Text reads: Chemistry and Flow Program Updates. Three round photos include images of people standing in waders in or nearby water with measuring tools in their hands.

April marked the start of the Chemistry and Flow Monitoring season. Many volunteers headed out into the field for the first time guided by leaders or HRWC staff. Volunteers began practicing and mastering the program’s many field methods on their first outing and within this first month collected 46 water samples, 5 filtrate samples, 115 real-time chemistry readings, and 139 velocity readings from the Huron River watershed and Downriver waterways.

PHOTO of the MONTH
New ADW volunteers, Chris, Sean, and Luca, learn to measure stream velocity across a section of Woods Creek on a cold and sleeting day.
Photo Credit: Larry Scheer, volunteer leader

Explore Our Water Chemistry Data

Explore Real-time Flow Data

Data Update: Water quality monitoring shows traces of winter de-icing salts

As the ground thaws in the spring, melting snow and rain helps replenish the groundwater and precipitation begins to run off across the land. This movement of water mobilizes chemicals such as nutrients, sediments, and especially de-icing salts that were applied to our roads, sidewalks, driveways, and parking lots over the winter. Much of these salts end up in our waterways and have been detected by our Chemistry and Flow Monitoring efforts.

Since our monitoring began, volunteers have been measuring conductivity, a general water quality indicator, that measures the amount of charged chemicals or ions in the water including salts (Figure 1). After observing consistently high conductivity values (medians > 850 µS/cm; Figure 1) in many Huron River tributaries as well as monitored tributaries of the Detroit River – Frank & Poet, Blakely, Brownstown, and Ecorse creeks – HRWC began investigating if salts might be contributing to these high conductivity values.

Figure 1. Representation of conductivity and chloride in streams. In our watershed chloride tends to increase with increasing conductivity. The scale shows the names of Huron River tributaries and Detroit River tributaries in order of increasing median conductivity value across all monitoring years. Conductivity is measured in units of millisiemens per centimeter.

Beginning in 2014, the samples collected by Chemistry and Flow Monitoring volunteers in Washtenaw County were analyzed for chloride by the Ann Arbor Water Treatment Plant. The data shows that conductivity and chloride values are correlated and chloride is high in urban streams. For example, the seasonal average (April – October) chloride concentrations in Honey, Allen, and Traver creeks are between approximately 120 – 200 mg/L and in Malletts, Millers, and Swift Run creeks are between approximately 300-500 mg/L most years. These values surpass the state’s newly established chloride standards for sustaining aquatic life (Aquatic Maximum Value > 320 mg/L and Final Chronic Value > 150 mg/L). In 2024, the state added these Huron River tributaries to the impaired waters list due to high chloride. Our monitoring program does not yet measure chloride  in Wayne County but the high conductivity records and calculated chloride estimates suggest many of those creeks are also impaired.

Read more about our findings in our Washtenaw and Wayne County Chemistry and Flow Monitoring Reports linked on our program page.

Site Spotlight: Millers Creek

Millers Creek is a small urban tributary in Ann Arbor that drains to the Middle Huron. The creek has notoriously flashy flows, or fast-moving water that causes the water level of the creek to quickly rise and fall after rain events, due to both the steep elevation gradient and percentage of impervious surfaces in the creekshed. Flashy flows have the potential to push more pollutants, like road salts, into the waterway and have led to extensive erosion.

These flashy flows likely contribute to the high conductivity and chloride values recorded in Millers Creek. Based on our data, Millers Creek has the highest conductivity and chloride values of all creeks monitored in the Middle Huron in Washtenaw County. Including data in Millers Creek from all monitoring years, the median conductivity is 2109 µS/cm and the median chloride value is 484 mg/L. Similarly high conductivity values have already been recorded in the creek this field season with a value of 2564 µS/cm on April 8th and 2478 µS/cm on April 19th. Thus with the implementation of new state chloride standards, Millers Creek is on the state’s impaired waters list due to chloride.

HRWC and our partners have completed multiple projects (e.g. implementation of green stormwater infrastructure) over the years that have helped to address flow flashiness and stabilize stream banks. HRWC has also developed a watershed management plan for the creekshed. Additional action is needed to fully address sedimentation, chloride, as well as pathogens, as measured by bacteria levels, in Millers Creek.

Discover more about Millers Creek

News

* = Articles that feature HRWC’s Chemistry and Flow Monitoring data!

Water Quality Tip: Hold the salt

Hold the salt! The best way to keep salt out of our streams during cold weather months is by shoveling snow and ice, early and often. If you occasionally need a de-icer for sidewalks and driveways, choose a product labeled “environmentally or eco-friendly.”

Learn more at www.hrwc.org/uselesssalt.

Want to learn more ways to be a good water steward?

Visit our Take Action Page.