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What’s Causing Those Crazy River Fluctuations in Ann Arbor?

As many of you know, the USGS stream gauge at Wall Street in Ann Arbor has been showing some alarming river fluctuations in the past years. These wild swings in flow, represented by rapid increases to high flows in a matter of minutes, followed by a similarly rapid drop to almost no flow in some downstream areas are likely having a significant impact on fish and other aquatic wildlife in the river.  The fluctuations are being influenced by upstream dam operations and Allens Creek.  I talked to Sumedh Bahl, City of Ann Arbor engineer in charge of dam operations, about these fluctuations in a meeting a few weeks ago.  Chris Freiburger from the MDNRE was also present.  Sumedh and his staff are trying to determine the main cause of these wild swings—Barton and Argo Dam operations, or Allens Creek.  Ann Arbor is upgrading their equipment at Barton Dam and installing a back-up generator.  The city also is working with the USGS on calibrating the dam mechanisms to improve responsiveness to changes in river flow.

HRWC is hosting a meeting on Tuesday, June 22nd at 7:00 PM at the NEW Center, 1100 N. Main St. in Ann Arbor to talk about the steps the city is taking to try to reduce dam-induced river level fluctuations and possible causes of the river fluctuations.   I hope this will be a time to discuss how we can minimize these severe river fluctuations and understand the causes better.  Call Laura at 734.769.5123 x606 if you have any questions.

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6 Responses to “What’s Causing Those Crazy River Fluctuations in Ann Arbor?”

  • Laura –

    There’s a further story at AnnArbor.com at

    http://www.annarbor.com/news/flood-watch-issued-starting-this-evening/

    with accounts of the details of this issue, with special note to its impact on recreational uses of the river downstream from Argo.

    I am amazed that there is no flow metering on Allen Creek, and no flow metering or water level logging upstream of Barton Dam.

    If you look at other creeks in the area you can finally start to see the impact of the latest storm on them. Mallett’s Creek was carrying 2000 cfs in the most recent deluge – that’s a Huron River worth of water for a few hours on a stream that usually gets just a relative trickle.

  • Russ Miller:

    Ed,
    There is (or was) a gauge on Allen’s Creek operated I believe by County Water Resources.

    http://www.ewashtenaw.org/government/drain_commissioner/dc_webWaterQuality/ac/news/090607

    It’s noteworthy that we haven’t seen any of the really deep reductions in flow that are often associated with lightning storms and power outages since the new 50kW generator was installed at the Barton powerhouse.

  • Laura Rubin:

    Thanks Ed. Yes there is a pressure transducer in Allens Creek but the data has not been collected off it in a while. The city is working on it. Russ, I was told the back-up generator at Barton wasn’t going on-line until the end of June. Something we can ask Sumedh about.

  • Russ Miller:

    Hi Laura,

    Good info. Thanks for setting up the meeting.

  • http://bit.ly/LowFlowHuron — HRWC can clearly see fluctuation in river flow and impact – geotagged photos

  • Rork Kuick:

    I was writing the drain commissioner in 1988, incensed that fluctuations in flow in early July, when the river was averaging only 20 cfs, were stranding fish and other organisms. Fluctuations at low water as percent of flow were huge compared to what we see at high flows (the power failures scenario is a separate type of failure).

    Just recently I read this from the FERC about Barton dam: “Pursuant to article 2, the exemption order requires you to implement a Michigan Department of Natural Resources’ (MDNR) requirement to provide a minimum flow of 100 cubic feet per second (cfs) or inflow to the impoundment, whichever is less. By letter dated December 24, 1981, the U.S. Fish and Wildlife Service (FWS) requires you to provide stream gaging stations immediately upstream and downstream of the project to verify instantaneous run-of-river operations.”
    Yes, that says 1981.
    (That’s from searching http://elibrary.ferc.gov/idmws/search/fercadvsearch.asp with docket “P-3142″. I think gaging is a typo in the original, but funny.)

    Questions:
    1) How can it be that the requirements for gauges can have been left unfulfilled for that long? It’s almost 30 years!
    2) How is removing water from the impoundment affected by this requirement? One part of my grumping in 1988 was because Ann Arbor wasn’t restricting water use very seriously, even though the situation seemed serious to me.
    3) How do people measure how much water the city is removing from the impoundment?
    4) Are there other requirements that come with operating that dam that are being ignored (like public access)? Where are the pertinent documents?
    5) What do people now think about the design of that dam?


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