Water Quality Measurement | Biological Parameter
Lake Pend Oreille | Pend Oreille River
Total Coliform Bacteria and E. coli are important because they serve as indicators for other, more pathogenic bacteria and viruses, especially those shed with human feces. Fecal contamination can include viruses like Hepatitis A, and bacteria like Shigella spp. or Vibrio cholera from humans, while wild or domestic animal feces may contain parasites such as Giardia spp., Cryptosporidium spp., or Salmonella. High levels of indicator bacteria may indicate high levels of these other pathogens as well.
Total coliform bacteria and E. coli measurements are very important to our high-use public access areas, like Sandpoint’s City Beach. Our measurements are recorded in MPN/100mL or “Most Probable Number” per 100 mL of water, which is a statistical probability of the number of organisms present in the water. The U.S. Environmental Protection Agency recommended level of E. Coli is 126 CFU/100 mL for fresh water, as designated in their 2012 Recreational Water Quality Criteria. CFU stands for “Colony Forming Units” and represents an actual measurement in comparison to the statistical estimate of MPN.
LPOW generally finds very low concentrations of these indicator bacteria in our lake and river, which is great news for everyone who enjoys our swimming and recreation areas!
We measure the amount of E. Coli in the water each time we collect data – once a month for five months out of the year (June – October). The bars represent the upper quartile (75% of the data taken at this site falls below this line), the median (or mid-point of the data) for each site, first quartile (25% of the data taken at this site falls below this line), and the box represents the middle 50% of the data.
Use our interactive graph to check out all the data we have collected since 2012. Hover over a data point to see more information or try clicking on the name of a month to see all the data for just one month!
Support this Program!
Laboratory analysis of water samples are very expensive totalling about $1,000 per station per field season. Your donation helps cover the costs of collecting & analyzing water samples.
Become a Citizen Scientist!
Become a trained citizen scientist. Collecting water samples is a great way to enjoy time on the water & get involved in active stewardship of our local waterways!