E coli Monitoring Program
Escherichia coli (E. coli), and fecal coliform are bacteria that inhabit the intestinal tracts of humans and other animals. Some strains of these bacteria are necessary for good health, but their presence in rivers indicates fecal contamination. While some amount of feces is expected from wildlife, high levels of E coli or fecal coliform highlight the potential for pathogens such as giardia and cryptosporidium. If you experience stomach cramps, diarrhea, or infections after water contact call your doctor. Risks can be minimized by keeping water away from open cuts, avoiding swallowing river water, and by avoiding swimming 2-3 days after a heavy rain event. Fecal contamination may occur from leaking septic systems, sewage spills, and stormwater runoff which may carry waste from pets, wildlife, and fertilizers into the river.
What levels of fecal bacteria are considered unsafe?
The Clean Water Act prohibits unsafe levels of fecal contamination in recreational waters. Oregon and Washington state environmental agencies use different fecal indicators to gauge safe levels of contamination and a different set of standards. The federal Environmental Protection Agency (EPA) oversees and approves state standards.
Columbia River Fecal Bacteria Standards
E coli (Oregon) No single, freshwater sample may exceed 406 per 100 ml, or the mean (geometric) of 5 samples taken within 30 days may not exceed 126 per 100ml
Fecal coliform (Washington) No more than 10% of samples may exceed 200 per 100 ml
*Oregon's Standard for a single E coli sample is one of the second highest in the country (406 per 100mL), while Vermont has the lowest state standard at 77 per 100 ml.
How can I help reduce fecal contamination?
- If you're on a septic system, contact your local county health department about tips for proper maintenance.
- Create a rain garden (bioswale) and disconnect your downspout to help filter stormwater run-off from populated areas. In many cities stormwater (from roofs and pavement) is piped directly to the river, or to waste water treatment plants that can be overwhelmed by floods and spill into the river.
- Plant a "riparian buffer zone", or a stretch of native vegetation along the shoreline to help absorb and filter water before it reaches a stream or river. 50 horizontal feet of shoreline vegetation helps with erosion control, 100 ft helps improve water quality, and 300 ft works as a wildlife corridor.
- Be a responsible river user. Use public restrooms, pack out your waste and your pets, and at the very least bury it at least 200 horizontal ft above the high water mark.
How do we monitor E coli?
Columbia Riverkeeper volunteers generally monitor E. Coli at recreational sites at least once a month, but if levels of E coli exceed standards monitoring is increased to evaulate the extent of the problem. Consistently high levels often indicate a failing sewage or septic pipe which can be sourced by monitoring upstream and downstream and comparing results.
We measure E coli with the IDEXX QuantiTray 2000 method, with equipment loaned to us from the Oregon Department of Environmental Quality (DEQ) . E. Coli is often measured in Most Probable Numbers (MPN), and involves a 24 hour incubation process where E. Coli cultures ingest a florescing agent which can be viewed and counted under a black light. Columbia Riverkeeper volunteers sample using DEQ methods and quality control procedures. All data is reviewed by DEQ and can be found on their online database http://deq12.deq.state.or.us/lasar2/.
Cooperating Groups:
Willlamette Riverkeeper, Addy Labs in Vancouver, Rosemere Neighborhood Association, Surfrider Foundation/Portland Chapter, and Oregon Dept. of Environmental Quality have all helped to make this program possible.
Questions?
Contact Lorri Eberle
Water Quality Volunteer Coordinator
541-399-0769 (office)
