High water levels generally benefit municipal water users, shipping, hydroelectric generation, and recreational boaters. High water levels negatively impact riparian owners by overtopping fixed docks or flooding buildings close to the water’s edge. In addition, shoreline erosion rates are often greater with higher water levels, and shoreline protection structures can be damaged with extreme high water levels. Wetlands extend further inland with higher water and are inundated to greater depths, which is beneficial from time-to-time. Periodic high water levels are necessary to sustain wetlandproductivity and health.
Low water levels negatively impact municipal users as the water intakes may be above the water surface or affected by warmer and poorer quality water. Low water levels result in less water available for dilution of municipal waste water, or increased cost for treatment. Shipping and boating interests are adversely affected by low water as channels are shallower. Ships may need to lighten their loads to decrease the draft and recreational boaters may find that docks or launches do not extend sufficiently far. Hydroelectric generation is affected by lower available head or lower flows.
Low water levels benefit riparian owners whose docks may be short and low or who have buildings too close to the water’s edge. Erosion rates generally decrease with lower water levels.
Periodic low summer water levels can also result in positive environmental benefits. Low water levels expose more beach and mudflats. Additionally, wetland vegetation may extend further into the lake and river. Wetland dewatering encourages dormant aquatic seed bed germination, benefiting wetland plant species and biodiversity.
Although Lake Superior is to be regulated above 182.76 m (599.61 ft) and below 183.86 m (603.22 ft) (both monthly means), and the regulation plan also has provisions to protect downstream interests from extreme highs and lows, there are no specific critical low or high water levels at which it can be said that "adverse impacts" occur in the system. The level of harm experienced by a user of the system greatly depends on the location and the usage and sometimes the time of the year. The International Joint Commission (IJC) and the Board are aware that various sectors in the system may be impacted as levels in Lake Superior, the St. Marys River, and Lake Michigan-Huron vary, even within their historical ranges. The Board encourages users to be aware of the possible ranges of water levels and to be prepared to adapt, to the degree possible, to adverse conditions.
Shoreline communities can help the Board by communicating your situation and concerns (Contact Us). More importantly, shoreline communities can help themselves by becoming better informed about coastal hazards and taking action to reduce their risks to such hazards, particularly through incorporating risk reduction measures into shoreline revitalization efforts and long-term planning of coastal zone uses.
As water levels affect many interests, perhaps one of yours, the Board has many ways to communicate water levels in the system. The Data page of the Board website indicates recent and forecasted water levels. This page lists news releases.
The Board encourages everyone to be aware of water levels and to be prepared to live within the range of levels possible in your area. The range of monthly mean levels specified in the Orders of Approval for Lake Superior is between 182.76 m (599.61 ft) and 183.86 m (603.22 ft) or a range of 1.10 m (3.6 ft). Levels downstream tend to vary more widely.
High water levels can threaten domestic water supplies and sanitary uses. These consist of flooding and backup of sanitary sewer lines, flooding and contamination of freshwater storage wells, and flooding of freshwater intake pumping facilities under very high levels or during storm events.
Very low water level conditions may affect shore wells and municipal and industrial water intakes. Such impacts can be avoided through proper design of such facilities, with anticipation of the entire range of levels and flows prescribed by the Orders of Approval.
The construction of the Soo Locks and the Seaway and power project opened the Great Lakes to ocean-going and inter-lake navigation. In general, high outflows and water levels in the lower St. Marys River do not pose a problem for commercial navigation. By contrast, very low outflows can result in extremely low levels in downstream areas of the River, limiting the ability of vessels to transit the channels and/or approach docks. Under certain conditions, shippers may have to lighten their vessels, forcing them to either leave cargo behind or increase the number of transits necessary. Otherwise, shippers may be forced to wait for levels to rise before they can transit the River safely.
Yes. Though storms and adverse weather conditions can force vessels to seek shelter and possibly force them to stop altogether, normally lake levels do not impact navigation interests significantly while vessels are in transit out in the open lakes. However, depending on where a vessel is transiting to or from, when water levels are low, vessels may need to reduce the amount of cargo they carry each trip, or they may need to avoid certain harbours or berths altogether. In the St. Marys River, navigation channels upstream of the locks are sufficiently deep to ensure that vessels can reach the locks under most weather conditions. Typically depth restrictions downstream prove critical with respect to how much cargo a vessel can load to safely transit the length of the entire River.
Generally and up to a certain point, yes. For hydropower, more electricity can usually be generated when there is a greater volume of water passing through the turbines. However, the higher flows also result in the lowering of upstream levels and increasing of downstream levels, and this decreases the net head on the hydropower stations, thereby decreasing the amount of electricity generated for a given volume of water. Finally, extremely high outflows may exceed the capacity of the hydroelectric facilities, resulting in water being diverted around the generating equipment and being lost in terms of power generation, and in lieu, spilled down the Rapids through the Compensating Works.
5.4.2 When the Board increases outflows from Lake Superior is the water spilt or is it still used to generate electricity?
The generating capacity of the three hydropower plants is around 2,280 m3/s when all units are available under typical conditions. Since the average total Lake Superior outflow is approximately 2,110 m3/s, the water is typically not spilt when outflow is increased. However, a minimum flow of 1/2; gate open equivalent must be passed to the main portion of the St. Marys Rapids at all times, and Gate #1 remains continually set to pass a flow of about 15 m3/s. This water, though technically "spilt" (as it does not pass through the hydropower turbines) is crucial for keeping world-class fishery habitatviable. However, when the power entities have maintenance and/or the allocated flows exceed the capacity of their plants (e.g. such as when Lake Superior is high relative to Lake Michigan-Huron), excess water must be spilt by opening additional gates at the Compensating Works in order to best maintain the balance in lake levels upstream and downstream. Historically, this has occurred less than 9% of the time. It is worth noting that the vast majority of the time, there is relatively little water being passed through the gates of the Compensating Works and (although the cascading water in the Rapids certainly provides an awesome visual spectacle at times) most of the water passing down the River is passing through the turbines of the power plants and exiting downstream.
The Board allocates water to the various users, such as hydropower, on a monthly basis. The power entities, in the best interest of their customers, make every effort to use this water as efficiently and effectively as possible to produce electricity. It makes sense to try and match power production with the demand for electricity to the extent possible. Therefore, the hydropower plants will "peak", or pass more water during the higher demand times during a given day, and less during the lower demand periods, such as at night. Likewise, they may "pond", whereby they will pass less water on the weekends and holidays, when demand is lower, and more on weekdays, when electrical demand is higher. In so doing, this can cause fluctuations in water levels, particularly in the St. Marys River downstream of the hydropower plants. The Board has determined that water levels in the Soo Harbor area can vary by approximately 16 cm (6.3 inches) for every 1,000 m3/s variation in the flow. It is worth noting that wind effects and other secondary factors can result in comparable fluctuations in River levels, and that the effect of peaking and ponding operations dissipate very quickly as one travels downriver, such that downstream of Soo Harbor, the impact is minimal.
In 2015, the IJC issued a Directive to the Board regarding peaking and ponding. In 2002, the Board established a guideline by which it may restrict peaking and ponding operations by the hydropower entities under certain low-water conditions to ensure adequate water levels for commercial vessels to transit the lower River safely.
Plan 2012 was developed taking into account many environmental and economic indicators and various stakeholders. Significant environmental enhancements and benefits are expected to be achieved over the long-term, particularly in the St. Marys River, where the environmental impacts of regulation are most prominent.
No, the International Upper Great Lakes Study concluded that regulation has not had a negative impact on the wetlands and wetland-supported habitats of Lake Superior or Lake Michigan-Huron, including the Georgian Bay region. While each wetland is unique, they tend to benefit from natural, periodic water level fluctuations, but area also prone to damage during extended periods of high or low lake levels. However, such water level fluctuations are driven more by the water supplies and weather conditions experienced on the lakes, rather than regulation of Lake Superior outflows.
5.5.3 Has regulation impacted the St. Marys River environment and what are the St. Marys Rapids Fishery Remedial Works?
The most significant impacts of Lake Superior outflow regulation on the St. Marys River are in the vicinity of the various control structures and in the St. Marys Rapids area. The St. Marys Rapids drop over 6.1 m (20 ft) in a 1.2 km (0.8 mile) reach, resulting in fast-flowing water dominated by cobbles, boulders, and bedrock. Such features and fast flows are lacking throughout the remainder of the 112-km (70-mile) long river, making the St. Marys Rapids a key fishery for native fish. Although this habitat was historically significant, construction of the Compensating Works and hydropower facilities diverted over 90% of the Lake Superior outflow and dewatered over 25 hectares (62 acres) of the Rapids.
Recognizing this, the IJC, through its Orders of Approval, has specified a number of conditions and criteria that must be met in the regulation of Lake Superior in order to protect the St. Marys Rapids. In 1981, a concrete wall known as the Fishery Remedial Works Dike was constructed downstream of Gate #1 of the Compensating Works and immediately adjacent to Whitefish Island. This is an area of enhanced fisheries habitat, completed in 1985, located along the south shore of Whitefish Island and to the north of the Fishery Remedial Works Dike, and the IJC’s Orders of Approval require that Gate #1 remains partially open at all times with an equivalent of approximately 15 m3/s of water passing through it to continuously achieve a minimum water level in this area equal to that provided by opening four gates in the Compensating Works prior to construction of the dike.
Additionally, the Orders require that the water level in the main St. Marys Rapids, to the south of the dike, be maintained at least equal to that which would have occurred with one-half gate open in the Compensating Works before the dike was constructed. A minimum half-gate equivalent setting is typically maintained by partially opening four gates to more evenly distribute the flow across the width of the main rapids. Recently, another condition was added to the 2014 Supplementary Orders of Approval which requires that the rate at which the Compensating Works gates are opened and closed be such as to minimize the risk of fish and other aquatic animals from being flushed or stranded in the St. Marys Rapids.
Finally, Lake Superior Regulation Plan 2012 itself was developed to provide more natural flow conditions in the St. Marys River in comparison to the previous regulation plan, and Plan 2012 also contains a specific provision to protect critical sturgeon spawning habitat in the St. Marys Rapids during periods of low flows.
Additional information that may be of interest to riparian and shoreline property owners can be found on the Reports page, including a Buyers Guide to Shoreline Property, Living with the Lakes – Understanding and Adapting to Great Lakes Water Level Changes, and Living on the Coast – Protecting Investments in Shore Property.
The major factors affecting long-term erosion rates include shoreline materials and structure, long-term patterns of sediment transport along the shore, and water levels. These factors have caused erosion since the last ice age and will continue to cause erosion in the future.
Strong winds are responsible for significant erosion over short time periods. When water levels are high, wind-driven waves can trigger significant short-term erosion events that would otherwise occur later or more gradually. They may also direct wave energy against existing erosion protection structures, sometimes resulting in damage. With extremely high water levels, waves may also directly impact and damage dwellings and other structures near the shoreline. High water levels also result in localized flooding of roads and other public facilities and may result in damage to private property as well as public water and sewage facilities. Studies have shown that damages to shoreline property and shoreline protection structures increase with increasing mean water levels. While long-term recession rates appear to be independent of water level fluctuations for some Great Lakes shoreline areas, water level fluctuations do play a role in determining long-term recession in others. The water level fluctuations may also influence beneficial shoreline sand deposition and sand dune replenishment.
Yes. Some spots around a lake or along a river are naturally deep and may be well protected from wave and current action, while other spots lie in shallow-sloped bays open to the lake and high wind-driven waves. Fast-flowing bends in a river are more susceptible to erosion. Other spots may be inaccessible under certain water level conditions that may or may not be particularly extreme. This is why the Board encourages riparians to be aware of all possible water level or outflow conditions likely at your specific location, and to do your best to adapt to the full possible range that you might experience. The valued adage "Buyer Beware" certainly applies to waterfront property.
5.6.3 What have been the benefits to riparian property owners as a result of Lake Superior regulation?
Regulation of Lake Superior outflows has reduced the frequency and magnitude of extremely high water levels and flooding, both upstream and downstream. Most notably, regulation of Lake Superior outflows has greatly reduced the incidence of ice jams in the St. Marys River, thus reducing the flooding and shoreline damage often associated with these events.
Yes. The design and siting of water intakes and recreational boating facilities should take into account the entire range of water levels to be expected. In general, no federal, state, or provincial regulations have been implemented to assure that adequate designs are used. For recreational boating facilities, adequate investment in dredging, including securing necessary permits, is also effective in dealing with low water levels that should be expected to occur on occasion as a result of low water supplies.
5.6.5 Are there ways to address flooding and erosion problems other than through regulating water levels?
While shoreline protection may be effective in some instances, the best way to address flooding and erosion problems is through effective shoreline management. This is primarily a local, state, or provincial government function. State regulations pursuant to State Coastal Erosion Hazard Acts implement several actions to reduce flooding and erosion losses along shorelines. The Province of Ontario addresses flooding and erosion problems with flood plain management measures that provide easements and restricted building zones along the shore.
State and provincial actions that have been found to be effective include:
- For new structures, flood and erosion setbacks that consider long-term recession rates,
- Prohibitions on removing or damaging natural shoreline protective features such as bluffs and dunes,
- Prohibitions of any construction or structures within flood hazard areas,
- Relocation of structures at risk,
- Real estate disclosure requirements,
- Acquisition of high-risk undeveloped land,
- Limiting construction in flood plains, and
- Purchase of flood easements within flood plains.
5.6.6 What can I, as a landowner, do to protect myself from high water damages to my property? What can the Board do to help me?
As a landowner, it is important to build with the knowledge that water levels fluctuate, and to know the extremes possible at your location. The Board urges everyone to be prepared to live within the full range of levels that could occur. Though the Board strives to maintain the range of monthly mean levels of Lake Superior below the upper limit of 183.86 m (603.22 ft) and above the lower limit of 182.76 m (599.61 ft) specified in the Orders of Approval, levels outside of this range could occur in the future under extreme hydrologic conditions. Know the extent to which high water and winds act and build accordingly. Structures such as breakwaters and heavy stone may protect against strong wind action if built correctly. Residences should be built with sufficient setback to avoid flood and erosion damages into the future. The Board announces flows and water levels monthly online and through the media.
5.7.1 Other than water level regulation, are there any actions that could benefit recreational boaters?
Recreational boaters have problems navigating at different points on the lakes and on the river, even when levels and flows are within the ranges in the Order. For example, a private dock or a marina built during high water levels may not be fully usable when water levels fall. Therefore, one action to alleviate this is to site, design, and maintain new and existing recreational boating facilities, taking into account the full range of water levels and flows, at minimum as defined in the Orders of Approval for Lake Superior and as have occurred in the past along the St. Marys River and downstream on Lake Michigan-Huron. This may necessitate the use of longer launch ramps, floating (rather than fixed) docking systems, and the financial commitment and permits to perform periodic maintenance dredging as needed to accommodate the planned use. Also, it must be recognized that some areas are shallow and cannot accommodate dockage for large recreational vessels. In addition, boaters should pay particular attention to navigation charts during low water periods, even in waters with which they may be familiar.
Many areas of the upper Great Lakes, and in particular, along the St. Marys River, are considered world-class fishing spots. An especially important and world-renowned location is the St. Marys Rapids, just downstream of the Compensating Works, in the St. Marys River between Sault Ste. Marie, Ontario and Sault Ste. Marie, Michigan. Fluctuating water levels and outflows can make it difficult or impossible for anglers to access their favourite fishing holes, and regulatory operations can frustrate seasoned and novice anglers alike as they try to access these locations during high-water periods. The Board encourages all anglers to check outflow and water level conditions while planning their fishing trips to avoid potential disappointment, and reminds anglers that it is far more important to avoid a dangerous situation than to risk injury or death for a chance at that prize catch.