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Reconnaissance study of watershed and cave sediment sources discharging from a karst spring, Iowa
Journal article   Open access   Peer reviewed

Reconnaissance study of watershed and cave sediment sources discharging from a karst spring, Iowa

Keith E. Schilling, Joseph Honings, Thomas Doyle, Calvin Wolter and David Peate
Agrosystems, geosciences & environment, Vol.9(3), e70401
07/19/2026
DOI: 10.1002/agg2.70401
Appears in  UI Libraries Support Open Access
url
https://doi.org/10.1002/agg2.70401View
Published (Version of record) Open Access

Abstract

Springs discharging from karst landscapes provide sustainable flows to natural ecosystems and support productive fish hatcheries but sediment discharging from springs threatens the long‐term sustainability of hatcheries. In this study, we conducted a reconnaissance study to evaluate watershed and cave sediment sources discharging to Siewers Spring fish hatchery in northeast Iowa. Representative sediments were collected from streambank, streambed, and upland locations from watersheds draining to Siewers Spring and additional bed and bank sampling was collected inside nearby Coldwater Cave to assess sediment sources. Sampling of spring export at two locations characterized sediment discharge. Sediment characterization, including particle size, nutrients, and minor and trace elements, was used in an unmixing model to estimate sediment source contributions. Streambank erosion sources and cave bed and bank sources were the dominant sediments discharging from the cave, although variations in relative proportions were associated with differences in sediment source target values. Upland sources were relatively minor compared to other sources. Although more work is needed to better characterize sediment discharge and source populations, study results can be used as a preliminary guide for watershed managers to direct conservation efforts and to manage expectations. Sediment source apportionment is an appropriate methodology to identify sediment sources to karst springs if access to cave sediments is available. Sediment discharged from springs can impact local ecosystems including fish hatcheries that use spring water as a water supply. Reducing sediment impacts requires knowing the source of the sediment so corrective actions can be taken. In this study, we conducted a reconnaissance study to evaluate sediment sources discharging to a karst spring in northeast Iowa. Representative sediments were collected from streambank, streambed, and upland locations from watersheds draining to Siewers Spring and additional sampling inside nearby Coldwater Cave was used to assess cave bed and bank sediment sources. Particle size, nutrients, and minor and trace elements were used in an unmixing model to estimate sediment source contributions. Streambank erosion sources and cave bed and bank sources were the dominant sources and upland cropped fields were relatively minor. Study results can be used to direct conservation efforts and manage expectations.
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