Washtenaw County commissioners have voted to explore options – including possible legal action – to help set cleanup criteria for the carcinogen 1,4-dioxane in Michigan. In addition to its broader implications, the resolution is meant to address the 1,4 dioxane plume stemming from contaminants at the former Gelman Sciences plant in Scio Township, which is now closed. [.pdf of county resolution]
Ann Arbor city staff have been directed to explore actions available to the city, including meeting with the Michigan Dept. of Environmental Quality and petitioning the U.S. Environmental Protection Agency, to help set cleanup criteria for the carcinogen 1,4-dioxane in Michigan.
Map of Pall-Gelman 1,4-dioxane plume, by Washtenaw County. Black arrow added to indicate baseball field at West Park. The yellow region is the estimated plume area where the 1,4-dioxane concentration is greater than 1 ppb. That area encroaches well into the city of Ann Arbor and …
Four entities – including the federal Environmental Protection Agency and the local Huron River Watershed Council – have filed letters of objection with the state of Michigan to a project that would add a recreational section of whitewater along the Huron River, next to the new Argo Cascades.
Colin Smith, Ann Arbor’s parks and recreation manager, informed the park advisory commissioners about the opposition at PAC’s Sept. 18, 2012 meeting, describing the news as “not especially positive.” Other letters filed against the project were from the state Dept. of Natural Resources fisheries division and the U.S. Fish & Wildlife Service.
The project requires a permit from the Michigan Dept. of Environmental Quality (MDEQ) because it affects the Huron River, a state waterway. The project was originally approved by the Ann Arbor city council in 2010, as part of a larger effort that included building the Argo Dam bypass, which wrapped up earlier this year. Subsequent to that council approval, DTE Energy offered to pay for and oversee the whitewater aspect, to coordinate it with environmental remediation work that’s taking place on property it owns along that stretch of the river, just downstream of Argo Dam.
DTE is the applicant for the whitewater permit, although the company is working closely with the city on the project. The city is interested in acquiring the DTE property along the Huron after remediation is completed – and it’s hoped that the company might gift it to the city as a park.
Smith told PAC members that the EPA objection – because it comes from a federal environmental oversight agency – has triggered a process that might stop the project. The EPA filed its letter on Aug. 15. From that date, the MDEQ has 90 days [until Nov. 13] to resolve the EPA’s concerns with the applicant.
The EPA’s letter from Tinka Hyde, director of the agency’s water division, states that the project could significantly degrade the Huron River by inhibiting fish passage and increasing the water velocity, which in turn could affect sediment flow and degrade the stability of that section of the river. Another concern cited is that the project could constrain public use of the river. Because of these issues, the EPA believes the project does not comply with the federal Clean Water Act. [.pdf of EPA letter]
Similar concerns were cited in the other letters of objection. Additional issues raised include water quality concerns that could affect the health of those using the whitewater area, who might come in contact with E.coli in the river; and exacerbated flow problems during drought periods. [U.S. Fish & Wildlife Services letter] [DNR fisheries division letter and additional attachments] [HRWC letter]
The DNR fisheries letter – signed by Jeffery Braunscheidel, senior fisheries biologist – also alludes to the contentious “dam in/dam out” debate involving Argo Dam. Structures used to create the whitewater are in essence dams, he stated, and the division does not support new dam construction. “Planning should provide for a naturally functioning system below Argo Dam as history has made clear that, at some point in time, the Argo Dam will be modified or removed. Impediments should not be constructed in the river that the public will again be asked to address.”
But it’s the EPA’s objection that carries the most weight. If the EPA does not withdraw its objection and the MDEQ still decides to grant the permit, then DTE would also need to seek a permit from the U.S. Army Corps of Engineers before the project can move forward.
The full flow to the Argo Cascades was restored on Thursday, Aug. 2, 2012, according to a city of Ann Arbor press release, and the city is again renting kayaks and inner tubes for the series of pools and drops that offer an alternative boatable channel around the Argo Dam. Dry conditions had led the city to reduce the flow to the cascades during the previous week, on July 26.
Because the flow to the new recreational amenity was reduced, but not shut off completely last week, some confusion ensued about what measures, if any, the city had taken and why, and what the impact of those measures was.
At issue is the flow through two different channels – Argo Cascades on the one hand, and the stretch of the Huron River immediately below the Argo Dam on the other. The two channels are parallel and are separated by an earthen embankment, until they join together at a point just upstream of the Broadway bridge.
Downstream from that confluence, and near the Maiden Lane bridge, a U.S. Geological Survey gauge measures the total river flow.
Ostensibly, the planned reduction in flow to the cascades was to allow more water to flow through the dam-side channel, instead of passing through the Argo Cascades.
Based on a telephone interview with Molly Wade, unit manager for the city of Ann Arbor’s water treatment plant, here’s a summary description of what happened last week.
During the morning of July 26, city staff inserted a partial wooden stoplog at the entrance to the Argo Cascades. That evening, The Chronicle verified by visual inspection that the wooden stoplog was inserted in the slot. An intuitive “bathtub physics” expectation would have been to see no change in the gauge reading as a result of the partial stoplog insertion. That’s because whatever flow was previously going through the Argo Cascades would be expected automatically to flow through the dam-side channel.
That intuitive expectation was not met for two reasons. First, the Argo Dam is not a “spillover” dam, where the water flows over the top of the dam. So reducing the flow to the Argo Cascades would not “automatically” – in the bathtub physics sense – cause any additional flow through the dam-side channel. In order for the flow to increase through the Argo Dam, the dam’s gates – which are keyed to a pond-level gauge – would need to open wider.
So why didn’t the Argo Dam gates respond to what should have been a tendency for the Argo Pond level to increase? Ordinarily, you’d expect the Argo Dam gates would balance the lost flow downstream from the cascades with additional flow through the dam-side channel, thus maintaining the USGS gauge reading where it was – around 75 cfs (cubic feet per second). Instead, the gauge showed a drop to around 50 cfs.
That’s because upstream from Argo, at Barton Dam, the city staff was concurrently decreasing the opening to Barton Dam’s gates, in order to match the extremely low flow into Barton Pond. And reducing the flow at Barton ultimately reduced the flow to the river overall. A few days later, the pond levels at Argo and Barton rebounded, and the region enjoyed some, if limited, precipitation. And the flow rate as measured by the USGS Maiden Lane gauge started showing an incremental increase, to around 100 cfs.
By Friday, Aug. 3, the city of Ann Arbor had removed the partial stoplog at the cascades, and was back to renting kayaks for downstream trips through the pools and drops, all the way to the pond at Gallup Park.
The type of pattern for the increased flow in the Huron River, as measured by the USGS gauge, causes some continued concern by staff with the Michigan Dept. of Natural Resources and Dept. of Environmental Quality. The pattern is “saw-toothed,” which reflects the opening and closing of dam gates in response to a variation in pond levels.
After the jump, more detail is presented on last week’s events, and the pertinent legal constraints for dam operation. We also cover some related issues – concerning a permit that is currently being sought for construction of a whitewater area in the Huron River, near Argo Dam. That amenity is to be constructed in the dam-side channel at Argo, just upstream from the confluence of the river and the cascades.