Water Quality Monitoring in Story County
Understanding water quality in Story County lakes and rivers is a big job with many components and involving many partners:
2021 Annual Report
Key findings from the 2021 monitoring season are shown below. 2021 was a very dry year, but we learned some important lessons about how to collect and interpret water quality data to better account for the weather and reveal underlying trends in land management. Click here to download the 39-page report.
Recreation and Waterborne Illnesses
E. coli bacteria was usually low at swimming beaches and parts of the South Skunk River, but high in most creeks. We can narrow down likely sources of contamination by checking whether bacteria is highest during low flows or high flows.
Gulf Hypoxia and Nutrient Losses
This year was too dry to have much influence on Gulf Hypoxia. Focusing on normal-to-wet periods will help to identify hot spots where conservation practices are needed and evaluate whether conservation practices are working.
Nutrient Enrichment and Algae Blooms in Lakes and Streams
During dry conditions, the highest nutrient levels are below wastewater treatment plants.
Fish and the Insects They Eat
Low dissolved oxygen is harming invertebrates in some streams. Effluent from wastewater treatment plants could be a factor, but some patterns are still unexplained.
Story County Water Monitoring & Interpretation Plan, 2021-2030
Prairie Rivers partnered with Story County and 8 other organizations to develop a ten-year Water Quality Monitoring & Interpretation Plan for Story County. Regular communication between the various groups testing water helps avoid duplication and leads to new opportunities to improve water quality. Planning for how data can be used over the long-term ensures that we get the most value from our time and effort. Read the plan here.
- Prairie Rivers of Iowa
- Story County Conservation
- City of Ames
- City of Nevada
- City of Gilbert
- City of Huxley
- Story County Soil & Water Conservation District
- ISU Leopold Center for Sustainable Agriculture
- Izaak Walton League of America
- Story County Community Foundation
How’s the water? Click here to see real-time data from water quality sensors and gages, as well as our latest summaries. Sensors are maintained by USGS, University of Iowa’s IIHR, the USGS, and the USDA. Sensors may be offline during the winter.
Story County Conservation has assembled water testing kits that it is making available for volunteers to do regular monitoring of streams around the county. Find out about the monitoring program and sign up here.
Prairie Rivers has been continuing the long tradition of organizing volunteer “watershed snapshot” events in May and October. We also make supplies available to local science teachers.
Staff from Prairie Rivers, the City of Ames, and volunteers collect monthly water samples from 15 sites around the county which the City of Ames Water and Pollution Control Laboratory tests for nutrients, sediment, and bacteria. Results are posted here and updated within two weeks of sampling.
We’re partnering with Dr. Jacob Petrich from the ISU Chemistry Department to narrow down sources of fecal bacteria contamination by using light to test for flourescent whitening compounds found in laundry detergents. So far, we’ve been able to detect the compounds at low levels, but we’re also picking up some confounding signals from other things that fluoresce in the same range. There are some additional tests that Dr. Petrich thinks can distinguish them.
We’re using storm samplers to get a better understanding of polluted runoff. Water quality can change dramatically after heavy rain.
Analyzing the Data
Is water quality improving? That’s a harder question to answer than you might think. Our Watershed Educator, Dan Haug, has been learning the programming language R and statistics and trying to translate the findings for the rest of us: i.e. “If you sample on Mondays, you might get a different result than if you sample on Fridays.”
We presented a poster on this concept (Minimum Detectable Change) at the 2021 Iowa Water Conference.
It’s also a common topic on our blog:
By understanding the margins of error associated with water quality averages, we ensure there’s not a mismatch between the size of changes we can detect and the size of changes we would expect from conservation projects. We can improve our ability to detect trends by changing the monitoring setup or analysis. Place-to-place rather than year-to-year comparisons are less susceptible to this kind of error, though not fool-proof.
Our goal is to make sure our conclusions are robust and relevant to our stakeholders.