Current Water Quality in Story County

Water levels in rivers

To avoid dragging your canoe when paddling the South Skunk River, you’ll need at least 90-110 cfs at the USGS gage north of Ames.

As of Sept 10, the drought conditions range from severe in northern Story County to moderate in the southern part of the county.  In between infrequent rains, many streams have been drying up, except for deeper pools.  Ioway Creek reached 200 cfs after rains on Aug 31, but it was short lived, dropping to 5 cfs in 24 hours.

The Skunk River Paddlers also have information about the South Skunk River water trail and links to current water conditions.

South Skunk at W Riverside Road / near Ames USGS Water-data graph for site 05470000, South Skunk near Ames, IA

Fecal bacteria

E. coli bacteria is an indicator of fecal contamination. Not everyone who goes swimming or boating will swallow water, and not everyone who swallows water will get sick if there is human or animal waste in the water, but when E. coli is high, there is a greater risk.  Water quality may have changed since the last sample, so take greater precautions if it has rained recently and the water is murky.

 … in Lakes

Iowa DNR and local partners monitor public swimming beaches on weekly basis from Memorial Day to Labor Day, with results posted here.   The 2021 monitoring season is now closed.

The primary contact recreation standard is 235 colonies per 100mL for a single sample.  During the 2021 season, 2/15 samples at Peterson Park beach and 3/15 samples at Hickory Grove Lake beach exceeded this threshold.  For evaluating the entire season, the standard is a geometric mean of less than 126 colonies/100mL.  Both beaches were within the standard, with geometric mean of 58 colonies/100mL at Hickory Grove Lake and 17 colonies/100mL at Peterson Park. 

Hickory Grove Lake is on the Impaired Waters List due to high E. coli levels and excessive algae growth in previous years but there has been extensive work to improve water quality.

kids at beach

 … in Rivers

Rivers and streams in central Iowa frequently have E. coli levels above the state standard.  When enjoying paddling or fishing take some extra precautions to avoid accidentally getting river water in your mouth or on food.  We monitor 15 streams in Story County for nutrients and fecal bacteria, but keep in mind conditions change quickly and we can only monitor monthly.  Avoid going in the water during and immediately after rain–we have measured E. coli levels as high as 100,000 colonies per 100mL in Ioway Creek during storm events.

Last sampled August 18: 2/3 sites we tested on the South Skunk River upstream of Ames met the primary contact recreation standard.  Most other streams were not flowing.  At Story City, E. coli measured 240 colonies/100mL, just over the primary contact standard of 235 colonies/100 mL. 


Nitrate (a form of nitrogen) is a concern for the dead zone in the Gulf of Mexico. Prairie Rivers of Iowa and our partners have worked to promote practices in the Ioway Creek watershed that would reduce nitrogen and phosphorus loss. Before commercial fertilizers were introduced, nitrate levels in Iowa streams would have been less than 3 mg/L. While not relevant here, 10 mg/L is the drinking water standard.

 Current nitrate levels in Ioway Creek, from a sensor in the Iowa Water Quality Information System:

Nitrate levels have been low (below 5 mg/L) most of this year.  Unfortunately, we cannot attribute this to improved land stewardship–it’s the drought.  After heavy rains in mid-May, nitrate in Iowa Creek shot up above 15 mg/L, and gradually declined as tiles stopped flowing and river levels dropped.

Current nitrate levels in a drainage tile, near Kelley. Drainage systems provide a pathway for nitrogen to leach out of crop fields.