By Phoebe Coburn
The ducks in Flat Creek are muddying the waters. Literally and figuratively.
In the literal sense, the water is looking a bit murky right now at the northern edge of Jackson where Flat Creek flows into town from the National Elk Refuge. Carlin Girard of Teton Conservation District explains that at this time of the year, migrating and overwintering waterfowl rooting around in the creek stir up sediment. He said swans are particularly good at agitating the streambed.
Flat Creek is a “spring creek,” meaning that it’s fed by a series of underground springs that keep the water flowing year-round. Because they’re more influenced by groundwater, during the winter months, spring creeks are a bit warmer than streams primarily fed by snowmelt. Spring creeks are also known for their clear water when they aren’t influenced by biological factors (ex. ducks) and watershed factors (ex. stormwater runoff). Though waterfowl may be partly responsible for Flat Creek’s turbid water right now, during the spring and summer, water diverted from the Gros Ventre into Flat Creek and runoff from the Town of Jackson make it appear muddy (aka turbid).
So why is it important to understand the turbidity of Flat Creek? The segment of Flat Creek running through town is considered “threatened” by the Wyoming Department of Environmental Quality due to stormwater runoff and habitat degradation. Turbidity is just one of many indicators of stream health, and a key part of understanding stormwater runoff. Turbidity is easy to measure, and therefore, it is regularly used to understand the variability and sources of sediment load in streams. Stormwater from streams and urban areas carries many contaminants, and the sediment it carries clogs the stream bed, inhibiting bugs and fish to carry out essential elements of their lifecycles. Lasting high levels of turbidity can also prevent sunlight penetrating the water, which can have a negative impact on aquatic plant life, aquatic insects, and fish. Some turbidity is natural, but understanding sediment loads, their relative magnitude and timing, and the sources of the sediment, can help us understand if sediment and stormwater runoff is being contributed by human causes. Understanding if and what human causes are harmful to the stream help us target improvement projects such as the Karns Meadow Stormwater Treatment Wetland.
So how are the ducks figuratively muddying the waters? There are two monitoring sites on Flat Creek that were installed in the fall of 2018 by USGS in cooperation with Teton Conservation District. The monitoring stations measure a number of parameters including temperature, discharge (CFS), and turbidity (check out the real-time here). However, turbidity is a tricky thing for an instrument to measure accurately. And our local waterfowl aren’t making it any easier right now. As they root around in the stream, they dislodge aquatic plants, which then flow downstream and can block up the turbidity monitors. To help address this, Carlin Girard and Chris Ellison from USGS check on the monitoring stations regularly and measure total suspended solids, which is the dry weight of all the suspended (not dissolved) particles in the water. Turbidity is a proxy for total suspended solids. So, by manually measuring total suspended solids, Carlin and Chris can build a model that will allow the real-time turbidity data being collected in Flat Creek to be converted to a suspended sediment concentration. Check out the video below of Chris and Carlin measuring total suspended solids in Flat Creek.
If you’re interested in helping out with this project (we could use a couple volunteers) or if you have questions, give Carlin a call at (307) 733-2110 or email him at carlin [at] tetonconservation.org.