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 extends outside the well prohibition zone (red border).

The vote was taken at the board’s Sept. 18, 2013 meeting with three of the nine commissioners absent: Felicia Brabec (D-District 4), Rolland Sizemore Jr. (D-District 5) and Ronnie Peterson (D-District 6).

Dan Smith (R-District 2) stated “present” during the vote, rather than voting for or against the resolution. After the meeting, corporation counsel Curt Hedger told The Chronicle that he’d be looking at the board rules to determine how Smith’s vote will be recorded. Hedger pointed out that the resolution needed five votes to pass, which it garnered.

The Ann Arbor city council passed a resolution on Sept. 3, 2013 related to the 1,4-dioxane issue. However, the city council resolution makes no mention of legal action.

In contrast, the resolution passed by county commissioners includes passage that:

…directs the County Administrator, Corporation Counsel and other appropriate county staff to work in collaboration with the County Water Resources Commissioner to explore other actions available to the County, including but not limited to legal action, meeting with and petitioning the MDEQ and EPA to aid in setting appropriate cleanup criteria for 1,4-dioxane in Michigan, including the Pall-Gelman plume and without site specific criteria for the Pall-Gelman plume and to cooperate with other local units of government to ensure protection of public health and the environment; …

The history of Gelman Sciences and its 1,4-dioxane contamination goes back 40 years. The company was based in Scio Township and later acquired by Pall Corp. The Michigan Dept. of Environmental Quality’s current 1,4-dioxane generic residential drinking water cleanup criterion was set at 85 parts per billion (ppb). But an EPA criterion set in 2010 was for 3.5 ppb.

The MDEQ was supposed to re-evaluate its own standards by December 2012, based on the EPA’s 2010 toxicological review. It missed that deadline, and is anticipated to miss a new deadline set for December 2013.

This brief was filed from the boardroom of the county administration building at 220 N. Main. A more detailed report will follow: [link]

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 extends outside the well prohibition zone (red border).

The goal would be to improve the cleanup standard for 1,4-dioxane by at least a factor of 30. The direction, which was given at the council’s Sept. 3, 2013 meeting, includes exploring actions related to the Pall-Gelman plume as well as without site specific criteria for the Pall-Gelman plume.

The council passed a resolution that was slightly different than the one originally on the agenda. The council’s deliberations lasted more than 30 minutes and focused on a possible postponement to make the resolution stronger. The motion to postpone, however, failed on a 4-5 vote on the 11-member council. Voting against postponement were Margie Teall (Ward 4), Chuck Warpehoski (Ward 5), Mike Anglin (Ward 5), Sabra Briere (Ward 1) and mayor John Hieftje. Councilmembers Jane Lumm (Ward 2) and Marcia Higgins (Ward 4) were absent. [.pdf of resolution as amended and approved] The resolution was sponsored by Briere, Warpehoski and Hieftje.

The history of Gelman Sciences, which caused the 1,4-dioxane contamination, goes back 40 years. The company was based in Scio Township and later acquired by Pall Corp. The MDEQ’s current 1,4-dioxane generic residential drinking water cleanup criterion was set at 85 parts per billion (ppb). But an EPA criterion set in 2010 was for 3.5 ppb.

The MDEQ was supposed to re-evaluate its own standards by December 2012, based on the EPA’s 2010 toxicological review. It missed that deadline, and according to the council’s resolution, is anticipated to miss a new deadline set for a year later in December 2013.

This brief was filed from the city council’s chambers on the second floor of city hall, located at 301 E. Huron. A more detailed report will follow: [link]

A view looking upstream at the Huron River from the Broadway Bridge, toward the section of the proposed whitewater feature. On the left is environmental remediation work on the DTE/MichCon property. (Photo by D. Askins.)

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.

At PAC’s Sept. 18 meeting, Smith told commissioners that the EPA letter was “somewhat surprising.” It’s unusual for the federal agency to weigh in on a relatively small project like this. He did not speculate on why the EPA got involved, but said that staff with the city and DTE had met with MDEQ earlier in the day to make sure they understood the objections. The design had already been modified to respond to concerns that the MDEQ had previously raised, he said, adding that the staff will try to do everything they can to move the project forward.

The objections from the Huron River Watershed Council are less surprising. The Ann Arbor-based nonprofit, which works to protect and improve the Huron River and its tributaries, was an advocate for removing the Argo Dam when that issue was debated by city council in 2009. [Background on that topic is included in Chronicle coverage: "Planning Group Revisits Huron River Report."]

Schematic showing location of the planned whitewater amenity in the Huron River, upstream from where the Argo Cascades enters into the river.  (Image links to .pdf of slide presentation made at a March 12, 2012 Ann Arbor city council working session, with higher resolution images.)

Part of the context for the dam in/dam out question related to MDEQ’s concerns about toe drains in the earthen embankment adjacent to the concrete and steel dam, which separates the headrace from the river. The dispute with the state over how to deal with the toe drains at Argo Dam was ultimately resolved when the city council approved a $1,168,170 project at its Nov. 15, 2010 meeting to build a bypass that replaced the headrace and eliminated the portage previously required by canoeists and kayakers. That project – the Argo Cascades – was finished earlier this year.

The $1.168 million included $180,000 for the whitewater feature, to be designed by Gary Lacy of Boulder, Colo., and built by TSP Environmental, a Livonia firm – the team that designed and built the Argo Cascades.

In mid-2011, DTE proposed paying for the project but delaying its construction until after the company finished remediating the land next to the Huron River immediately across from the cascades, on the south side of the river. DTE had hoped to secure a permit for the whitewater project this summer. It has already begun environmental remediation work at the site.

The letter of objection from HRWC is signed by its executive director, Laura Rubin, and deputy director Elizabeth Riggs. The letter raises a range of concerns, including the project’s affect on flow rate. From the letter:

The documented flow problems at Argo Dam and the Argo Cascades … during a low flow period highlight, at best, the challenges of multiple-use resource management and, at worst, the desiccation of Michigan rivers when recreational use is prioritized at the expense of other uses, namely shared natural resources. This problem will be exacerbated if the proposed structures are built . Moreover, a likely unintended consequence of the structures being built will be City leaders and staff finding they have to choose one whitewater feature over the other when flows are insufficient to keep both recreation features open.

For Chronicle coverage of the flow-rate issue, see ”How Low Can Argo Flow Go?”

The majority of concerns cited in the HRWC letter relate to potential problems caused by the installation of two structures in the river that are necessary to create the whitewater effect. From the letter:

1. Whitewater structures can impact stream hydrology and hydraulics. Low-flow dams/weirs incorporated into certain whitewater structures reduce channel width by up to 90 percent, creating velocity barriers to organism passage and potentially increasing shear stress on down stream bed and banks.

2. These narrow weirs can create stagnant pools that strand aquatic organisms and raise water temperature.

3. Many whitewater structures are ” low head” dams and have similar effects of a low head dam. Dams interfere with sediment transport by creating sediment deposition zones in the pools between structures, which in turn may eliminate preferred fish habitat, interfere with down stream drifting of macroinvertebrates, and lower dissolved oxygen concentrations. Whitewater structures may also interfere with the transport of small and large organic materials. Organic material transport plays a crucial role in stream health, from fallen leaves that are food for macroinvertebrates to large woody debris that provides sediment retention in stream channels and cover for fish.

4. Whitewater structures can create passage barriers or stranding hazards for fish and other aquatic organisms due to a combination of high water velocities, inadequate water depths, high vertical drops, turbulence, and lack of space for resting cover. The measured velocities over current white water structures are greater than the known velocity capabilities of most of the native fish species present in Michigan rivers.

5. The porous streambed and banks in rivers are essential habitat for fish and macroinvertebrates – macroinvertebrates such as the state threatened freshwater mussel species that was positively identified in this section of the Huron River on July 25, 2012 by ecologists with the University of Michigan and HRWC. Additionally, this habitat functions to exchange water between the ground and river, assist in nutrient and carbon assimilation, and moderate river temperatures. Grouted whitewater structures eliminate habitats in the spaces between rocks and block the interplay between the river, land, and groundwater.

6. The proposed whitewater structures include large rocks, benches, terraces, or viewing platforms, which can displace riparian vegetation. Riparian vegetation contributes to the health of the river by providing shade, bank stabilization, large woody debris, and habitat for aquatic and terrestrial wildlife. Riparian vegetation also improves water quality by removing excess nutrients, preventing sedimentation from bank erosion, and lowering water temperature. Whitewater structures also increase the amount of rock in the stream or riparian corridor, which can increase water temperatures.

Upon receiving news from Smith about the letters of objection, park commissioners had only a few clarificational questions, though several members spoke to him about it immediately after the meeting adjourned. PAC had previously recommended approval of the whitewater feature, as part of the overall dam bypass project. That vote took place in October 2010 – there has been considerable turnover on the commission since that time.

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View looking north through the entrance to the Argo Cascades on Aug. 3, 2012. (Photos by the writer.)

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.

Insertion of the Cascades Stoplog

By way of basic geographical background, the city of Ann Arbor maintains a dam at Barton Pond that generates hydroelectric power and falls under the regulatory jurisdiction of the Federal Energy Regulatory Commission (FERC).

Huron River as it flows through the city of Ann Arbor.

Based on a 2009 letter from FERC to the city of Ann Arbor, the city operates Barton Dam under a May 4, 1982 FERC order that requires it to be operated in an “instantaneous run-of-river mode.” That is, the flow on the downstream side of the dam should exactly match the flow into the pond on the upstream side.

The FERC order requires implementation of a Michigan Dept. of Natural Resources (MDNR) requirement – maintaining either a minimum flow of 100 cfs or the amount that is flowing into Barton Pond, whichever is less.

Barton Pond is also the primary source of the city’s drinking water.

Argo Dam is about two miles downstream from Barton. It’s not regulated by FERC, because it does not generate any hydroelectric power. The city uses Argo Pond as a recreational amenity – maintaining a canoe livery there, renting boats for pond paddling as well as for trips down the Huron River to the pond at Gallup Park.

Previously the Argo-Gallup river trip required a portage. Paddlers would start from Argo Pond, navigate a short distance to the entrance to a headrace leading around the dam, then paddle along the headrace to a point where it spilled back into the river. That spillway was not boatable, and required the portage. Construction of the Argo Cascades, which opened for the first time this season, eliminates the need for a portage, and addressed the long, drawn out concern that the dam safety unit of Michigan’s Dept. of Environmental Quality had raised about the earthen berm separating the two channels.

On Wednesday, July 25,  Sumedh Bahl – the city of Ann Arbor’s community services area administrator – indicated in an email the imminent closing of Argo Cascades the following day:

To comply with the Federal Energy Regulatory Commission and the MDNR minimum flow requirements across Barton and Argo dams, the low flow in the river has necessitated closing Argo Cascades. Presently it is planned to stop the flow through Cascades tomorrow [July 26] morning. Staff will continue to monitor river flows and the flow will be restored to the Cascades when flow in the river improves.

Based on the wording in Bahl’s email, the expectation was that the flow to the cascades would stop.

Argo Cascades partial stoplog. Photo from evening of July 26, 2012.

However, mid-morning of July 26, Cheryl Saam, manager of the city’s canoe liveries, told The Chronicle that the cascades’ flow had been reduced, not stopped completely, by inserting a partial stoplog. The wooden partial stoplog was visible from the bridge over the inlet to the cascades.

The continued flow through the cascades prompted skepticism by some about whether the city had undertaken any measures to reduce the flow through the cascades. Paul Christensen, who’s active in the Huron River Fly Fishing Club, shot some video and posted it online, highlighting the visual contrast between the flow in the two channels.

While a visual assessment of the two flows might depend on subjective judgment, the USGS gauge showed an objective change – right around the time of 10:30 a.m. when Saam had indicated the city had inserted the wooden stoplog. If the point of inserting the stoplog was to cause more water to flow through the dam, instead of down the cascades, then the expected effect would not have been a reduction in the total river flow.

Simultaneous Action at Barton Dam

But the gauge showed a drop from about 75 cfs to around 50 cfs in that timeframe. As Molly Wade explained to The Chronicle, insertion of the cascades stoplog was not the only river flow-related activity that occurred. At the same time, city staff were reducing the opening in the upstream Barton Dam’s gates. It’s that reduction in the total river flow that the gauge reflected.

In previous weeks, the Barton Dam gates had been open to the minimum automatic setting, according to Wade, which is 100 cfs. When the Barton Pond levels began to drop, that meant less than 100 cfs was coming into Barton Pond from upstream. So eventually, staff undertook to manually reduce Barton Dam’s gates on July 26 – to 50 cfs. That’s 10 cfs less than the designed flow for the Argo Cascades. So that warranted a reduction to the Argo Cascades flow.

Huron River discharge rate from July 26 through Aug. 2, 2012.

Wade’s explanation was consistent with the one that parks and recreation manager Colin Smith passed along via email to Ward 1 councilmember Sabra Briere: “The city responded by adjusting the gate at Barton further downward, allowing only what was flowing in the river to pass. The city also lowered the flow to the Cascades to allow more water over the gates of Argo dam. However, because the Barton gates were lowered to match the river flow, the overall flow through Argo concurrently dropped to match the river flow.”

National Weather Service precipitation map for 7-day period from July 27 through Aug. 2. Washtenaw County is outlined in red. Dark blue regions received up to 0.5 inches of rain. Light blue indicates up to 0.25 inch of rain.

In subsequent days, the total river flow began to rebound slightly, as some limited precipitation fell.

By Friday, Aug. 3, the city had removed the stoplog at the Argo Cascades, and boat rentals had resumed.

Starting around Saturday, July 25, the type of pattern shown by the USGS gauge measurements is “spikey” or “saw-toothed.” That reflects the response of the Argo Dam gates to pond levels at Argo, which are affected by the flow through Barton Dam. Unevenness of flow at Barton Dam has drawn scrutiny from FERC in the recent past.

But the unevenness of flow has also been of general concern to state officials.

When The Chronicle spoke by phone with Chris Freiburger of the Michigan Dept. of Natural Resources fisheries division, he indicated two potential areas of concern.

One was the unevenness of the flow – which does not appear to mimic natural, more gradual fluctuations in river flow. That unevenness of flow could have a negative impact on aquatic life in the dam-side channel.

Wade noted that some options for improving the evenness of the flow would require conversation with the MDEQ. She ventured that one possible approach would be to try to get finer control over the gates at Barton. For example, if only one gate opened, instead of operating in tandem, that would increase precision by a factor of two.

The other concern is the percentage split of the flow between the Argo Cascades and the dam-side channel. According to Wade, the city is using 85 cfs as the benchmark gauge level. That’s a number that comes from the sum of 60 cfs for the design flow rate of the cascades, and 25 cfs – the minimum opening (other than zero) for the Ago Dam gates. When the total flow drops below 85 cfs, that’s when a reduction of flow to the cascades would be undertaken, Wade said. But Freiburger observed that a 25-60 split doesn’t follow the typical pattern for diverting a smaller fraction of a flow around a dam.

Competing Flow: Reasonable Use, Aquatic Life

The Huron River Watershed Council has also expressed concern about the relative amount of water that gets put through the Argo Dam-side channel, based on the city’s protocol. In an email to The Chronicle, Elizabeth Riggs, deputy director of the HRWC, indicated a concern that the dam-side channel is drying up – a concern that was heightened because two live state-protected freshwater mussels were positively identified within that stretch of the river.

But in conversation with The Chronicle, Wade pointed out that the old configuration of the headrace – the precursor to the Argo Cascades – shunted roughly the same amount of flow around the Argo Dam. What’s different this year is that the city is actually regulating that flow for the benefit of the dam-side channel. The city didn’t do that in previous years, she noted.

In a telephone interview with James Sallee of the Michigan Dept. of Environmental Quality water resources division, he allowed that Wade likely has a reasonable point in comparing the cascades to the old headrace – in that the cross-sectional area of the entrance to the cascades is the same as the old headrace. He noted that the publicity around  the new recreational focus of the cascades meant that the competition for water flow through the two channels was now highlighted.

Given that aquatic life will have by now taken hold in the cascades, the interests of that aquatic life has to be balanced against the aquatic life in the  dam-side river channel, Sallee said. [The Chronicle noted there were some anglers fishing the Argo Cascades when it was closed to city-rented boats – but those anglers did not appear to be having success.]

Another set of competing interests is types of recreational use. The choice between allowing water flow through the cascades compared to the dam-side river channel could be seen as a choice between anglers – who fish the dam-side channel – and boaters, who use the cascades. Under doctrines set forth in “Public Rights on Michigan Waters,” a ”reasonable use” of the water is supposed to be assured, which would presumably apply to both types of recreation.

That potential conflict in types of use is one of several factors that Sallee will be weighing in an upcoming decision he’ll be making about issuing a permit to MichCon for construction of a whitewater amenity in the dam-side river channel. It was originally supposed to be part of the city’s Argo Cascades project, but MichCon offered to pay for the whitewater structures, in connection with its environmental cleanup of land on the opposite side of the Huron River, across from the cascades.

The idea is that kayakers will descend through the Argo Cascades, and when entering the Huron River will paddle upstream a short distance to the whitewater feature. One factor that Sallee said he’ll weigh is the potential conflict in recreational use between anglers and boaters.

On July 25, a public hearing was held on the MDEQ permit for the whitewater amenity construction. Sallee told The Chronicle that he expects to make a decision on the issuance of a permit by Sept. 21, or possibly sooner.

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