Water Quality Monitoring for Missouri National Recreational River (Bow Creek): 2021 Data Report

Rosse, Anine

The Northern Great Plains Inventory and Monitoring Network (NGPN) began monitoring water quality in Bow Creek at Missouri National Recreational River in 2015, with the assistance of the U.S. Geological Survey (USGS). This report summarizes the data collected during the 2021 ice-free season (March 24 through December 15) for water temperature, dissolved oxygen, specific conductance, and pH. Streamflow is measured year-round. This was the third season of continuous monitoring. 2021 ended up being a very dry year with less than 50% of the yearly average precipitation after an even drier year in 2020. Daily mean discharge peaked at 425 cubic feet per second (and maximum instantaneous discharge of 556 cfs) on February 24, 2021, considerably lower than the record peak in 2019 of 12,500 cfs, which translated to below average streamflow. Water quality also was measured including in 2015 which had a peak of 2,220 cfs, and 2018 which had a peak of 7,440 cfs. There was considerable seasonal variation in all water quality measures. A summary of our results can be found in the Descriptive Statistics Summary tables for the ice-free season (Table 2) and for each month (Table 3). Water temperature exceeded state standards 3.82% of the time. Nebraska Department of Environment and Energy monitors Escherichia coli (E. coli) bacteria in Bow Creek. E. coli can be a human health concern. Between 2016 and 2021, bacteria levels exceeded standards for moderately used recreational waters (298 cfu/100 mL) 83 % of the time in reach (MT2-11300) and the geomean standard (126 cfu/100 mL) exceeded standards in 2016 and 2020. Bow Creek remains nonsupporting of its recreation use due to E. coli. There is no approved TMDL for E. coli, placing it in category 5, but Lewis and Clark NRD does have a watershed plan to improve the water quality in Bow Creek. NGPN’s collaboration with USGS supported real-time and archived access to this data through the USGS National Water Information System Website Bow Creek near Wynot, Nebr. - USGS Water Data for the Nation where it remains available to the public.