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.
|Clear Creek @Hyland on May 18
|Clear Creek@ Hyland on May 24
|Transparency > 60 cm
|Transparency of 1 cm
|Orthophosphate 0.1 mg/L
|Orthophosphate 5 mg/L
Clear Creek was true to its name on May 18 when the Squaw Creek Watershed Coalition did its spring water quality snapshot. Long-time member Ed Engle and three Ames High School students (Wil, Becca, and Nate) filled a transparency tube to the top (60 cm) and the secchi disk at the bottom was clearly visible. A week later, Rick Dietz tested the same location after a 1.7 inch rainstorm and couldn’t see the disk until he’d poured out all but 1 cm of the water!
Water quality can change rapidly. Sediment* in the water spikes during and after a big rain storm. So does phosphorus and E. coli. Nitrate and chloride show strong seasonal patterns. While some of that variation may average out in a big dataset, when streams are sampled less often, it can be tricky to make an apples-to-apples comparison. That’s why water quality snapshots—multiple streams sampled on the same day—are so valuable.
*measured as clarity, turbidity, or total suspended solids
The Coalition has been monitoring Clear Creek since 2007. It normally has pretty good water quality, with orthophosphate near the outlet averaging 0.2 mg/L and transparency averaging 43 cm. 23% of the riparian area is forested (Pammel Woods, Munn Woods, and Emma McCarthy Lee Park) so that’s part of the reason. Another reason is the efforts of some farmers in the watershed. Jeremy Gustafson has been improving his soil and protecting water through his innovative use of cover crops–planting soybeans into living rye and using diverse mixes after oats.
Still, there’s room for improvement. Nitrate levels average 5.7 mg/L in Pammel Woods, and 7.5 mg/L at the Boone-Story county line. (For reference, nitrate was historically less than 2 mg/L). And as the “gully washer” of May 24 shows, the relatively flat “Des Moines Lobe” region of Iowa is not immune to soil erosion! More no-till, cover crops, and prairie strips could further reduce erosion. More sediment ponds, wetlands, and buffers could prevent sediment from reaching the creek.
Clear Creek, College Creek, and Worrell Creek all start in Boone County and join Squaw Creek in Ames. We’ll continue to support conservation practices in these watersheds through our Small Landowner Assistance project (wrapping up this year) and our National Fish and Wildlife Foundation grant (just getting going). If you live or farm west of Ames and are thinking about conservation, or know someone who does, give us a call!