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HRWC’s Volunteer Army Descends on the Watershed!

On October 6, one-hundred twenty brave and intrepid volunteers spread across the Huron River watershed to collect benthic macroinvertebrates: the  crustaceans, insects, and mollusks that live in our creeks and rivers.  Typically, only the healthiest streams will have abundant and diverse populations.  Polluted streams and other streams that are heavily impacted by human activities will hold fewer of these creatures, and may only contain the most pollution tolerant types.  By watching the long-term trends of these populations, HRWC can tell where pollution may be becoming a problem and that helps direct HRWC’s time and effort.

See the full set of results from this past River Roundup event.

Dave Wilson samples Woods Creek midst a flurry of beautiful fall colors.

Overall watershed assessment

In order to get an overall sense of the health of the Huron River Watershed, HRWC samples macroinvertebrates from sixty-six 300 foot sections of the creeks and rivers.  The sampling sites have been selected to provide equal geographic representation from the various areas throughout the watershed.

In regards to their overall quality:

  • 2 sites are excellent (The best, most pristine areas)
  • 17 sites are good (Their macroinvertebrate populations are higher than we would expect based on the stream size, water temperature, and stream substrate).
  • 24 sites are fair (Their macroinvertebrate populations are slightly lower than we would expect based on the stream size, water temperature, and stream substrate)
  • 10 sites are poor (Pollution and other human impacts have severely damaged the macroinvertebrate populations at these sites)
  • 10 sites are new to the program and cannot be judged until more data is collected.

In regards to how the macroinvertebrate populations are changing at these sites:

  • 28 sites have remained largely unchanged since monitoring began on them
  • 15 sites have improved
  • 13 sites have declined
  • 10 sites are new to the program and cannot be judged until more data is collected.

Trend analysis shows tremendous variation by County

Three counties contain most of the Adopt-a-Stream sampling sites: Livingston, Oakland, and Washtenaw. When HRWC analyzed overall trends by county, a clear distinction appeared. The upstream counties, Oakland and Livingston, both showed roughly one third of sites declining, and no more than one tenth of sites improving. On the other hand, in Washtenaw County hardly any sites were declining and nearly half the sites were improving!

With results such as this, it is easy to start pointing fingers or consider the amount of money spent by these counties in improving water quality.  However, streams are complex systems, with many stressors, and this  analysis does not address the reasons for the differences we are seeing between the counties.

The two additional watershed counties, Wayne and Monroe, had too few study sites to detect overall trends.

Other noteworthy results

Drought causes influx of “marsh-loving” species into the Huron.

  • This year we saw a marked increase in marsh flies, marsh beetles, mosquitoes, and water treaders in the River Roundup samples. These critters prefer a habitat of slow-moving or stagnant water. This year’s drought has caused the flow in the Huron and it’s tributaries to slacken, and smaller regional pools, marshes, and wetlands to dry up. Whether these critters are moving in from dried-out-homes or flourishing in a sluggish creeks (or most likely both), the recent changes in weather patterns are certainly affecting the types of insects found in the Huron River.  (For comparison, last autumn’s heavy rains caused a corresponding drop in the prevalence of these species).

Good News at Mallet’s Creek: Restoration efforts look to be paying off!

  • Mallets Creek is one of the Huron’s most disturbed streams, earning an overall rating of poor. The creek is “flashy,” flooding dramatically with rainfall, which results in erosion and an influx of pollutants.  To address this problem, the City of Ann Arbor, the Washtenaw County Office of Water Resources Commissioner, and the Michigan Department of Environment Quality (DEQ) are collaborating on restoration efforts in the area. Ongoing projects include the creation of a 15 million gallon wet meadow, stream bank stabilization, and seeding of native vegetation. These efforts, along with homeowner-installed rain gardens and rain barrels, help decrease stormwater flashes.  Source: annarbor.com
  • This fall’s sampling of Mallet’s revealed encouraging improvement; An unusual increase in insect families were found.  For instance, volunteers collected 11 insect families compared to the recent average of 7.2. Species not seen at this site since 1996 were discovered, including the water boatman, finger-net caddisfly, and marsh beetle. While these improvements are not yet statistically significant, they are a great sign that local restoration projects are making a difference for our waterways.
Special note:  Volunteer Genevieve Leet contributed extensively to this data analysis and this blog. Thanks for your help, Genevieve!


2 Responses to “HRWC’s Volunteer Army Descends on the Watershed!”

  • Joan:

    Wonderful to see improvements in Washtenaw County creeks (and the River?)! The signs of improvement in Malletts Creek are especially heartening, showing effects of the many years of work by volunteers in that watershed. Which are the sites that had the improved diversity?

  • Paul:

    We only sampled one spot on Malletts this fall, at Chalmers. Given the results here, we’ll have to go to more of the Malletts sites in the spring.


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