Monday 7/6 the Federal Energy Regulatory Commission (FERC) issued a letter to the City on the subject of violation of Run-of-the-River (ROR) operation at Barton Dam and the lack of inflow and outflow gauging that was required by the 1982 license. A plan to address these problems is required within 120 days. FERC rejected the long held practice of maintaining pond elevation as a proxy for ROR operation, noting many days of violation in a study period of December 2007 through February 2008. The incident that prompted the 2007/8 investigation was a hydro generation shutdown like the one that occurred today, where a power grid outage forced the hydro turbine to automatically shut off, leaving no utility power to operate the dam gates.

We’d already had two days this week of severe flow fluctuations – Wednesday City and contractor personnel made programming changes and did hoist maintenance, and that afternoon flow in the river dropped to very low levels twice. Thursday there were more fluctuations coinciding with gate and hydro operations at Barton.

This morning, the short, heavy downpour on the impervious surfaces of Ann Arbor sent a huge surge down Allen Creek, but at ~10am both Barton and Argo dams were flowing normally. Shortly thereafter the Barton turbine shut off and river flow dropped to ~50cfs for about two hours. As I write this the flow at the Ann Arbor gauge is 800 cfs above the previous steady flow (~500cfs) and still rising – probably due to the controller at Barton which is trying to get rid of the excess water stored there while the output was near zero.

As the city goes forward with plans to satisfy FERC, I hope they will consider adding automatic backup power at Barton (so an operator doesn’t have to go to the dam and start the backup generator to get control of the gates – this scenario has been reported to FERC at least twice before today). Also consider overall river effects during recovery from equipment/power failures – Maybe it’s better (ecologically and for human safety) to allow the pond levels to vary if downstream flows can be maintained at more natural levels rather than try to return to the target levels so quickly.

[search the FERC elibrary for docket p-3142]

An aspect of confusion here is that everyone keeps using the word “Dam” to describe two different features. One feature is extremely important, the other is less so.

Look at the the Sept 12, 2007 document. The DEQ official is very clear- at least to me. He states “The principal spillway and the main embankment of Argo Dam are in good condition. However, the headrace embankment is in poor condition”.

My translation: As DEQ describes, Argo Dam has two major parts. There is the main part that most everyone would consider the dam including the concrete and gates. This is the part that was completely reconstructed, or in dam-years is virtually new. It is the part that holds back the water thereby forming the embankment. It is also the part that is in good condition.

The second part is the headrace embankment. This is an appendage that has limited flow and is currently used by those that would like to paddle downstream (e.g. canoes). This is the part that needs attention. However it is also a part that is distinct from the rest of the dam system in that it can be shut off. In one sense there is a simple and low cost solution to this problem – use a weir board to close off the water in the raceway. If there is no water in the race then a failure of the headrace embankment isn’t an issue. The pond can stay. Of course keeping the water out of raceway would create a portage problem in that paddlers would have to find another way around the dam.

Any claim that the entire dam is failing distracts us from the much lower cost solutions.

The DEQ’s stating that the toe drains are failing is not the same as the “dam failing” statement made by Ms. Rubin in her AA News opinion piece. If the dam was actually failing I imagine the DEQ would force the city to take immediate action, instead of waiting for a plan to be presented by the city.

What I found especially interesting is that the DEQ letter also stated “and means of blocking flow into the raceway canal should be devised as soon as possible” Which is exactly in line with Joe O’Neal’s recommendation.

Did anyone notice over the past few weeks, a few canoeists and kayakers have needed rescue below Argo dam because of fast water issues, and that canoe renters were restricted to rowing only in Argo pond during some of these high water periods?

Argo pond provided a safe water venue during these high water events, something that will be lost if the dam is removed.

But Margaret, if, as you say, you don’t fully understand this issue, how do you judge what statements about it are “very, very, very misleading” and “NOT TRUE”?

Here’s what the chief of the DEQ’s Water Management Section said about Argo’s toe drains five years ago. “…the toe drains along the downstream side of the raceway canal embankment are failing. …The toe drain system should be repaired immediately…” (emphasis added. Full letter here.) The same letter notes that the DEQ has been telling the city to fix the problem since 2001, and to this day that hasn’t happened.

In other words, one of the state’s top dam safety officials says the same thing Rubin does. Arguing semantics, when both sides can make a decent case for the language they use, is picayune and irrelevant to the issues at hand. Whatever you call Argo’s condition, the DEQ takes it seriously enough that it’s ordered the city to do something about it, and no matter what word you use the city still has to repair the dam or take it out.