The North Country has been fortunate.
Western states have earthquakes, while the southern states have twisters. The Eastern Seaboard and the Gulf of Mexico are pummeled by hurricanes, Hawaii faces volcanoes and Alaska experiences both volcanoes and massive earthquakes. Even the Midwest has been deluged with floods for centuries.
Until recently, the North Country has been relatively immune to regular shows of natural destruction. The region's apparent invulnerability has worn off over the past few decades, but not because of any change in nature's providence. The increasing rate of flooding on Lake Champlain has been brought about because of human interventions.
To better understand the flood regime change the North Country has experienced in its recent history, past precipitation, temperature and lake-level data must be better understood and incorporated into lake-level management decisions.
Climatic influences
The region is experiencing climate change. While the scientific community broadly agrees that the earth is experiencing an upward warming trend, there is also almost universal agreement that the current cycle is both accelerated and exacerbated by carbon dioxide emissions brought on by the Industrial Revolution.
The dramatic increase in global economic development, especially over the past two decades, has accelerated global warming to a degree that forces scientists to almost constantly revise upward their predictions for the coming century.
These global climatic changes may have affected the pattern of temperatures and precipitation in the North Country.
Temperature Trends
Past temperature data over more than a century demonstrate that regional temperatures fluctuate, but over a relatively narrow range. The 10-year moving average shows that the region is experiencing a continuing warming trend that, by 1999, surpassed any peak experienced over the last 100 years.
Time will tell whether this trend will continue. Most scientists believe it will, and conclude that these higher temperatures will bring about an earlier and more intensive snowmelt that gives rise to more intense spring lake flooding.
Precipitation Changes
Annual precipitation in the Champlain Valley, as measured at Burlington, Vt., has varied from 21 inches to 50 inches over the past 119 years. The graph with this story shows that variability in rainfall is natural.
Superimposed on the graph of annual precipitation is a 10-year moving average that removes some of the annual variability and better demonstrates emerging trends. This moving average held consistently between 30 inches and 34 inches per year until 1976. After 1976, the moving average has rarely fallen below 34 inches and recently exceeded 40 inches for the first time. The region is experiencing about 15 percent greater rainfall, and this trend continues to rise.
lake level science
The combination of greater precipitation and more pronounced variability in snow melting affects the lake in subtle ways that have caused the flooding increasingly experienced on Lake Champlain.
The moving average level of the lake remained in a range between 95.25 and 96.25 feet from 1920 to 1970. After 1970, the annual level began to trend upward quite dramatically, and rose to between 96.25 and 96.75 feet. Another upward trend began in the late 1990s, in correlation with a rise in annual precipitation. A statistical analysis shows that the lake level averaged 95.7 feet until 1969, rose to an average level of 96.3 feet after 1970, and rose further to 96.7 feet after 1999.
However, accurate modeling of the lake level must take into account three dimensions. First, the average outflow of the lake depends on the average lake level. Second, the seasonal variability in precipitation and snow melt also affects the variability of the lake level in subtle ways. Finally, any constrictions in the Richelieu River affect both the average and the peak lake level.
The drainage rate of Lake Champlain is proportional to the height of the lake. The graph with this article shows the correlation of drainage through the Richelieu River in kilocubic feet per second depending on the level of the lake.
An analogy to lake height is that of a bathtub. If the drain is not fully open, the tub will continue to fill up even if the water tap is turned down to halfway. A constricted Richelieu creates a complicated dynamic relationship between precipitation and lake height. In essence, the river constriction is the controlling and the determining factor, with precipitation the minor rather than the major partner.
shoals affect outflow
The relationship between lake level and the Richelieu drainage rate shows that at the peak of the 2011 flood, the river flowed at more than 60,000 cubic feet per second. Shoals in the Richelieu River act as a natural weir that prevents outflow if the lake level falls below approximately 91.3 feet.
The lake level maintains an average height, which rises with average precipitation but also rises as the constriction of the Richelieu River increases.
An increase in average precipitation moves the entire relationship up proportionally, while an increase in the volatility of precipitation exaggerates both the highs and lows proportionately. However, further constriction of the Richelieu River both increases the mean height and exaggerates its volatility.
The level of the lake has risen and has become more volatile likely because of a perfect storm of higher average precipitation, greater precipitation extremes and, especially, increased constriction of the Richelieu River.
Flooding and ecology
These increased flood events began first in the early 1970s and increased since then as precipitation increased and spring melts arrived earlier. Complete daily lake-level data was maintained since the summer of 1939. The lake typically experiences its peak level in April and May of each year. Before 1970, the lake level never exceeded 100.82 feet. Since then, it has exceeded that level 11 times. The lake is flooding much more frequently and to a greater height since 1970.
A report from last year commissioned by The Nature Conservancy of the Adirondacks and of Vermont pointed out that more extreme runoff is beginning to damage the lake ecosystem. With floods and greater runoff comes greater phosphorous and chemical release from farmland and overrun sewage-treatment plants.
This greater pollutant loading in the lake produces dangerous algae blooms that can be fatal to fish and to animals dependent on the quality of Lake Champlain water. They also produce more weeds in the Richelieu that further constrict the river. In addition, more extreme lake events also place in jeopardy the natural locations of lake-life egg beds and may harm subsequent fisheries.
Economic damages
While it is exceedingly difficult to determine the economic costs from loss of lake biodiversity or fisheries, or the risks associated with poisonous algae blooms, human property costs are easier to tally. With the declaration of flooding as a federal disaster, municipalities and nonprofit agencies in counties bordering the lake are in the process of filing damage claims.
Preliminary estimates of municipal and agency damages already tally in the millions of dollars. The state of Vermont is also offering low-interest loans to businesses damaged by flooding and has already spent more than $1 million on that program. However, the damage along approximately 500 miles of lake shoreline will likely tally in multiple tens of millions of dollars of damage for this year's flood event alone.
Canadian communities in the upper Richelieu River have also suffered. An estimated 3,000 homes in Quebec have been flood damaged. This flooding will also likely tally in the tens of millions of dollars.
lake levels control
Flooding of Lake Champlain has become commonplace since 1970, even though it was exceedingly rare before that date. Substantial flood damage in the early 1970s induced the governments of the United States and Canada to request that the International Joint Commission investigate the feasibility and desirability of Richelieu River flow regulation to prevent future flooding.
The IJC has the responsibility for negotiation of water issues that span the U.S.-Canada border. It oversees the shared water bodies of the Great Lakes, rivers in British Columbia that flow south, and the Richelieu River that spans the border between New York, Vermont and Quebec and drains Lake Champlain north into the St. Lawrence River. The commission conducted engineering and economic analysis and public hearings over the issue of river flow and lake-level management in the mid-1970s. They released their report in 1981.
The report concluded that river and canal development in the early 1970s led to flooding problems in that decade. The commission recommended that flow through the Richelieu River should be managed to alleviate future economic and ecosystem damage. However, the commission also recognized that some who testified at public hearings were very much opposed to any management of the lake level. Consequently, the commission recommended that "(while) it is technically feasible to operate a gated structure at St. Jean that accommodates the proposed environmental criteria, the commission was unable to determine the desirability of the gated structure and therefore was unable to make recommendations regarding the regulation of Lake Champlain and the Richelieu River. However, the commission does recommend that a flood forecasting and warning system be instituted as soon as practicable and that flood plain regulation be implemented by the appropriate jurisdictions as a matter of urgency."
The commission concluded that the level of the lake was not a technical problem. Indeed, they outlined a number of solutions, from water-management gates on one extreme to limited dredging and better management of canals and locks on the other. However, they were unwilling to inject themselves into the politics of lake-level management.
benefit/cost analysis
The commission recommended dredging portions of the Richelieu River and that the cutting of a channel in shoals in the Richelieu could partially offset constrictions that occurred when the Chambly Canal was widened and riverside development constricted flow, dredging had gone in abeyance, and flood plains were lost to development and agricultural reclamation. They also observed that agricultural and sewage runoff was giving rise to greater weed growth in the Richelieu, which further restricted river flow and exacerbated spring flooding.
The commission recommended a number of solutions. Common among all solutions is the cutting of a 700-foot-wide, 8,000-foot-long channel in the St. Jean shoal to a depth of about six feet. In 1977, the cost of this remedy was estimated to be $3.3 million, which is equivalent to $9.7 million today.
Following that investment, the Fryers Dam downstream from St. Jean could be used to prevent the lake level from becoming so low that it would threaten the lake ecosystem. They also proposed a water gate at St. Jean that could be used to manage the lake level even more precisely. The combination of dredging and channel widening, and a water gate, could be used to regulate the river in a way that mimicked past river heights before development and climate change took their toll.
However, despite the favorable benefit/cost analysis determined by their study, the commission's recommendations were not adopted.
It is interesting to note that the estimated $9.7 million equivalent cost in today's dollars for the cutting of a channel in the shoals would have avoided tens of millions of dollars in damage to property on Lake Champlain and the Richelieu River in 2011 alone. However, even a casual inspection of flood trends demonstrates that these problems will continue, and may even accelerate, if officials fail to adopt what the International Joint Commission recommended 30 years ago.
Conclusion
Not all agree that the lake level should be managed. Nature cannot be denied for long, and to try to affect its path often results in unintended consequences. Such public sentiments induced the IJC to conclude that management of the level of the lake is primarily a political issue. The science, economics and technology of flood management all commend to the prudent use of available tools to create a sustainable lake ecology and also protect humans from property damage and potential loss of life.
However, the IJC was unwilling to propose active lake management in the face of a very vocal group of individuals who doubted the soundness of human intervention in the level of the lake.
Perhaps there is now a greater consensus around active lake-level management, especially management that avoids the catastrophic flooding that is growing likely and increasingly costly to the economy and the ecology on both sides of the U.S.-Canada border.
Colin Read is the chair of the Department of Economics and Finance at SUNY Plattsburgh. He has degrees in law, economics, physics and business. His regular column can be found every Sunday in the Plattsburgh Press-Republican newspaper.
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