Stream corridor sources of suspended sediment and phosphorus from an agricultural tributary to the Great Lakes

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Abstract

Fine-grained sediment and phosphorous are major contaminants in the Great Lakes and their tributaries. Plum Creek, Wisconsin (92 km2), a tributary to the Lower Fox River, has a Total Maximum Daily Load (TMDL) requiring reductions of suspended sediment and phosphorus loading by 70% and 77%, respectively. In 2016-18, an integrated sediment fingerprinting and stream corridor-based sediment budget study was conducted to help quantify upland and stream corridor sources of suspended sediment and phosphorus at a loads monitoring station on Plum Creek. Sediment fingerprinting results indicated that the proportion of upland and stream corridor sources of suspended sediment in Plum Creek varied by season and the amount of runoff; however, bank and gully erosion accounted for 51% and 24% of the suspended sediment annual load, with one or both sources present in all seasons. The next most common source was roadside ditches (11%), which was also present in all seasons. Cropland and woodland sources accounted for small proportions of the suspended sediment, with cropland mainly in summer and woodland in winter, spring, and summer. Relative source proportions for sediment-bound phosphorus were similar to suspended sediment but made up less of the overall loading because on average 27% of the phosphorus load resides in the dissolved phase. Soft fine-grained streambed sediment had source signatures of mainly bank, gully, and ditches (ordered by decreasing proportion). Results from the field-based rapid geomorphic assessment supported the sediment fingerprinting results and in general showed that the amount of bank erosion increases in a downstream direction. The high proportion of sources from banks and gullies is due, in part, to a 20-km long, deeply entrenched valley and steep eroding bluffs between the majority of cropland and the Plum Creek water monitoring station.

Study Area

Publication type Conference Paper
Publication Subtype Conference Paper
Title Stream corridor sources of suspended sediment and phosphorus from an agricultural tributary to the Great Lakes
Year Published 2019
Language English
Publisher Federal Interagency Sedimentation and Hydrologic Modeling Conference
Contributing office(s) California Water Science Center, Maryland Water Science Center, Wisconsin Water Science Center, Upper Midwest Water Science Center
Description 305, 15 p.
Larger Work Title SEDHYD 2019 Proceedings
Conference Title SEDHYD 2019
Conference Location Reno, NV
Conference Date June 24-28, 2019
Country United States
State Wisconsin
Other Geospatial Plum Creek
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