Research on a Mysterious Cave Helps Lend Insight on Improving Water Quality

Devil’s Icebox Cave in Rock Bridge, Missouri is a popular destination for tourists and locals alike. The cave, which is part of Rock Bridge Memorial State Park, is filled with myth and legend. Besides its ominous name, the cave features a long, steep wooden staircase leading to its frigid depths, and it is known for the variety of bat species that call it home, all adding to the cave’s allure.  To Robert Lerch, the cave houses other mysteries – such as how to improve water quality in a diverse watershed.

The entrance to Devil’s Icebox Cave.

Devil’s Icebox is located in the Bonne Femme watershed, a near 100 square mile area between Columbia and Ashland, Missouri. The watershed is home to pasture, forest, and crop lands, and is also rapidly urbanizing. Moreover, the watershed is a combination of glaciated areas in the upper reaches and karst topography and associated natural features in the lower reaches of the watershed.  This karst topography allows surface stream water, primarily originating from the glacial upland areas, to infiltrate directly into cave streams, as exemplified by the streams in Devil’s Icebox and nearby Hunter’s Caves.

Concerns about the water quality in the Devil’s Icebox Cave date back to the late 1960s, and several water quality studies have been conducted, and continue, in the cave. Intensive water quality monitoring in the Bonne Femme watershed was initiated at Hunter’s and Devil’s Icebox spring branches in 1999, and in 2003, the monitoring was expanded to include eight surface sub-watersheds, bringing the total number of monitoring sites to ten.

The monitoring project is led by Lerch, a soil scientist with the USDA-Agricultural Research Service, and supported by an interdisciplinary group of scientists and cave conservationists from Boone County, the University of Missouri, the Missouri Department of Conservation and others who are dedicated to studying the impacts of land-use on water quality and ecosystem function in caves and karst topography of the Ozark region.

These studies established that fecal bacteria was the major water quality problem, but sediment, nutrient, and herbicide contamination was chronic as well. Collectively, these studies led to broad awareness of the water quality problems in the watershed and better understanding of how surface land uses were impacting the cave streams.

From 2003-2007, a citizen-led stakeholder committee developed a watershed plan for Bonne Femme that focused on limiting development in flood plains, promoting conservation practices, and protecting sinkholes. This led to the development of a County Sinkhole Ordinance to manage land use activities within sinkhole drainage areas and contributed to the justification for hiring of an Urban Hydrologist by Boone County.

Currently, Boone County and its partners, including Lerch, have re-started water quality monitoring, established three sites for monitoring stream flow, and have collected samples to identify the potential sources of fecal bacteria in streams. The long-term goal is to work with land owners to promote conservation practices that will lead to improvements in water quality and help lend insight on how improve water quality in a unique landscape with diverse land uses. Lerch, an avid caver, hopes the research will also help preserve the lore of Devil’s Icebox, and caves like it, for generations to come.

Robert Lerch, USDA Agricultural Research Service

Dr. Lerch has been conducting research on the water quality of northern Missouri streams for over 25 years. His research encompasses the fate and transport of agricultural-derived contaminants, such as sediment, nutrients, and pesticides, and their impacts on water quality. His research focuses on understanding the factors controlling herbicide transport from fields to streams, including regional-scale assessments of watershed vulnerability to herbicide contamination, development and testing of best management practices (BMPs) to reduce contaminant transport, and long-term monitoring of stream water quality to assess trends. His new research includes studying the effect of cropping systems on greenhouse gas emissions and landscape position on denitrification.

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