Arkansas River: September 2025 Archives

Tulsans were promised water in the river if we would only raise our taxes, but they neglected to tell us what would be in the water. Charles Pratt has been watching the City of Tulsa's water quality monitors and says that E. Coli levels at the end of August set a record. KTUL reported the story today.

When he crunched all the numbers from May to May, three out of four times, at least one gauge was in the red.

"During that time period, if you took all of the data, it was unsafe 72% of the time," he said.

At the time, the highest single test result was 6,100, but by the end of August, a new test result had taken the crown for the most E. coli.

"29,000," he said.

There are four gauges on the city's water quality dashboard: the I-244 bridge, the west bank boat ramp, the pedestrian bridge, and the kayak gate. The unit of measure is Most Probable Number (MPN) of organisms per 100 ml. The green, yellow, and red sections of the gauges appear to correspond to the levels described on this Wisconsin State Hygiene Laboratory webpage:

Various tests are used to investigate recreational water, stream or lake pollution, and wastewater treatment systems. The following are tests available for surface water testing:

E. coli: The only natural habitat of E. coli is the intestinal tract of warm-blooded animals.

• The recreational water guideline is less than 126 MPN/100 ml, averaged from 5 samples during a 30-day period.


• The single sample guideline is less than 235 MPN/100 mL.


• An advisory is recommended between and 235 MPN/100 mL and 1000 MPN/100 mL.


• A closure is recommended at greater than 1000 MPN/100 mL.

Enterococci: This refers to a subgroup of the fecal enterococci that includes Enterococcus faecalis, Enterococcus faecium, Enterococcus gallinarum and Enterococcus avium. The enterococci are used to indicate water quality.

• The recreational water guideline is 33 MPN/100 ml, averaged from 5 samples during a 30-day period.
• The single sample guideline is less than 61 MPN/100 mL.

Tulsa measures E. Coli but does not measure Enterococci. 100 mL is about 3 oz. That's the maximum size of a bottle of liquids you're allowed to carry on board an aircraft, so imagine 29,000 E. Coli bacteria floating around in a travel-sized bottle of shampoo.

Pratt says that a web search revealed that levels in raw sewage can range from 1,000 to 100,000 MPN/100 mL, so 29,000 would be 29 times the low end of that range, but I haven't been able to find the source that Pratt found. 29,000 would be 100 times the safe single sample level.

Page 20 of this EPA document has the Oklahoma water quality standards for Primary Body Contact Recreation, which correlate with the numbers shown above.

As I write this, the levels are 236 (red zone) at the boat ramp, 308 (red zone) at the I-244 bridge, but 30.5 at the kayak gate and 26.9 at the pedestrian bridge. All of the 30-day geometric mean values are in the green zone. 96.4 at I-244, 105.4 at boat ramp, 58.8 at kayak gate, 26.9 at pedestrian bridge.

E. Coli levels are measured twice a week, on Tuesdays and Thursdays. The city does not appear to provide historical data tables, but Mr. Pratt has been compiling the numbers. A KTUL story from May 3, 2025, has a year's worth of E. Coli data tabulated by Pratt. Here is the PDF of that year's worth of measurements. 92% of the time during the primary recreational months (May 1 through September 30), at least one of the monitors was in the red. Quality was better in the winter months when the river isn't used for recreation.

Interesting slide deck (PDF) on how E. Coli levels are measured and why E. Coli is used as an indicator species for the presence of fecal bacteria in water. Slide 8 states that it is "[i]mpossible to test for ALL pathogenic microorganisms, so test for easily detectable indicator organisms." Slide 10 states that "E. coli is the ideal indicator organism for testing water for fecal contamination" because of its "[a]bility to survive for extended period of time outside of the body ( especially in water: >120 days)," and it is a reliable indicator of fecal contamination, without other possible causes to rule out. E. Coli has both pathogenic and non-pathogenic strains, but "their presence indicates a pathway for human pathogens" such as giardia, cryptosporidium, hepatitis, and other waterborne viruses, bacteria, and protozoa.

MORE: Molly Bullock has been covering pollution in the Arkansas River in an ongoing series of articles starting in August 2023 at her Substack site Watershed. One of Bullock's focuses has been on industrial pollution, the legacy of over a century of oil exploration and refining and other industrial activity along the Arkansas River. Take a look at this article on plumes of apparent hydrocarbon pollution emerging near containment caps, and this follow-up on the hostile, passive-aggressive response from city officials to questions from citizens.

STILL MORE: Still bothered by statements made at the re-opening of Zink Lake last year that "Tulsans seeing water in Zink Lake for first time." Zink Lake was built in 1982, funded by Mayor Jim Inhofe's creative financing after voters rejected funding in the first attempt to pass a Third Penny sales tax for capital improvements in 1979. The dam was replaced, but the lake isn't new.