Posts Tagged ‘Dams’
On a crisp Thursday morning last week, as the sun rose over the pond formed by Argo Dam in Ann Arbor, 25 owners and operators of small dams within the Huron River watershed gathered to discuss their management and responsibilities for the dams.
Here are some of the highlights:
Elizabeth Riggs provided background information and statistics about dams in the watershed, in Michigan and around the nation. The majority of dams in the watershed are more than 40 years old, which presents a significant maintenance issue across the watershed as these dams may be approaching (or passed!) their design life. Elizabeth also discussed the growing national trend of dam removal. She indicated that removal can be 3 to 5 times less expensive than dam reconstruction, and funding is available for removal, but not reconstruction.
Luke Trumble, environmental engineer with the Hydrologic Studies and Dam Safety Unit of MDEQ, spoke to the group about the state’s regulation of dams and how it impacts dam owners. He emphasized liabilities associated with dams and the importance of inspection for dam safety. He indicated that owners of high-hazard dams are about 95% compliant with inspection and maintenance regulations. MDEQ inspects state-owned and municipally-owned dams upon request. Private owners must hire private, licensed engineers.
Shawn Middleton, engineer with the Spicer Group, presented on dam inspection and maintenance considerations and the economics of dam management. He highlighted observable evidence of dam deterioration, what to do about it, and how to quantify and minimize cost. One interesting point of discussion was that most of the older dams were not designed for the flood sizes that can be expected in the near future. For example, storms have caused dam failure in western parts of the state in recent years.
Following the presentations, Laura Rubin facilitated a discussion with the attendees and speakers on topics such as restoring river systems following a long period as a dammed system; dam ownership and transfer; and hydropower cost vs. revenue. Cost/benefit analysis in Michigan is showing that converting to hydropower is a liability rather than a benefit financially.
Leading up to the seminar, HRWC has worked to inventory the dams in the watershed and collect information about the structures, their ponds, owners and management. Dam owners and operators were surveyed to update information in the dam database. During this process, more dams, many which are too small to be regulated by the state, were discovered. The large dam operators on the river mainstem recently formed an informal association to establish communication and share information. The smaller dam owners were invited to last Thursday’s seminar.
Presentations and Links of Interest are now available at www.hrwc.org/events/past-seminars.
Climate adaptation is any action taken that reduces the vulnerability of natural communities and the built environment to the impacts of climate change. For example, if we are going to get larger storms, what do we need to do to our stormwater practices and infrastructure to reduce the chances of flooding or pipe or dam failure? If warmer air temperatures mean we are more susceptible to a new forest pest or pathogen, what do we do to reduce tree loss? These are some of the questions we are considering, along with water resource professionals from throughout the watershed, in our Making Climate Resilient Communities project.
We are not alone in our efforts to adapt to changes in climate. There are communities, agencies and organizations throughout the Great Lakes Region that are engaged in efforts to determine courses of action in response to climate change. Those of us who are working in this arena are pioneering a new field and can serve as a resource to others.
Recently, EcoAdapt, an organization focused on facilitating climate adaptation, released a report: The State of Climate Change Adaptation in the Great Lakes Region. The report provides an overview of climate change in the region, shares the results of a survey to water resource professionals capturing adaptation activities and reflects on common challenges and opportunities to push the needle forward on climate adaptation.
HRWC’s Climate Resilient Communities and Saving Water Saves Energy projects stand proudly among the 57 case studies highlighted in the report (pg 94). You will also find other examples from our watershed including the efforts of the City of Ann Arbor (pg 103) and the Great Lakes Adaptation Assessment for Cities project that has selected Ann Arbor as one of it’s assessment cities (pg 142). This report, along with many other adaptation resources can be found on CAKE (Climate Adaptation Knowledge Exchange) website.
We glimpse the future under a changed climate
Weeks of air temperatures above 90 degrees F have lots of people talking about extreme weather and the role of climate change. Such extreme heat yields myriad human and environmental effects. A previously unexplored effect is the stress that court-established water levels on lakes will have on the Huron River system under drought conditions that are projected by climate scientists to occur with greater frequency over the next 30-50 years.
State laws at odds
Michigan law prohibits reduced river flows under Section 324.301 of the 1994 Natural Resource and Environmental Protection Act. The section states that diminishing an inland lake or stream is prohibited without a permit. ”Diminish” means to reduce flows to a creek, as happens when gates of a lake level control structure are closed.
However, read a bit further and you’ll see that Michigan law allows for reduced river flow under Section 324.307. Under this law, lake residents are allowed to obtain a regulated lake level by building a lake-level control structure that maintains a lake’s water level while reducing flow to downstream lakes and rivers. Lake residents are motivated to pursue lake levels to make it easier to boat, recreate in the lake, and build docks that they can reliably use despite changes in weather conditions. Many lakes in the watershed, including in-line lakes that are impoundments of the Huron River, have court-ordered lake levels.
Lake residents are able to obtain these designations through a process with the Michigan Department of Environmental Quality (DEQ). Once a lake level is set by a judge, then the county government (often the Drain or Water Resources Commissioner) is responsible for altering the outflow of the water from these lakes via structures so that the the lake is able to maintain a constant depth. Dams are one type of structure used to control flows. Other structures like the one pictured above also are present in the watershed.
Typically, though not always, the DEQ gives section 307 precedence over section 301, meaning that permitted lake-control structures are allowed to diminish the downstream lake or stream in order to maintain their lake levels.
Keeping a lake level in drought conditions
Maintaining a court-ordered lake level may go unnoticed during periods of normal or wet weather. But this manipulation of a natural system has the potential to stress the ecology of the lake during drought periods. Since the county is obligated to maintain a certain water level it is possible that they would need to “hoard” incoming water and only allow reduced flow — or even no flow — downstream. The graphics below show a simple input and output system to illustrate the issue.
Under typical flow conditions, the amount of water entering a lake will equal the amount of water leaving the lake, plus any additions from rain, and minus any water lost through evaporation. Under drought conditions, the amount of water entering the lake is already reduced from low stream flows, no additional input is provided from rain, and the amount of evaporation can be significantly high. As a result, it is possible that the county would have to close the gates altogether to maintain the lake’s court-ordered water level, and no water or very reduced flows will reach downstream to keep the fish alive or provide water to the next lake or river section downstream.
How can the situation be improved?
For the waterfront resident
Given the current hot and dry conditions in southeastern Michigan, waterfront residents likely are seeing reduced water flow especially if living downstream of a lake with a court-mandated lake level. Understandably, this imbalance of “water power” may feel unfair and residents could be looking for a fast and easy solution to secure more water for their section of the river or lake. Such a solution doesn’t exist. Aggrieved residents have sought justice through our legal system. Typically, these cases are eventually dropped since droughts end and rain, and consequently higher water flow, mute the problem.
Yet, droughts are predicted to become more common and more severe over the next several decades, and we may see a resurgence of court cases.
A measure of relief may be found in the operation of the structures. Some lakes have an ungated pipe or dam bypass that drains downstream, so that some amount of water is always flowing downstream, even when the dam’s gates are completely closed. However, such a bypass is not a requirement in obtaining the establishing a legal lake level. Building this in a requirement would be an important and wonderful safeguard to ensure that some level of water is always going downstream.
And for the river
The DEQ has the responsibility to examine the problem with stream flow as it relates to drought and mandated lake levels. In particular, giving the priority of maintaining lake levels over allowing for run-of-the-river flows is dangerous for the survival of downstream ecosystems when facing drought situations.
After speaking with DEQ staff, I am happy to report that the issue is on their radar and under consideration. HRWC will keep an eye on this complex issue at the state level, and work with local partners to find workable solutions to this increasingly urgent problem.
With the huge rain last week and the flood warnings, I visited the U.S. Geologic Survey’s (USGS) real-time stream flow gages on the river to see how the river reacted . In the Huron, we have 4 permanent USGS gages in the river that measure stream flow constantly. The sites are the Huron River near New Hudson, the Huron River near Hamburg, Mill Creek in Dexter, and Wall Street in Ann Arbor. These gages allow us to see how the river responds to rain and snowmelt. A slow, gradual rate of stream flow increase (and corresponding decrease) is indicative of a more natural and higher quality river with natural areas for infiltration. An erratic rate of increase (and decrease) is indicative of a more impacted and degraded river where pavement and pipes prevail.
The USGS also has a map of real-time streamflow compared to historical streamflow for the day of the year for Michigan. Only one of the sites on the Huron, that farthest up on the system, is “normal”, two other sites being “above normal” and the stream flow at Wall St. in Ann Arbor is “much above normal”. Normal flow patterns change due to increased impervious surfaces such as roads and rooftops, a loss of natural areas such as wetlands, floodplains, and forests, and dams that alter the natural flow of the river. There may also be a regional variation in annual rain amounts.
In this and coming decades, meteorologists project more intense storms for Michigan, warming and cooling periods in close succession, and an overall warming trend. HRWC is working hard to restore the river and creeks to a more natural and healthy system so they can respond to the “weird” weather–taking up and storing more rain water in storms, slowly releasing the water in to the groundwater, creeks, and rivers over time to keep steady flows in drier weather–overall, allowing for a more dynamic system to respond to the extreme weather. Examples of this kind of work include the recent protection of 40 acres of wetland in the watershed and in cumulative over 6,000 acres in Washtenaw County, the removal of Mill Pond Dam in Dexter, buffer ordinances passed in 4 watershed communities in the last 4 years, the installation of over 1300 rainbarrels and 2 dozen rain gardens, and much more.
Without funding from the USGS and local government partners to maintain these gages, it would be far more difficult to “read” the river through stream flows. Unfortunately, the gage in Milford was discontinued in the past year due to tight budgets. More, not fewer, gages are what we need on the river.
Please join us in building resilient communities and watershed. Visit our website at hrwc.org.
Recently, I went to Washtenaw County Circuit Court about a lake level for Portage and Base (aka Baseline) Lakes in Washtenaw and Livingston County. Under Michigan’s Lake Level Control Act, residents who live on the lake can petition a judge to set a legal lake level. Yes, Legal! The County Drain Commissioner (or now know as the Water Resources Commissioner) has to keep the lake at the court ordered level. These lake levels are controlled by dams and their operators.
Most lakes that are formed by a dam for recreational purposes have a winter and summer level set by a judge. Higher in the summer for docks and boat traffic and lower in the winter to protect docks and shorelines from ice and damage.
The Court case I attended was to establish a winter lake level for Portage and Base Lakes. Standard practice was to lower the lake level in the winter, but there wasn’t a court set winter level. The Livingston and Washtenaw County Water Resources Commissioners petitioned the court to set a winter level 15-18 inches below the summer level. Some residents wanted the lake to be lowered 30 inches and the MDNR was opposed to a winter lake lowering.
In terms of this petition, HRWC understands the balance of interests in setting lakes levels—fisheries, homeowners, recreational enthusiasts, ecologists, and more. We also know the impacts of changing lake levels on the Huron River and its lakes. While a river and its watershed is a changing and dynamic system, there are boundaries to how far those variations should go. Three feet is too much. While scientists argue for no lowering of the lake level in winter, this is not publically acceptable at this time. Given past practices and expectations, a 15 inch winter draw down is the best strategy.
Why is three feet too much? Although drawdowns can produce relatively weed free conditions for short periods of time, over the long-term, frequent drawdowns may result in less diverse plants and native species and more monocultures or invasive nuisance species. Drawdowns resulting in bare sediment favor those species that colonize the fastest. Not surprisingly, these tend to be non-native nuisance species such as Eurasion watermilfoiil and Curlyleaf Pondweed. Over time, the drawdown can promote the replacement of a diverse native plant assemblage by monocultures of invasive exotic species….nuisance species that then result in lakewide herbicide and pesticide applications.
I agree with the direction of the Michigan Department of Natural Resources to limit the range of seasonal lake level controls as we’ve seen the detrimental effects of dry spring rivers. A gradual draw down and increase should be best practice for dam operators with the goal of minimizing extreme flows and providing a base flow. In terms of future policy and changes to the lake level control act, we strongly support a better quantification of minimum river flows for aquatic habitat and fisheries.
Water levels on the Huron River in Ann Arbor (see graph) began fluctuating wildly late last Saturday (1/22), according to a stream gauge monitored by the US Geological Survey. At peak flow levels, water discharge reached near 700 cubic feet per second, a high water mark with conditions that make it difficult and dangerous to wade in the river. At the low water mark, less than 70 cubic feet per second of water went down the river, leaving the bottom of the river mostly dry. The changes happened within minutes, a most unnatural phenomenon.
These rapid and extreme fluctuations are catastrophic for the aquatic life downstream of the dam. Any fish that cannot make it to deeper water will die from exposure while the river goes dry, and many aquatic insects that still are active on the stream bed, can be scoured away as the river gushes. These events affect aquatic insects more in the winter than any other time of year because most mayflies, caddisflies and stoneflies are in there larval and egg stages clinging to rocks on the bottom. They can be flushed out very easily. During the summer, they are fully grown larva or adults able to swim to deeper water.
Erratic stream flows in this reach of the river are happening with unfortunate regularity, posing significant risk to aquatic life, human lives and property downstream, and adding considerable costs to maintaining the dam.
For more details, see the Ann Arbor.com article
With funding from River Network, I traveled around Michigan this summer talking with the river and conservation community about the state of the state’s dams. Our experience with dams on the Huron River is revealing what’s working with the dam program in Michigan, and what’s broken. After talking with our peers also working on dam removal or repair, it’s clear that there’s much to improve if we’re going to protect Michigan’s rivers and citizens from unsafe, unproductive dams.
As the DNRE restructures itself, it’s the perfect time to make the voice of the river and conservation community heard on this critical issue. I’m preparing a summary of the regional meetings that will include a set of recommendations from the river and conservation community for how Michigan can become a leader in river conservation through selective dam removal. The recommendations will be presented to DNRE management and staff.
Ninety-three percent of Michigan’s 2,600 dams will reach or exceed their design life within the next 10 years and only a handful of them have funds for repairs, so there’s much work to do and bold steps must be taken to limit the fiscal, environmental and public safety toll.
I’ll blog here with updates on this initiative.
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.