Update 2020-01-30: Florida Counties Task Force in Valdosta about sewage 2020-01-08.
We do already have Lowndes County’s results, and they show somewhat elevated E. coli counts at both Okapilco Creek south of US 84 and the Withlacoochee River at US 84, for Wednesday of last week, January 22, 2020. Both those sites are upstream of Knights Ferry and State Line (GA 31), where WWALS found too-high counts on Sunday, January 26. Below: what these numbers mean, and how you can help.
Elevated at both Okapilco Creek and US 84 Withlacoochee 2020-01-22
The entire WWALS composite spreadsheet is on the WWALS website.
Sara Jay pulled some upstream river samples yesterday, so her results should be ready later today or early tomorrow. I’m going to get some downstream ones and at Okapilco Creek at US 84 today. Lowndes County is also pulling samples today, so my results should be ready tomorrow or very early Friday. Lowndes County is pulling samples today, so their results should be available tomorrow or Friday. We also hope to get updates from Florida.
People want to know what do these numbers mean?
TNTC means Too Numerous to Count, which means many thousands of cfu/100 mL.
Above 1,000 is cause for high alert, and I’d not want to get close to that water without gloves and I wash my clothes afterward.
Above 410 is likely to make some people sick, and I would not want to get that water on me.
Above 126 long-term is not good, and is likely to make some people sick.
Cautions derived from any of these numbers have to be advisory, because nobody can predict exactly who or how many will get sick from any level of E. coli. However, it seems obvious that the higher the level the more public health danger.
One person asked, what level of E. coli would close a public swimming pool? Theoretically, very low levels, but exactly what level depends on local authorities.
Many of these questions seem like they would have simple answers. but it’s complicated. That’s partly because it’s very hard to predict what actual health complications will occur from any given level of E. coli. Different people react differently; very young and very old people may be more susceptible. People get different levels of exposure: drinking the water is obviously likely to make you sick, but even getting it on your skin can be bad, especially if you have scratches or sores. Some people may fall ill and others may not, at any level of E. coli. But it’s pretty clear that the more E. coli the more likely more people will become ill.
OK, what does EPA recommend for recreational waters? In 2012, EPA updated its Recreational Water Quality Criteria, the short version of which for E. coli is:
Estimated Illness Rate 36/1,000
Estimated Illness Rate 32/1,000
|E. coli (fresh)||126||410||100||320|
OK, what does that mean?
GM is geometric mean, for longterm levels.
STV is statistical threshold value, and “is intended to be a value that should not be exceeded by more than 10 percent of the samples taken.”
So long-term we want E. coli below 126, by Recommendation 1 (or below 100 by Recommendation 2). Which is what we’ve been seeing lately in most of the WWALS, Lowndes County, and Florida samples.
Except the Lowndes County last Wednesday levels of 397 at US 84 on the Withlacoochee River and 365 below US 84 on Okapilco Creek were above 126. They were also above the Recommendation 2 STV level of 320 (although not above the Recommendation 1 level of 410).
Which Recommendation should we use? EPA provided no guidance on that. In these tables, WWALS has generally been using the Recommendation 1 STV levels of 410 to mark samples red, 126 to mark samples orange.
This is mostly because Recommendation 1’s “Estimated Illness Rate of 36/1,000” seems to be more traditional. Personally, I prefer Recommendation 2’s “Estimated Illness Rate of 32/1,000” because I don’t want anybody to get sick.
In the spreadsheets received from the Florida agencies, apparently they are also using Recommendation 1:
Red text indicates that: Fecal Coliform levels exceeded 800 CFU/100mL on any one day, or that Escherichia coli levels exceeded the surface water quality standard of 410 MPN/100mL
In case you’re wondering, MPN is Most Probable Number and is practically equal to the CFU for Colony Forming Units that WWALS and Georgia Adopt-A-Stream use. So MPN/100 mL == cfu/100 mL. They are both estimates of how many bacteria are found in a mililiter of water, after incubation over 24 hours +/1 an hour.
Georgia Adopt-A-Stream’s Bacterial Monitoring Manual goes by EPA’s previous, 1986, recommendations. GA AAS says:
Recommended E. coli Standards for Recreational Waters
The US EPA recommended E. coli as the freshwater quality criterion for bacteria in the Ambient Water Quality Criteria for Bacteria document published in 1986 — a departure from earlier recommendations of total coliform and fecal coliform. The E. coli recommendation resulted from epidemiological studies that found that E. coli was statistically correlated with swimming-related gastrointestinal illnesses.
EPA’s recommended limit of E. coli within recreational waters such as swimming and water skiing (full body contact) within recreational waters is equal to or less than 126 cfu/100 ml (colony forming units per 100 milliliters of water) based on a geometric mean or a one-time measurement equal to or less than 235 cfu/100 ml. EPA recommends a set of standards for E. coli in fresh water bodies as a single maximum allowable count. These rates correspond to an acceptable risk level of 8 people out of 1000 getting sick.
Designated Swimming Moderate Swimming Area Light Swimming Area Infrequent Swimming Area E. coli
What’s a designated swimming area? I’d say any boat ramp or other public river boating access area.
What’s “contact”? Children playing in the water are contacting the water. People getting into or out of kayaks or canoes are likely to contact the water, which is also likely to drop onto them off their paddles.
GA AAS further remarks:
It is common to find high bacteria counts in urban areas. E. coli counts (cfu/100ml) that exceed 235 cfu/100 ml are considered “high” and should be closely monitored, but when counts exceed the 1000 cfu/100 ml threshold, they warrant special action. A count of 235 cfu/100 ml correlates to 8 incidents of 1000 people getting sick, but a count of 1000 cfu/100 ml correlates to about 14 incidents of 1000 people getting sick.
The Withlacoochee River below Sugar Creek (and Okapilco Creek most anywhere) are not in urban areas, so they should always be below 235 one-time or 126 long-term. Before the December 2019 Valdosta record-largest raw sewage spill, WWALS was usually getting counts of zero (0) at Knights Ferry, Nankin, and State Line.
For Fecal coliform, GA AAS goes by Georgia standards that vary wildly from 200 cfu/100 mL for a 30-day geometric mean for Recreational waters. Or 200 only for May through October for Fishing waters, with 1,000 for November through April, with a maximum of 4,000 Nov-Apr.
A catch is that Georgia by default classifies all rivers as Fishing, the lowest level, with the most lax restrictions on E. coli. That’s why Suwannee Riverkeeper and the other eight Riverkeepers of Georgia asked in the Georgia Triennial Review of Water Quality Standards for Georgia to reclassify all our rivers as Recreational. (Florida already classifies all rivers as Recreational by Default). Whatever Georgia does in that Review, Suwannee Riverkeeper goes by Recreational standards for all our rivers.
Remember, cautions derived from any of these numbers have to be advisory, because nobody can predict who or how many will get sick.
Suzy Hall with a Petrifilm.
Each bacterial test costs $6 for Petrifilms alone.
WWALS is spending about $40 a day on Petrifilms and other materials after this Valdosta spill.
Maybe you want to get trained and help test; if so, follow this link.
-jsq, John S. Quarterman, Suwannee RIVERKEEPER®
You can join this fun and work by becoming a WWALS member today!