the Jordan River by using high-resolution spatial and temporal sampling. 501 water samples, ranging from 2-8 samples per location at 84 locations, were taken in segments 2-6 from spring 2018 to winter 2020. Each sampling campaign lasted one week to provide a snapshot of each season. 147 out of 501 samples were above the 1200 ppm TDS standard set by UDWQ ranging from 1202-1679 ppm in segments 2-6 every season. Samples in segments 4-6 are most frequently seen above the TDS standard. The only summer sampling campaign was in 2018, and DO and temperature values that failed to meet UDWQ standards were found only in the summer. 3 of the 58 samples, all located in segment 3, were below the summer 2018 DO standard of 4.5 ppm ranging from 3.97-4.31 ppm. 48 of the 58 samples, located in segments 2-6, are above the 20°C standard set by the UDWQ ranging from 20.2°C-26.4°C. Five tributaries (3 rivers and 2 canals) flow into the Jordan River. Four did not exceed any of the UDWQ standards, but Little Cottonwood Creek, located in segment 3 exceeded the TDS standard by 38 ppm on average for the spring and fall of 2018 and winter of 2019. Per the data collected, the source of the impairment for the TDS appears to come from an upstream source as trends show a decrease in TDS downstream with no further impairments added into the river. It also appears that DO and temperature impairments occur only in the summer. This could be due to the limited riparian growth along the banks in addition to the confluence sources as all major confluences during the summer are above the temperature standard but not the DO standard. Further testing during the summer is needed to correlate the data. A continuation of this study is needed to get further data sets to allow a better understanding of the trends and possible sources of the impairments.