By Eric Compas
Testing our water quality arrays in Milwaukee
On 02, Aug 2015 | In Water quality | By Eric Compas
Mike, Karl, and I had our first big day with the water quality arrays. With everything working fairly smoothly, we headed to Milwaukee for a long day of kayaking. Our goal was to paddle up and down the Kinnickinnic, the Menominee, and Milwaukee Rivers starting from the Milwaukee County boat ramp at River Front (at the east side of the Kinnickinnic and Milwaukee confluence). We were hoping to see differences between the freshwater estuary areas of the lower river reaches to the more stream-dominated upper sections.
Starting around 10am, we paddled all day (mostly into a stiff wind) to cover almost all the ground we were hoping to. We stopped around 6pm after one of Mike’s arms fell off (well, nearly) and around 14 miles of paddling. Both Mike and Karl had units on their boats running all the time, so any stretch of water was sampled four times — a good opportunity to see how our units compared with themselves and each other.
Here’s a look at the raw data from our units starting with dissolved oxygen (DO). Click on the Legend and Layers icons in the upper right to view the legend and to switch between temperature, pH, dissolved oxygen, and electrical conductivity (I’d suggest using the link to full screen map to explore the data in detail). Also, once you’re zoomed in, you can click on any point for detailed sample information.
(Note that the map refreshes itself every minute — this is for when we’re collecting data in real time.)
The map shows considerable variability for most of the metrics we measured. The most significant changes — seen best in the temperature layer — is from the lake-influenced section of each “river” (colder water) to the stream-influenced section of each (warmer water). We were somewhat surprised, though, in how smooth this transition was, particularly in the greater surface flow from the Milwaukee and Menominee Rivers.
The second noticeable change was the increase in electrical conductivity (EC) as we moved upstream. Both the Kinnickinnic and Menominee Rivers showed increases in EC as we moved into surface-dominated waters (particularly when the river current was noticeable) indicating high amounts of dissolved solids in this largely urban watershed (more info at Milwaukee Riverkeepers and SEWRPC) (likely salts from roadways, runoff from Mitchell Field, nutrients from urban yards, and industrial waste water). The Kinnickinnic, in particular, had a region of very poor water quality with high EC values and very low DO (lowest reading of 0.97 mg/L!).
We also were very pleased with the consistency of the measurements we were getting from each unit. They both matched fairly well at initial glance with a couple of discrepancies along a couple stream reaches. We also encountered problems with our server as we paddled the Kinnickinnic, so there are a few gaps in this sample stretch (which is recorded on backup files on the phones that we haven’t retrieved yet).
Stay tuned — we have additional analysis planned to explorer values from both units and other ways of visualizing trends.