PFAS 'Forever Chemicals' Found Across Sedgwick County Surface Waters
Updated: 7 days ago
PFAS have become an increasing environmental concern across the country, but relatively little information has been available about what these chemicals look like in the waterways running through Sedgwick County. A recent community-led sampling project set out to change that.
PFAS, short for per- and polyfluoroalkyl substances, are a large family of man-made chemicals that have been used since the 1940s because they resist heat, water, oil and stains. They have been used in everything from industrial processes and consumer products to certain firefighting foams. The same qualities that make PFAS useful also make many of them extremely persistent in the environment, earning them the nickname “forever chemicals.”
The project, conducted as Elizabeth Toepfer’s Eagle Scout service project in partnership
with the Arkansas River Coalition, was designed to create a baseline picture of PFAS in surface waters across the Sedgwick County area. But the project was about more than simply collecting water. A final report has been published on our website.
Following the Water
Nineteen locations were selected across rivers, creeks, lakes, ponds and other waterways. A major part of the sampling strategy was intentionally designed from north to south.
Six locations followed the Big Arkansas River from north of Mount Hope, through Wichita, past Derby and ultimately toward Belle Plaine. Two additional locations provided a similar comparison along Cowskin Creek. Other samples included the Little Arkansas River, North and South Gypsum Creek, the Ninnescah River, several lakes and ponds, the Big Ditch floodway and treated wastewater entering the Big Arkansas River.
Why sample that way?
Because a single PFAS result tells you very little about where the chemical came from.
By starting upstream and repeatedly sampling the same river as it moved through rural areas, Wichita and communities farther south, researchers could look for changes in concentration along the way. Low upstream results followed by higher downstream results can identify sections of a waterway that deserve closer investigation.
The samples were collected using Cyclopure water test kits. Water passed through a DEXSORB extraction disc designed to capture PFAS compounds at the sampling location. The discs were then returned for laboratory analysis. The laboratory testing examined a broad panel of PFAS compounds using HPLC-MS/MS analysis with isotope dilution.
These were screening samples, not regulatory drinking-water tests. They provide clues about where PFAS is present and where additional investigation may be worthwhile, but they cannot by themselves determine a pollution source or whether a waterway is safe or unsafe.
*Important note #1: Drinking/tap water was not tested as part of this citizen-led surface water study.
For context, EPA’s PFAS benchmarks differ depending on what is being protected. The federal drinking-water limit for PFOA and PFOS is 4 parts per trillion, but EPA has also proposed much lower human-health criteria for surface water because people can be exposed not only through the water itself, but also by eating fish and shellfish that can accumulate PFAS over time. EPA’s draft criteria are approximately 0.0009 ppt for PFOA and 0.06 ppt for PFOS when considering both water consumption and fish/shellfish consumption. These are not enforceable federal limits, but they provide important context for understanding why even relatively low PFAS concentrations in rivers and streams may still warrant additional monitoring and investigation.
What We Found
PFAS was detected above laboratory reporting limits at 14 of the 19 sampling locations. Five locations had no targeted PFAS detected above their reporting limits.
More interesting than the overall detection rate was where the concentrations increased.
The Big Arkansas River showed one of the clearest patterns:
North of Mount Hope: No detection above the reporting limit
Ridge Road north of 53rd Street: 1.2 parts per trillion
North of Lincoln Street Dam: 2.3 ppt
Chapin Park/I-35: 10.2 ppt
Derby: 48.8 ppt
Belle Plaine: 35.3 ppt
The river therefore went from nondetectable or very low PFAS concentrations in the northern portion of the study area to substantially higher concentrations south of Wichita.
The treated effluent from the Wichita wastewater treatment plant was also sampled where it enters the Big Arkansas River south of Lincoln Street Dam and north of Derby. That sample measured 42.7 ppt and contained 10 detected PFAS compounds. The location and chemical similarities between that sample and the downstream Derby sample are consistent with the discharge contributing PFAS to the river, although the study cannot determine how much it contributes or whether other sources are also present.
Cowskin Creek produced the highest PFAS concentration in the entire project. The northern Cowskin Creek sample near Ridge Road and MacArthur measured 27.6 ppt, while the sample near Mulvane measured 62.4 ppt.
South Gypsum Creek was another area that stood out, measuring 34.3 ppt, compared with 5.4 ppt in North Gypsum Creek. Because these are separate drainage systems, that difference does not establish where the PFAS originated, but it identifies South Gypsum Creek as another logical target for future investigation.
Several locations also produced encouragingly low results. Afton Lake, Cheney Lake, the Ninnescah River and the northernmost Big Arkansas River location had no detections above their respective reporting limits.
What Comes Next
This study was never intended to provide the final answer about PFAS in Sedgwick County.
It was intended to figure out where we should look next.
And in that respect, the results accomplished exactly what the project was designed to do.
Rather than finding uniformly high PFAS concentrations everywhere, the testing revealed a geographic pattern. Several northern and standing-water locations were low or nondetectable, while higher concentrations clustered around Cowskin Creek, South Gypsum Creek and the Big Arkansas River south of central Wichita.
The next step should be more focused testing, especially along the Big Arkansas River between Wichita and Derby, around the wastewater discharge and mixing zone, along Cowskin Creek and within the South Gypsum Creek drainage. One round of samples cannot tell us everything. But it can tell us where to start asking better questions.
And now we know where to look.
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