Water quality, sediment, and soil characteristics near Fargo-Moorhead urban areas as affected by major flooding of the Red River of the North

Authors: GUY, ADAM - Fort Berthold Community College; DESUTTER, TOM - North Dakota State University; CASEY, FRANCIS - North Dakota State University; KOLKA, RANDY - Forest Service (FS); Hakk, Heldur

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2011
Publication Date: 1/26/2012
Citation: Guy, A.C., DeSutter, T.M., Casey, F.X.M., Kolka, R., Hakk, H. 2012. Water quality, sediment, and soil characteristics near Fargo-Moorhead urban areas as affected by major flooding of the Red River of the North. Journal of Environmental Quality. 41:554-563.

Interpretive Summary: Spring flooding of the Red River of the North (RR) is common, but no information exits on how these flooding events impact water and sediment quality within an urban area. The objectives of this study were to assess if urban environments affect floodwater quality, and to determine the quality of sediment deposited in an urban environment after floodwaters recede. Water samples were taken repeatedly from an upstream and downstream location from Fargo, North Dakota and Moorhead, Minnesota (F-M) during major RR flooding, while flood-deposited sediment and the underlying soil were collected from three locations within F-M after flooding. Water and sediment/soil samples were measured for multiple environmentally relevant endpoints. Physical and chemical concentrations were similar at both water sampling sites. 17B-estradiol and petroleum-derived organics were detected in about one third of the water samples, but at concentrations below the level of concern. Sediment samples closest to the river channel had higher deposits of sediment and, consequently, the greatest concentration of multiple chemicals. Petroleum-derived organics were detected in nearly all sediment samples. The average total mercury concentrations in the flooded sediment and underlying soil samples were the same, and all trace elements detected in flooded sediments were within ranges for observed for non-contaminated soils. Although flooding has economic, social, environmental impacts, this study does not indicate that flooding in the RR in F-M led to decreased quality of water or sediment.

Technical Abstract: The objectives of this study were to assess if urban environments affect floodwater quality, and to determine the quantity and quality of overbank sediment deposited in an urban environment after floodwaters recede. Water samples during major flooding of the Red River of the North (RR) were taken on 12 dates from two locations upstream and downstream of Fargo, North Dakota and Moorhead, Minnesota (F-M), and were measured for 12 variables. Overbank sediment and underlying soil samples were collected from three locations within F-M in three equidistant transects parallel to the river channel. Sediment and soil samples were analyzed for 37 variables including carbon, nitrogen, diesel-range organics, and trace elements. Physical and chemical concentrations were similar at both water sampling sites. 17B-estradiol was detected in 9 of 24 water samples with an average concentration of 0.61 ng L-1 and diesel-range organics were detected in 8 of 24 samples with an average concentration of 80.0 ug L 1. The deposition of sediment ranged from 2 to 10 kg m 2. Samples closest to the river channel had higher deposits of overbank sediment and the greatest level of chemicals. Diesel-range organics were detected in 26 of the 27 overbank sediment samples (maximum concentration = 49.2 mg kg 1). The average total Hg concentrations in the overbank sediment and soil samples were 55 and 61 µg kg 1, respectively, and all trace elements detected in the overbank sediments were within ranges for non-contaminated soils. Although flooding has multiple impacts within a community, this study does not indicate that flooding of the RR in F-M led to decreased quality of water or sediment.