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General Notes on Graphs and TablesBasin Map

In order to show a true comparison of the water levels that would result from the different regulation plans, each graph or table uses a standard set of water supply conditions. In some cases these are the recorded water supplies. In other cases, a "stochastic supply sequence" that has been statistically generated from recorded supplies to test plan performance with a wider range of supplies.

The current approach to regulation includes Plan 1958-D along with frequent deviations from the flows indicated by this plan. These deviations have depended on Board members' judgment, which has changed over time as the Board has gained more experience with regulation. To allow for true comparisons using different water supply conditions, a model called Plan 1958-DD has been developed that incorporates Plan 1958-D and the general practices followed by the Board when deviating from plan flows. Water levels shown for Plan 1958-DD in the graphs and tables for the 1900-2000 period are not actual recorded water levels, but rather simulations. Water levels shown for Plan 1958-DD for the 2001-2011 period are the actual recorded levels.

The unregulated water levels shown in the graphs and tables are based on Plan E, which was developed by the International Lake Ontario-St. Lawrence River Study. Under Plan E, the dam would be operated to replicate the flows that would have occurred without the dam, except for operations during ice formation that would be impossible to model under natural conditions. The new regulation plan attempts to move more toward natural flow patterns while continuing to reduce the frequency and severity of the most extreme water levels that would have happened with no regulation. Unregulated flows and Plan 1958-DD are shown in the graphs and tables to show how Plan Bv7 balances these objectives.

The regulation plan influences still water levels, or the levels that would occur on the lake and river with no effects from wind or waves. All of the water level graphs and tables show the still water levels that the different regulation plans would produce. These results depend routing a defined set of water supplies through the physical system. So while future water supplies are uncertain, the levels that would result from a particular set of water supplies have a high degree of certainty. The analysis based on economic and environmental performance indicators includes additional information, such as the probability that a storms will occur and the economic value of resulting impacts. This provides a more complete picture of the types of risk associated with the different plans, but introduces greater uncertainty.

Average Water Levels Graphs: 101-Year Supply Sequence

Plan Bv7, Plan 1958-DD and Unregulated Levels

 

Lake Ontario
Alexandria Bay
Ogdensburg
Long Sault
Pointe Claire
Montreal
Lac St. Pierre

These graphs show the average water levels that would occur under Plan 1958-DD, Plan Bv7 and unregulated levels at different times of the year. In order to compare the plans, each was run with the standard set of recorded water supplies from the Twentieth Century (1900-2000). The graphs do not show the average levels for Plan 1958-DD during the years the plan was in effect (1960-present).

Download All Average Water Levels Graphs

Water Levels Graphs: 101-Year Supply Sequence

Plan Bv7, Plan 1958-DD and Unregulated Levels

 

 

Lake Ontario 00 10 20 30 40 50 60 70 80 90
Alexandria Bay 00 10 20 30 40 50 60 70 80 90
Ogdensburg 00 10 20 30 40 50 60 70 80 90
Long Sault 00 10 20 30 40 50 60 70 80 90
Pointe Claire 00 10 20 30 40 50 60 70 80 90
Montreal 00 10 20 30 40 50 60 70 80 90
Lac St. Pierre 00 10 20 30 40 50 60 70 80 90

These graphs compare the simulated water levels for Plan 1958-DD, Plan Bv7 and unregulated levels using the recorded water supplies for each decade in the Twentieth Century. The Plan 1958-DD levels are simulated and are not the actual recorded levels.

Download All Water Level Graphs

Water Levels Graphs: 2001-2011 Supply Sequence

Plan Bv7 and Actual Recorded Levels

 

 

Lake Ontario 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
Pointe Claire 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

These graphs compare the actual recorded water levels from 2001-2011 and simulated water levels for Plan Bv7 using the same water supplies. The simulated Plan Bv7 levels were reviewed on a week-by-week basis to include flow adjustments and deviations from the plan flow that the IJC Board would likely have made in response to actual circumstances during this time period. Differences in peak elevations and beginning of October elevations are noted for each year.

Download All Water Level Graphs

Water Levels: "Spaghetti Graphs"

Plan Bv7, Plan 1958-DD and Unregulated Levels

 

Lake Ontario Plan 1958 DD Plan Bv7 Unregulated Levels
Alexandria Bay Plan 1958 DD Plan Bv7 Unregulated Levels
Ogdensburg Plan 1958 DD Plan Bv7 Unregulated Levels
Long Sault Plan 1958 DD Plan Bv7 Unregulated Levels
Pointe Claire Plan 1958 DD Plan Bv7 Unregulated Levels
Montreal Plan 1958 DD Plan Bv7 Unregulated Levels
Lac St. Pierre Plan 1958 DD Plan Bv7 Unregulated Levels

These graphs show a visual comparison of the variability in water levels that would occur under Plan 1958-DD, Plan Bv7 and unregulated levels. Each colored line represents the levels that would occur in a single year with recorded water supplies in the Twentieth Century. The levels for each plan are simulated and are not actual recorded levels.

Download All "Spaghetti Graphs"

Water Level Tables: 101-Year Supply Sequence

Plan Bv7, Plan 1958-DD and Unregulated Levels

 

Lake Ontario
Alexandria Bay
Ogdensburg
Long Sault
Pointe Claire
Montreal
Lac St. Pierre

These tables compare how often water levels would be above specific elevations for Plan 1958-DD, Plan Bv7 and unregulated levels. The tables show the simulated water levels for each plan using the recorded water supplies for the Twentieth Century.

Download All Tables

Water Level Tables for Boating Season: 101-Year Supply Sequence

Plan Bv7, Plan 1958-DD and Unregulated Levels

 

Lake Ontario
Alexandria Bay
Ogdensburg
Long Sault
Pointe Claire
Montreal
Lac St. Pierre

These tables compare how often water levels would be above specific elevations during the boating season for Plan 1958-DD, Plan Bv7 and unregulated levels. The frequency within the desired range of levels for boating, as determined by the Lake Ontario-St. Lawrence River Study, is also shown. The boating season is defined as April 15-October 15. The tables show the simulated water levels for each plan using the recorded water supplies for the Twentieth Century.

Download All Tables

Environmental and Economic Performance Tables

Plan Bv7, Plan 1958DD and Unregulated Levels

 

Environmental Performance Table: 101-Year Supply Sequence
Economic Performance Table: 101-Year Supply Sequence
Economic Performance Table: Stochastic Supply Sequence

These tables compare the environmental and economic performance of Plan 1958DD, Plan Bv7 and unregulated levels. The analysis relies on models and data sets developed during the International Lake Ontario-St. Lawrence River Study, with some modification and additions since the study took place.

The environmental performance indicators integrate extensive data on how ecosystems respond to patterns of water level fluctuations. Recorded water supplies for the Twentieth Century were used to simulate water levels. Plan 1958-DD is used as the basis of comparison. Positive changes are shown in blue while negative changes are shown in red. Values shown in grey were considered to show no significant change.

The economic performance indicators integrate extensive data on each user group, and how they are affected by various risk factors such as water levels and storms, into a single dollar value. The tables compare the change in economic benefits that would result from Plan Bv7 and unregulated levels, using Plan 1958DD as a basis of comparison. Increases in benefits compared to Plan 1958-DD are shown in blue while decreases are shown in red. Recorded water supplies for the Twentieth Century were used to simulate water levels in the 101-year sequence. The stochastic water supply sequence was statistically generated from recorded supplies. It includes periods that are wetter and drier than the recorded supplies.

 

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