Water residence time and water depth influence on nutrient conditions, eutrophication endpoints and habitat quality in backwater lakes of a large floodplain river

River Research and Applications
By: , and 

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Abstract

Many eutrophication studies focus on the external supply of critical nutrients like nitrogen and phosphorus, but hydrology and geomorphology can enhance or dampen the effects of excessive nutrient supply. We studied six backwater lakes in the Upper Mississippi River that varied in water residence time and water depth. Eutrophication in these systems is responsible for negative impacts such as cyanobacterial blooms and toxicity, and floating plant and algal mats that disrupt recreational water uses. Increasing backwater residence time was associated with more nitrate removal and a greater likelihood of nitrogen limitation, as well as greater accumulations of duckweed. Backwaters with greater depth and lower nitrogen concentration had less likelihood of filamentous algal accumulations. The median water residence time of backwaters with low duckweed (11.7 days) and no filamentous algae (16.9 days) approached the 12-day target to maintain overwintering conditions in backwaters for fisheries survival, supporting that water residence times in this range would likely improve both winter and summer water quality. Mean depth in backwaters with low duckweed and no filamentous algae was ~1.3 m, while shallower backwaters were more likely to produce duckweed and filamentous algae mats. This indicates that deeper backwaters might reduce the likelihood of eutrophication impacts. Natural resource management at the local level may not always be able to answer global and regional threats, but habitat restoration of hydrology and geomorphology can possibly alleviate or reduce large-scale threats at the local level.

Suggested Citation

Giblin, S.M., Larson, J.H., King, J.D., 2026, Water residence time and water depth influence on nutrient conditions, eutrophication endpoints and habitat quality in backwater lakes of a large floodplain river: River Research and Applications, https://doi.org/10.1002/rra.70083.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Water residence time and water depth influence on nutrient conditions, eutrophication endpoints and habitat quality in backwater lakes of a large floodplain river
Series title River Research and Applications
DOI 10.1002/rra.70083
Edition Online First
Publication Date November 21, 2025
Year Published 2026
Language English
Publisher Wiley
Contributing office(s) Upper Midwest Environmental Sciences Center
Country United States
State Minnesota, Wisconsin
Other Geospatial Upper Mississippi River
Additional publication details