Agricultural Issues Workgroup
Potomac River Basin Drinking Water Source Protection Partnership
As part of a multi-barrier approach to source water protection, the Partnership’s Agricultural Issues workgroup works to address the potential human health risks presented by agriculture in the Potomac River basin. With over 30 percent of the basin’s land in agricultural production, reducing runoff from farms into waterways is a Partnership priority.
Agricultural activities can affect water quality by contributing nutrients, sediments, pathogens, pesticides, and/or pharmaceuticals into the surrounding environment. Additionally, when water is treated at treatment facilities, natural organic matter (which maybe produced as a result of the runoff of nutrients from farms into receiving waters) in the water can react with disinfectants used in the treatment process that result in disinfection byproducts which are currently being researched for their human health effects.
Throughout the Potomac River basin a number of efforts are being undertaken to reduce runoff from farms. Many organizations provide technical and financial assistance to farmers in the region:
- Chesapeake Bay Program
- USDA’s Natural Resource Conservation Service – Maryland; Pennsylvania; Virginia; West Virginia
- Conservation Districts – Maryland; Pennsylvania; Virginia; West Virginia
Previous Partnership Activities
The Agricultural Issues workgroup focused on the risk to source water from Cryptosporidium (Crypto). While outbreaks of Crypto infection are rare, they can be severe. A severe outbreak of Crypto took place in 1993 in Milwaukee when the protozoa passed through the city’s filtration plant. The outbreak resulted in over 400,000 people suffering from severe diarrhea and over 100 deaths. Chlorination can work to remove Crypto from water, but it requires an extensive contact time (60 to 120 hours depending on concentration). Other disinfection processes may be more effective, such as ozone and UV. Therefore, source water protection is a key component for providing a robust, multi-barrier approach to minimizing the risk Crypto presents.
The EPA has developed the Long Term 2 Enhanced Surface Water Treatment Rule (LT2) to help public water utilities that rely on surface water to minimize the threat from Crypto. The rule requires a round of monitoring and increased treatment if the water supply is deemed to be at a high risk. Source water protection is included as one of the treatment options for source waters with higher levels of Crypto.
The Partnership organized a number of activities to educate members and the general public on the potential challenges posed by the presence of Crypto in the Potomac River basin:
- Webinar – Cryptosporidium, Cattle & Drinking Water – July 2010 and March 2011
- Ag 101 Workshop – August 2008
- Cryptosporidium Source Tracking Project – October 2006 through March 2008
- Pathogens Workshop – June 2005
The Partnership is hoping to build upon these efforts to work with the local agricultural community to promote best practices for controlling Crypto at its source. This may involve outreach and coordination with stakeholders in subwatersheds where there appears to be significant sources of Crypto.
- Canada Geese: Tranquil Symbol of the Wild or Pathogen Carrier? (Kristen L. Jellison, Opflow Online, August 2010) Note: subscription required.
Source water protection is critical to safeguarding public health from waterborne cryptosporidiosis. A better understanding of oocysts in watersheds, including their sources, transport dynamics, and potential to cause disease in humans, is necessary to decide if watershed control strategies are necessary. This study investigated the role of geese in disseminating human-pathogenic Cryptosporidium oocysts in the watershed for Philadelphia’s drinking water supply.