Stormwater Sampling
This hardware is used to collect water samples from streams, ditches, or storm sewers after a heavy rain.
Prairie Rivers of Iowa, a non-profit in Ames, helps landowners and communities in central Iowa to improve water quality and wildlife habitat. We’ve been working closely with Story County, the City of Ames, and other partners to take a more comprehensive approach to water monitoring in local rivers and lakes.
Water quality can change quickly during and after a rainstorm. This video shows a creek near Ames High School, which receives water from a storm sewer system that drains North Grand Mall and several neighborhoods in northern Ames. The torrent of water is quite dramatic!
That water is carrying a lot of mud, fecal bacteria, and other pollutants (but not much nitrate). Earlier in the same month when we tested Ioway Creek, we measured 19 mg/L of sediment (low), 718 colonies of E. coli per 100 mL (exceeding the standard), and 0.1 mg/L of phosphorus (low). A bottle filled during this storm at the Ames High tributary had phosphorus 8x higher, sediment concentrations 18x higher, and E. coli 55x higher! Yuck!
Most people are more sensible than me and won’t run out in a downpour to collect water samples! When water in a creek or ditch rises above the lip of the sampler, these Nalgene storm samplers fill with water and seal shut, capturing a sample of the “first flush” of runoff generated by a storm. A volunteer can retrieve the bottle the next day for testing.
We’re hoping these samples can tell us where pollution from stormwater runoff is a biggest concern, make the case for practices that can treat runoff, and tell us whether ponds and other treatment practices are working. In urban areas, permeable pavement can reduce the amount of runoff generated in a downpour, while rain gardens and stormwater ponds can slow down water and let it soak into the ground. In rural areas, grassed waterways can stop gully erosion, while farm ponds and constructed wetlands can slow down and treat the water. Better soil health is a solution for runoff in both rural and urban settings. The City of Ames even has rebate programs for these kinds of practices.
-Dan Haug, Watershed Educator, Prairie Rivers of Iowa