Dam removal can be an emotive issue for the hydro industry if it is felt that other viable alternatives exist. At times, however, it cannot be avoided if dams are ageing, unsafe or no longer serving their original purpose. As Bob Martini explains, local communities may also oppose decommissioning of their dam, and find it difficult to understand that it can be an appropriate course of action
Since Wisconsin became a US state in 1848, official records show at least 4680 dams have been authorised for construction. On the other hand, over the past 150 years nearly 1000 dams have washed out or have been intentionally removed.
A recent analysis by Trout Unlimited lists Wisconsin as the state with the most dam removals in the US over the past two decades. At least 58 dams have been removed since the early 1980s, according to the report. Current estimates list over 3700 dams still in existence today, and approximately 300 of these are in need of significant repair.
The Wisconsin Department of Natural Resources manages natural resources in trust for the owners; the citizens of the state. This responsibility includes protection of aquatic and terrestrial habitat, navigation, aesthetics, water quality and public safety. When the Department is reviewing an owner’s decision to remove a dam, it takes action only after ample opportunity has been given to anyone who might be willing to take ownership and repair the dam. Removal is preceded by an extensive environmental cons-equences analysis and exhaustive public involvement. In this sense, dam removals in Wisconsin are selective, not systematic.
To remove or not to remove
Of the 3700 dams known to exist in Wisconsin, approximately 110 are licensed by the Federal Energy Regulatory Commission (FERC). Most FERC dams are unlikely to be removed, although at least three are scheduled to be removed as part of a recent settlement agreement. The remaining 3590 dams are under the jurisdiction of the Wisconsin Department of Natural Resources. Until about 1995, the primary concern of the Department was dam safety. Since then, a more holistic approach has been taken involving concerns for fish and wildlife habitat, recreation, aesthetics, navigation, water quality and other important Public Trust issues. New information on the importance of biodiversity, ecosystem-based management, and a new rivers management programme have compelled an expanded context for dam related decision making. A team approach involving experts from multiple disciplines including fisheries, wildlife, endangered resources, water quality, legal counsel, engineering, public relations, and health, is often utilised to evaluate a wide array of dam safety options. Even in this broadened context, however, protection of public safety and property is the ‘trump card’ of the programme.
State law requires a dam safety inspection at least once every ten years for all large dams. Because of a shortage of dam safety engineers, this frequency has slipped to about once every 17 years in reality. In contrast, FERC-licensed dams are required to be inspected annually with more thorough analysis every five years.
Due to infrequent inspections, a dam’s natural enemies (water, ice, gravity and economics) often cause damage that goes unreported and unaddressed for over a decade. When a Department dam safety engineer finally visits there are often multiple deficiencies to correct. Common problems include downstream floodplain development; inadequate spillway capacity for flood protection levels required in state statutes; steel and concrete damage; inoperable gates; erosion; woody vegetation on dikes; seepage; excessive settling; and operation problems. In our experience some dam owners can often neglect routine maintenance and fail to recognise that dams have a limited design life.
Many dam inspection reports list a dozen or more deficiencies which the owner is often ordered to correct. Compliance schedules as long as ten years may be granted but essential repairs may be required immediately for major safety concerns. Since most dams under state authority do not produce hydro power (and consequently do not create a revenue stream) the owner is faced with a remove or repair conundrum. Since repairs often involve major reconstruction of the structure, the owner can easily face unanticipated costs ranging from hundreds of thousands to millions of dollars. When the owner concludes the cost is unjustifiable or unobtainable, the problem often becomes a major community issue.
Communities often have difficulty dealing with dam repair or removal decisions for several of the following reasons:
1. Many people have fond and direct memories associated with the impoundment formed by the dam. In most cases, no one in the community remembers the pre-dam condition of the river. Wisconsin has been a national leader in its attempts to build public support for the value of lakes and the need to preserve shorelines. This successful programme, coupled with the ancient human affinity for water views and benefits, creates a strong emotional bond between people and their local waterbody. When a dam is proposed for removal, the public individually and collectively pass through the classic stages of grief; shock, denial, anger, depression, and eventually, acceptance or coping. These stages of grief make it difficult to communicate the complex engineering, dam safety, environmental and economic issues necessary to resolve the repair or remove question. Some people never get past the early stages of grief.
2. Often the average citizen is unfamiliar with basic engineering concepts, probability (eg regional flood forecasting), economic principles and environmental analysis techniques which can inhibit rational communication and collective decision making. Several myths of dam removal invariably surface: the idea that the dam will no longer provide flood control, in spite of the fact the structure never had any flood control capacity to begin with (the dam may actually make the flood situation worse due to the need for a dam break analysis); the mistaken belief that the river will dry up if the dam is removed because ‘the river’s water comes from the pond’ formed by the dam; and the misconception that the mud flats resulting from dam removal will remain unsightly for years.
3. Most people do not understand or accept the need for basic dam safety features required by law, eg spillway capacity needed to withstand a regional flood, structural monitoring, concrete repair and maintenance. When faced with an unsafe dam they often cannot believe how expensive dam repairs can become and occasionally accuse the Department of inflating repair cost estimates to favour dam removal. In most cases, high cost repairs are not offset by revenue; therefore, repair funds are sought from various units of government. A recent University of Wisconsin study found that in Wisconsin cases over the last 20 years, the dam repair option was often four to five times as expensive as the dam removal option.
4. Interests with riparian ownership or potential to profit from the existence of a lake may exaggerate perceived problems associated with dam removal to create opposition. The following issues are examples of misconceptions or problems recently used to argue against dam removals in Wisconsin:
•Stormwater management from city streets will be difficult and expensive.
•Undesirable vegetation will take over the dewatered bed.
•Blastomycosis (a fungal lung disease) cases will increase in the area.
•The cost of removal is higher than the repair cost.
•Fish will die.
•Flooding will increase.
•The river will dry up.
•Social problems (beer parties, crime, litter) will occur on the dewatered bed.
•The area will be unsightly for years.
•Wells will dry up.
•Downstream parks will be flooded and covered with sediment if the dam is removed.
•Eagles will relocate, beavers will dam the river, migrating birds will not have a place to rest.
•Property values will decline; the tax base for schools will erode.
•Endangered species and other wildlife will be adversely affected.
In the face of the above perceived consequences, why even consider dam removal as a viable option? For each issue listed above, an environmental analysis conducted by the Department showed that the perceived problems would not occur or could be mitigated if proper management practices were included in the dam removal plan.
On the other hand, several dam removal environmental analyses conducted recently by the Department at locations all over Wisconsin have identified the following advantages for the selective removal of unsafe dams:
•Cost to taxpayers is lower than reconstruction and long term care.
•Dam break flood hazards are eliminated thus reducing flood insurance costs and damage potential.
•Fish movement is allowed for the first time in many decades (in most cases).
•Overlap fisheries are developed; cold water, cool water and warm water fish communities occur at different times in the same river reach.
•Aquatic biodiversity increases above and below the dam.
•Water quality improves (temperatures are lower, dissolved oxygen is higher).
•In some cases, formerly riparian property values can increase depending on the type of recovery plan developed for the land created by draining the pond.
•Public access and recreational uses increase if the exposed lakebed is developed into a park or is donated to local units of government.
•The ‘river continuum concept’ is restored allowing the river to perform its normal functions including sediment movement, fish migration, carbon movement, habitat maintenance, wetland enhancement and flood attenuation.
•Fish and other aquatic species are able to move to seek their various seasonal, daily, or life stage habitat needs. Fish communities are more stable as a result of habitat accessibility.
Not the preferred option
In spite of the above advantages of dam removal, there are cases where removal is not the preferred option. If anyone comes forward with the financial, engineering, and long term ownership capabilities required for dam ownership, under Wisconsin law that person is entitled to apply for a permit to own and maintain the dam. In some cases, dam removal will alter the hydraulic properties of a river enough to cut new channels which could resuspend entombed toxic materials in currently vegetated alluvial sediments. Some public safety, water quality, or wildlife habitat situations might favour dam repair if the dam is publicly owned and funds are available to upgrade the structure. If the value of the pond created by the dam is truly as high as dam removal opponents claim, then it follows that the political process will authorise the necessary public repair funds which were not available from private sources, including the owner.
The mechanism for these difficult decisions is the public involvement process. Most dam repair or remove questions are not resolved until several public meetings, hearings and information sessions are held. Press coverage is usually extensive. Involvement of local and state elected officials is a feature of virtually every case. Multiple state and local agencies are involved. Up to a dozen legal challenges per dam removal have occurred.
Wisconsin has been involved in many dam removal decisions over the past few decades. We have learnt some of the following lessons from the Wisconsin dam decommissioning experience, which may also be applicable to other areas:
•Do not underestimate the depth of feeling people have about their local waterbody. Extensive public involvement is essential to the local decision making process but even the best public involvement may not overcome all participants’ anger, frustration, and resentment over dam removal. (Bomb threats and personal intimidation have occurred in some cases.)
•Each case has site specific issues, problems and characteristics. Dam removal policies need to be flexible, data driven and selective, not general in scope.
•Most dam removal cases will consume all the staff time available and tasks will still go undone. The actual removal process requires on-site, daily oversight by engineering and biological professionals to address unforeseen problems.
•An adequate dam safety inspection and data management system is essential to choose those sites with high habitat benefit potential from among the numerous dams that do not meet safety standards.
•An interdisciplinary basinwide approach is necessary to choose and plan dam removal candidates which are unsafe, unlikely to be rebuilt, and will result in the most Public Trust benefits.
•Now that gross water pollution problems have largely been addressed in Wisconsin (over 90% of point sources meet or exceed Clean Water Act standards), many aquatic biologists believe there is nothing river managers can do to improve aquatic habitat more effectively than selective removal of unsafe dams.
Although Wisconsin has had extensive experience with dam removal issues, the process is continually evolving. For example, we are currently developing detailed rules and guidelines for fish passage at dams even though authority to order fish passage has been a feature of Wisconsin law since the 1830s when we were still a territory.
We will continue to develop and refine a process that holistically weighs all the Public Trust issues in consultation with the people when deciding the fate of dams in Wisconsin.
|Prairie Dells dam|
| Built: 1880s. Upgraded in 1904.
Purpose: originally authorised as a log drive dam, this site was upgraded to an 18m hydroelectric dam. But the engineer made a decimal error, overestimating the amount of water available, so the turbines were never installed.
Reason for removal: dam safety problems (deteriorating concrete, spillway capacity).
Location and description: this dam impounded the Prairie river, an important trout stream with a mean annual flow of about 180cfs in north central Wisconsin. One of four dams on the Prairie river, this dam removal restored a very high quality trout fishery and a high quality white water boating reach.
Date of removal: breached 1983; removed 1992.
Approximate cost of removal: US$200,000
Approximate cost of repair: in excess of US$1M.
Restoration activities: the former pond was left in its wild state and revegetated naturally with a small amount of rye grass planted for temporary stabilisation of sediment. A sediment trap downstream removed sand and sediment over a five-year period after breaching of the dam. Mayflies, caddis, stoneflies, trout and whitewater paddlers recolonised the stream reach within one year of dam removal. Brook trout reproduction increased 30-fold after the scars of dam removal healed.
| Built: 1888. Upgraded to a modern structure in 1904.
Purpose: logging dam and hydroelectric power production.
Reason for removal: inadequate spillway capacity, concrete and gate deterioration, discontinuation of hydro production. In 1996 flooding damage around the impoundment occurred due to improper operation.
Location: downstream-most dam of four on the Prairie river – a significant Midwest trout stream and source of the state record brook trout. At the time of removal it was the last remaining Prairie river dam, opening up a system of 362km of river and tributaries to fish passage for the first time in over 110 years.
Date of removal: September/October 1999.
Approximate cost of removal: US$200,000
Approximate cost of repair: US$1.5-2M.
Restoration activities: 1088kg of rye grass was planted on the 48ha former lake bed. Reclaimed land is to be donated to local units of government for a park which is currently being designed. Wisconsin DNR is planning trout habitat improvement and streambank stabilisation work.