Proposal for Lake Ontario and St. Lawrence River Regulation


The proposal for Lake Ontario-St. Lawrence River regulation includes the following elements:

  1. A  regulation plan
  2. An Order of Approval
  3. An International Lake Ontario-St. Lawrence River Board
  4. A policy for deviating from regulation plan flows
  5. An adaptive management strategy

 1. Lake Ontario-St. Lawrence River Plan 2014

Lake Ontario-St. Lawrence River Plan 2014 (Plan 2014) enhances the environment on Lake Ontario and upper St. Lawrence River while retaining the protection and benefits downstream in the lower river equivalent to what they are now.  The Commission finds this balance to be reasonable since the environmental benefits that accrue under the new plan are focused on Lake Ontario and the upper St. Lawrence River. The Plan is designed to respond to concerns about Bv7 from coastal and riparian homeowners both on Lake Ontario and the St. Lawrence River, the St. Lawrence Seaway and the Port of Montreal. Plan 2014 includes a refinement of Regulation Plan Bv7 and provision for deviations to be made when Lake Ontario water levels are outside the range shown in Figure 1. The new Board will have the authority to deviate from the regulation plan releases when Lake Ontario reaches trigger levels, with different high and low triggers for each quarter-month that reflect the seasonal nature of water supplies and lake levels. When Lake Ontario is within those trigger levels, releases will be made according to Plan 2014, with the same sort of adjustments for river flows that are used now to manage ice, the Ottawa River spring flood and shipping emergencies. 

Plan 2014 performs about as well as Plan B+ for the environment.  And it performs better than B+ and much better than Bv7 alone for south shore erosion protection structures, although not as well as Plan 1958D with deviations.  Compared to plan B+, Plan 2014 provides slightly deeper water for the Port of Montreal, slightly increased flood protection for those who live along the lower St. Lawrence River and slightly improved depth conditions for the Seaway when Lake Ontario levels are low.  The estimated benefit to the environment from Plan 2014, including the expected deviations, is close to the benefit provided by B+, and the incremental increase in risk to shoreline structures is smaller.

2.  Order of Approval 

The Commission proposes revisions to the existing Order of Approval consistent with the Boundary Waters Treaty.    The criteria in the new Order of Approval have been formulated to maintain protections provided in the 1952 and 1956 Orders to the maximum extent, but take into account the wider range of water supplies experienced since 1960, the potential impacts of climate change, and add consideration for the environment and recreational boating, two interests that were not taken into account in the Orders from the 1950s.   The criteria of the proposed new Order provides equivalent protections and benefits downstream in the lower river to those that now exist.

3.  International Lake Ontario – St. Lawrence River Board 

The proposed new Order of Approval replaces the current Board of Control with the International Lake Ontario – St. Lawrence River Board.  The new Board normally will have a minimum of 10 members and will oversee the day to day regulation of Lake Ontario outflows much like the current Board does, but it will also have additional duties related to adaptive management, communications and public involvement.  The Commission will appoint the Board members, an equal number from each country, with at least one each from the two Federal and three state and provincial governments.  The five jurisdictions may nominate candidates for the Board. 

4.  Policy for Deviating from Regulation Plan Flows

The proposed new Order of Approval authorizes the Board to deviate from the flows specified by regulation Plan Bv7.  There will be three kinds of flow deviations: minor deviations that do not significantly affect Lake Ontario levels; major deviations that are meant to moderate water levels on the lake and river to avoid extreme high and low water level impacts; and emergency deviations, made when there is a risk to life or physical damage to the control structures.

Minor deviations are short-term changes in flow that typically respond to immediate needs including hydropower unit maintenance, to help commercial vessels confront lower than forecasted River water levels, to haul boats out of Lake St. Lawrence or Lake St. Louis at the end of the boating season, and to deal with unexpected ice problems on the river downstream of Montreal.  Minor deviations affect upper and lower St. Lawrence River levels and flows but do not significantly affect Lake Ontario levels.  These deviations will continue to be made as they have been under the current regulation regime.

Major deviations are more significant changes from the regulation plan specified flow that moderate the most extreme levels on the lake and river.  When Lake Ontario levels hit the high trigger levels shown in Figure 1, the new Order and the Directive on Deviations instructs the new Board to make releases so as “to provide all possible relief to the riparian owners upstream and downstream”.  When the low trigger levels in Figure 1 are reached on Lake Ontario, the Order and the Directive on Deviations instructs the Board to make releases so as “to provide all possible relief to municipal water intakes, navigation and power purposes, upstream and downstream”. The Board will balance concerns above and below the dam when it deviates. The major deviations are similar in intent to the criterion k deviations authorized by the 1956 Order but are triggered by specific Lake Ontario levels identified in the Directive rather than by the range of  water supplies to the system from 1860 to 1954.  Extreme low levels of the St. Lawrence River at Lake St. Louis near Montreal occur only when Lake Ontario levels are also very low, so a separate set of trigger levels based on downstream conditions is not required, and extreme low levels downstream will also be addressed when major deviations are triggered.   

5.  Adaptive Management Strategy

The Commission is working with the governments in the basin to develop a Lake Ontario-St. Lawrence River adaptive management strategy as an important tool for improving management of the Lake Ontario-St. Lawrence River regulation plan.   The adaptive management strategy will measure key regulation impacts to see if they are producing expected outcomes.  It is a strategy for monitoring the impacts of regulation and then using the information collected to evaluate if and how regulation might be improved over time.  It also will monitor climate and hydraulic factors that influence the effectiveness of regulation.   Data have already been collected on two key regulation impacts; the impact of water levels on wetland plant diversity and the susceptibility of shore protection structures on the south shore of Lake Ontario to damage.  The adaptive management strategy includes a list of issues that will be monitored as resources become available.

The new International Lake Ontario – St. Lawrence River Board will work with an Adaptive Management Committee to collect the data and administer the program.The new regulation plan was tested under a variety of possible future climates, including much wetter and much drier water supply conditions than those experienced in the 20th century.  If the Adaptive Management Committee finds evidence that water supplies are consistently trending wetter or drier, the Board could recommend that the Commission make changes to the regulation plan.  The Commission would apply the best tools and models available for evaluating benefits and risks and would consult with the governments and the public before changing the regulation plan. The Commission proposes an evaluation of the regulation plan not more than 15 years from the date a new plan is implemented and at appropriate similar intervals thereafter.

 The benefits of an adaptive management strategy would apply to any regulation plan, including the present one. The Commission is also considering a broader adaptive management strategy that could apply to extreme water level impacts on all the Great Lakes, including the impacts that occur despite regulation of levels.  The regional Great Lakes-St. Lawrence River Adaptive Management Plan may provide additional benefits for Lake Ontario and the St. Lawrence River.


Available as a pdf file: Overview.pdf