This post is part of a series for 2019 Watershed Awareness Month, comparing water quality in a pair of local creeks to learn how land and people influence water.
On May 20, the Skunk River Paddlers launched their canoes and kayaks on Squaw Creek at 100th Street in Hamilton County and paddled down to 140th St in Boone County. The recent rains made it a fast ride!
However, the rain also washed a lot of sediment and quite likely some land-applied manure into the stream. I collected a water sample just before I took this photo and had a lab test it for E. coli bacteria, an indicator of fecal contamination: 2,390 CFU (Colony Forming Units)/100mL. That’s 10 times the primary contact standard for a single sample (235 CFU/100mL) and just shy of the secondary contact standard (2880 CFU/100mL).
Later that day, I collected a sample from Brookside Park in Ames with the help of my son. The lab results came back at 12,800 CFU/100mL, well above the secondary contact standard!
I don’t want to discourage people from recreating in Squaw Creek but I think a safety reminder is necessary:
Squaw Creek has consistent fecal contamination that could pose a risk of acquiring a waterborne illness. The risk is higher after heavy rains when the water is muddy—consider wearing waterproof boots when wading under these conditions. If you come into contact with the water, wash your hands or apply hand sanitizer before eating and take precautions to avoid getting river water in your mouth or on an open cut.
The numbers above are high, but not unprecedented. Over the past three years, City of Ames staff have been tracking E. coli, nitrogen, and phosphorus in Squaw Creek at Lincoln Way and we’ve been sharing the data on our website. 46 out of 48 samples exceeded the primary contact standard for E. coli!
The pattern is also not unusual. In our Snapshots, we see that Squaw Creek usually exceeds the standard by the time it reaches Ames and picks up additional fecal contamination by the time it reaches Duff Ave.
The Ames City Council, Public Works Department, and Water & Pollution Control Department are concerned by the data and committed to helping find and address sources of contamination within city limits. The City of Ames spends $3.5 million a year repairing and upgrading its sanitary sewers. However, the data point to multiple sources of E. coli that will make this a difficult problem to solve. In addition to sewer leaks, we probably have some failing septic systems in the upper watershed, cattle in the stream, land-applied manure carried by runoff, pet waste, and wildlife. E. coli can also persist for a while in the sediment, and gets stirred up again after a rain.
In June, I went back to Brookside Park to demonstrate some water quality testing for kids enrolled in the Community Academy summer program. In addition to exploring nature and food systems, the kids have been hard at work improving removing invasive species, planting pollinator gardens, improving trails, and coming up with interpretive signs for Brookside Park. I’m pleased to see that one of the signs is about water quality, including a reminder to wash your hands after entering the creek, and tips on how to reduce pollution. Look for the signs to go up later this summer.