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Solution

A Modern Approach to Water Management

The new approach uses state-of-the-art analytical techniques and improved data to address the challenges of today and prepare for the challenges of tomorrow. It includes a modern regulation plan and an adaptive management strategy based on a new generation of data and tools. The new approach will also include new policies, such as an Order of Approval and Deviations Policy, which are currently being drafted for public review.

Advances in understanding form the basis for the new approach, which seeks to restore greater balance to the region's regulation of water levels and flows. Studies show that modest changes in water level variability on Lake Ontario and the upper St. Lawrence River would help restore the region's wetlands and contribute significantly to a healthier lake and river. At the same time, other basin interests would retain most of the benefits they now receive in the form of reduced extreme high and low water levels. Expected results and any unforeseen consequences would be systematically monitored and evaluated under the adaptive management strategy.

We know we must prepare for conditions that are wetter and drier than those the current approach was based on. Plan Bv7, the IJC's proposed regulation plan, is designed to perform under more realistic water supplies, including those experienced since the 1950s and statistically-generated water supply scenarios that are more extreme, but still considered to be likely under the current climate regime. The proposed plan also incorporates practical experience gained from 50 years of operation under many different water supply and ice conditions.

The International Lake Ontario-St. Lawrence River Study generated a wealth of new knowledge on how water level regulation affects basin interests, including environmental, coastal property and recreational boating. After evaluating over 400 environmental performance indicators, the study analyzed 32 that were sensitive to water levels and representative of ecosystem health. Effects to property were estimated from a parcel database of buildings and shore protection structures, building elevations, 40 years of hourly wave height and direction data, and historical erosion rates. Effects to recreational boating were estimated from an inventory of all marinas, yacht clubs and launch ramps, as well as surveys of boaters and charter and tour boat operators. Substantial work after the study to complete the parcel database in Canada and on Lake St. Lawrence, and refine the models of environmental performance and flow management during ice formation has strengthened our understanding of how water levels regulation affects basin interests.

A New Regulation Plan

Compared to the current plan, the proposed plan would raise the monthly average Lake Ontario water level by 6 centimeters (2.4 inches) in April, 3 centimeters (1.2 inches) in June, and 5 cm (2 inches) in October using water supplies of the 20th Century. Unregulated water levels would be significantly higher than the levels under either plan. All of the graphs in the animation are available in the library section of the website.

The proposed regulation plan will specify the operational rules for managing Lake Ontario outflows at the Moses-Saunders Dam. It is called Plan Bv7 because it is version seven of Plan B that was developed during the International Lake Ontario-St. Lawrence River Study. Plan Bv7 was developed and analyzed by technical experts from governmental agencies in Canada and the United States who participated in the study.

Plan Bv7 attempts to more closely follow natural patterns of water levels and flows than the current regulation plan. Compared to the current plan, it allows more variability in water levels from year to year on Lake Ontario and the upper St. Lawrence River in order to improve the health and diversity of coastal wetlands. Compared to the natural state, it substantially reduces the frequency and duration of extreme water levels throughout the Lake Ontario-St. Lawrence River system to nearly the same degree as the current plan.

Using the water supplies experienced during the 20th Century, Plan Bv7 would raise the maximum level of Lake Ontario under the most extreme circumstances by 6 centimeters (2.4 inches) from 75.68 meters to 75.74 meters (from 248.3 feet to 248.5 feet) compared to the current plan. It would lower the minimum level by 21 centimeters (8 inches) from 73.78 meters to 73.57 meters (from 242.1 feet to 241.4 feet) compared the current plan. The table below shows the standard plan comparison with the range of levels that would be experienced on Lake Ontario 90 percent of the time using the same water supplies.

Plan Comparison for Lake Ontario*

Plan 1958DD Plan Bv7 Difference
High water supplies 75.20 m 246.7 ft 75.34 m 247.2 ft +14 cm +5.5 in
Average water supplies 74.74 m 245.2 ft 74.80 m 245.4 ft + 6 cm +2.4 in
Low water supplies 74.30 m 243.8 ft 74.26 m 243.6 ft -4 cm -1.6 in

*Comparison uses water supplies from the 1900-2000. During this period, the high supply scenario is exceeded 5% of the time, the average supply scenario is exceeded 50% of the time and the low supply scenario is exceeded 95% of the time.

Using the water supplies of the 20th Century, Plan Bv7 does not change the maximum or average water levels of the Lac St. Louis portion of the St. Lawrence River, but would decrease the minimum level under the most extreme circumstances by 13 centimeters (5 inches) compared to the current plan. The table below shows the standard plan comparison with the range of levels that would be experienced on Lac St. Louis 90 percent of the time using the same water supplies.

Plan Comparison for Lac St. Louis*

Plan 1958DD Plan Bv7 Difference
High water supplies 21.97 m 72.0 ft 21.97 m 72.0 ft 0 0
Average water supplies 21.17 m 69.5 ft 21.17 m 69.5 ft 0 0
Low water supplies 20.61 m 67.6 ft 20.60 m 67.6 ft -1 cm -0.4 in

*Comparison uses water supplies from the 1900-2000. During this period, the high supply scenario is exceeded 5% of the time, the average supply scenario is exceeded 50% of the time and the low supply scenario is exceeded 95% of the time.

A comprehensive set of graphs and tables of water levels at various locations in the system is provided in the library section of the website.

A New Order of Approval

The new Order of Approval will provide the policy framework for the new approach. It will establish the criteria for regulating the outflow from Lake Ontario through the Moses-Saunders Dam. In the current Order, for example, criteria (a) through (k) specify maximum outflows from Lake Ontario, minimum levels at Montreal Harbour and a target range of levels on Lake Ontario that should be met when water supplies are not more extreme than those experienced prior to 1954. The Order also creates a Board to oversee the Order's implementation.

The Order ensures compliance with the Boundary Waters Treaty. In particular, water uses should not conflict with those given a higher priority in Article VIII of the treaty. Under Article VIII, IJC shall also require that suitable and adequate provision be made for all interests that may be injured by changes in natural water levels resulting from the construction or operation of the dam. The IJC will seek the concurrence of the federal governments of Canada and the United States before implementing a new Order.

Deviations Policy

The current Order of Approval is based on the 1860-1954 historic record of water supplies. When supplies are outside of this historic range, flows through the dam are set in an ad hoc manner rather than by the regulation plan. During times when supplies are above the historic range, flow decisions are made to provide all possible relief to coastal communities and property owners upstream and downstream of the dam. When supplies are below the historic range, flows are set to provide relief to navigation and hydropower interests. The new Order will also provide for deviations during extreme water supply conditions, but such deviations would be required less frequently because the new regulation plan would function over a wider range of conditions than the current one.

In addition, the new Order will continue to provide authority for deviations from the regulation plan to meet short-term needs. These include ice management needs; emergency situations such as failure of a lock, flooding of the hydropower plant or large-scale black out; assistance to commercial vessels; and flow changes to assist with recreational boat haul out at the end of the season. Flows will be adjusted as soon as conditions permit to offset the effect of short-term deviations on Lake Ontario water levels. Finally, flows through the dam will also be adjusted when conditions, such as springtime Ottawa River flows and ice conditions, change from forecasted conditions. Guidelines are being developed for deviations and other flow adjustments.

  • Background

Learn more about the history of regulating water levels and flows on Lake Ontario

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