181-5 Combined Impacts of Land Use and Climate Change on Manoomin in the Otter Tail River Watershed, Minnesota

Session: Community Engaged Research for Environmental Sustainability and Community Resilience (Posters)

Poster Booth No.: 24

Presenting Author:

Amelia Olsen

Authors:

Olsen, Amelia E.¹, Dickenscheidt, Madeline G. ², McClure, Gracelyn³, Capron, Shauna⁴, Nooding, Zhaashiigid⁵, Keezer, Renee⁶, Ng, G.-H. Crystal⁷, Santelli, Cara M.⁸

(1) University of Minnesota - Twin Cities, Minneapolis, MN, USA, (2) University of Minnesota - Twin Cities, Minneapolis, MN, USA, (3) University of Minnesota - Twin Cities, Minneapolis, MN, USA, (4) University of Minnesota - Twin Cities, Minneapolis, MN, USA, (5) White Earth Tribal and Community College, Mahnomen, MN, USA, (6) White Earth Department of Natural Resources, Mahnomen, MN, USA, (7) University of Minnesota - Twin Cities, Minneapolis, MN, USA, (8) University of Minnesota - Twin Cities, Minneapolis, MN, USA,

Abstract:

Wild Rice (Zizania palustris), known to the Ojibwe as Manoomin and to the Dakota as Psiη, is a species of economic and cultural importance to the tribal nations of the Great Lakes Region. Wild Rice has all but disappeared from Michigan and is in decline throughout Minnesota and Wisconsin. As a sensitive annual grass, Manoomin is at risk from effects of climate change and land use change as well as competition from other aquatic plant species. The access and harvest rights to Manoomin in ceded territories are protected by treaty rights for all enrolled tribal citizens. The Otter Tail River Watershed (OTRW) covers 1,249,541 acres of predominantly agricultural land, located in west-central Minnesota. The OTRW contains over 2,800 miles of streams and 1,300 lakes, with headwaters on the White Earth Band of Ojibwe Reservation. The application of agricultural chemicals including fertilizer and pesticides can lead to runoff and infiltration into surface and ground waters. The impact of agricultural pollution on natural water bodies has been recorded through decades of water sampling data from the Minnesota Departments of Agriculture, Health, Natural Resources, and the Minnesota Pollution Control Agency. However, the direct impact of agricultural pollution on Manoomin is understudied. In collaboration with the White Earth DNR and Tribal Research Review Board, sampling of surface waters (rivers and lakes) and groundwaters (domestic wells) was performed at ten locations throughout the OTRW. Analysis of nutrient anions, metals, and pesticide concentrations was conducted to determine the transient and lasting presence of agricultural chemicals in the watershed. Preliminary results from the past three years of OTRW sampling have shown widespread Atrazine and 2,4-Dichlorophenoxyacetic acid contamination in surface waters. This contamination has been seen at our “control sites” upstream of the majority of agriculture. Historical data from the watershed has also shown accumulation of both pesticides and nutrients in groundwater. Nutrient data has highlighted both temporal and spatial patterns of elevated nutrient levels in the watershed. Results from this work will allow a better understanding of how agricultural land use impacts water chemistry and Manoomin health, both in the OTRW and beyond. This knowledge will be used to project forward, assessing climate change impacts, particularly the effects of shifting precipitation patterns on surface runoff and groundwater fluxes.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9440

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