Beach Bacteria Blues: Can We Fix Our Favorite Swimming Spots?
"Uncover the hidden sources of bacteria at your local swimming hole and learn about new modeling approaches that could help clean up our beaches."
Imagine a hot summer day, the sun is blazing, and all you want to do is take a dip in the cool, refreshing waters of your local lake or beach. But what if that water isn't as clean as it looks? Inland lake beaches are a major source of recreation, and when these areas are impaired due to poor water quality major economic losses can occur in local communities. Pathogens are the primary cause of surface water impairments in the United States.
Every year, countless beaches are closed or face warnings due to high levels of bacteria, making what should be a fun outing a potential health hazard. The U.S. Environmental Protection Agency (USEPA) has developed stringent water quality standards to protect humans from exposure to pathogen contaminated waters. Fecal indicator bacteria (FIB) such as the fecal coliforms, enterococci, and Escherichia coli are primarily used to detect fecal contamination as they are the preferred indicators of pathogens in waters. But where does all this bacteria come from, and what can be done to fix the problem?
A recent study focused on Hickory Grove Lake in Iowa offers some insight, exploring a novel approach to pinpoint bacteria sources and set Total Maximum Daily Loads (TMDLs) – essentially, pollution cleanup targets – for beaches. The goal is to determine all the factors affecting the bacteria movement, decay, and growth in lake waters needed to develop reliable bacteria TMDLs for inland lake beaches.
Decoding the Bacteria Mystery: Where Does It Come From?
Traditionally, identifying the sources of bacteria in a lake or beach is a complex task. It involves considering everything from agricultural runoff to failing septic systems. In the case of Hickory Grove Lake, researchers identified a few key culprits:
- Unpermitted septic systems leaching into the water
- Manure applications in the surrounding watershed
- Livestock with direct access to streams
- A surprising amount from waterfowl and wildlife
Cleaning Up Our Act: Future Steps for Healthy Beaches
The approach used at Hickory Grove Lake offers a promising alternative for setting beach bacteria TMDLs, particularly when the primary source is localized. Identifying the sources of contamination and the degree of contaminant loads received by the waterbody are the first steps in the TMDL development process. The near shore beach volume model approach proposed here is a viable alternative for setting load reductions at bacteria impaired beaches, where the predominant source of E. coli is waterfowl. Future research should focus on improving our understanding of how bacteria interact with beach sediments and refining models to better predict bacteria levels in complex environments. The NBSV approach would allow Clean Water Act Section 319 implementation funds to target the localized contributions from geese and increase the likelihood of achieving water quality improvements.