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Identification and Analysis of Backwater Nursery Habitats in the Middle Green River, Utah, during 2014, 2017, and 2018 Using High-Resolution Optical Remotely Sensed Imagery

Technical Report ·
DOI:https://doi.org/10.2172/1922062· OSTI ID:1922062
Low-velocity channel-margin habitats, known as backwaters, serve as important nursery habitats for the endangered Colorado pikeminnow (Ptychocheilus lucius) in the middle Green River between Jensen and Ouray, Utah. The backwater synthesis report for the 1987–2013 period (Grippo et al. 2017) reported a decreased number of backwaters per river mile (RM) and an increased mean backwater size across the middle Green River. Information about backwaters is critical for understanding habitat characteristics that are important for Colorado pikeminnow recruitment. The goal of this study was to determine backwater number and size in the middle Green River using high-resolution imagery for 2018 to add to our understanding of long-term trends of backwater habitat availability across the reach. For comparative analysis of backwater habitats between 2004 and 2018, information for 2004, 2006, 2013, 2014 and 2017 from our previous studies was also utilized (Grippo et al. 2017; Hamada et al. 2017, 2021, and in review). Across the 2004, 2006, 2013, 2014, 2017, and 2018 study years, mean daily flow at the Jensen gage during image collection ranged from 1,220 cfs (2004) to 2,940 cfs (2014), which was approximately 140% greater in 2014 than in 2004. The number of delineated backwaters ranged from 88 (2013) to 245 (2017), and total backwater area ranged from 118,938 m2 (2006) to 209,611 m2 (2014). Mean backwater size ranged from 822 m2 (2017) to 1,508 m2 (2018), but there was considerable variability in backwater size for each of the study years. Backwater areas differed significantly among the study years based on a Kruskal-Wallis Rank Sum test (P < 0.001). Pairwise Wilcoxon tests indicated that the median backwater areas in 2017 and 2014 were significantly lower than in the other sample years (P ≤ 0.05), even though these years had the highest total backwater area. 2018 had the greatest median backwater area, although the distribution of backwater area values was not statistically different from backwater areas measured in 2013 (P > 0.05). These two years also had the lowest maximum backwater area values among all sample years. The distribution of backwater area values was not significantly different (P > 0.05) among the 2006, 2004, and 2013 sample years.
Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Organization:
USDOE Western Area Power Administration (WAPA)
DOE Contract Number:
AC02-06CH11357
OSTI ID:
1922062
Report Number(s):
ANL/EVS-20/5; 160628
Country of Publication:
United States
Language:
English