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This document explores the environmental considerations of water level regulation in the LO/SLR system and presents Plan BV7, a proposed regulation plan that aims to restore natural water level variation while minimizing negative impacts.
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Water Level Regulation in the LO/SLR System Environmental Considerations and Plan BV7
Background: • Boundary Waters Treaty Act of 1909 – established International Joint Commission (IJC) • IJC issued 1952 Order of Approval for the construction of the St. Lawrence River Hydropower Project • Order amended in 1956 during construction to include regulation criteria designed to reduce the range of Lake Ontario water level fluctuations, facilitate navigation on the St. Lawrence River, and provide protection for riparian and other interests downstream in the Province of Quebec.
Background: • No consideration for environmental or recreational boating interests. • Pre-regulation range approximately 7 feet. • Target regulation range between 243.29 and 247.29 feet (74.15 – 75.37 meters), recognizing that water level supplies might be outside of recorded1860-1954 range. • Water level regulation Plan 1958D operational since 1963. Frequent deviations required to adapt to changing conditions/operating experience (1958D with deviations, or “1958DD”).
Water Level Attributes Necessaryfor Sustained Ecological Benefits • Magnitude (high water/low water) • Seasonal timing • Duration • Rate of change • Long-term (15-35 year) frequency in supplies/levels
Background: The “Levels Reference Study: Great Lakes-St. Lawrence River Basin” (Report to the International Joint Commission by the Levels Reference Study Board, 1993) concluded: “The studies determined that a reduction in the range of Lake Ontario’s levels brought about by regulation of its outflows has had a significantly adverse effect on the extent, diversity, and integrity of its wetlands”. This same document concluded that Great Lakes wetlands that are flooded periodically each ten to twenty years and dewatered for two or more consecutive years between floods exhibited the greatest wetland vegetative diversity.
Background: • Wetlands are the most productive and diverse habitats, supporting hundreds of species of fish, amphibians, reptiles, birds, mammals, plants, invertebrates. • In the Lake Ontario/St. Lawrence River system, approximately 60,000 acres of wetland are negatively impacted by water level regulation. • In SLR, approximately 100 species of fish that use wetland habitats at some point of their life cycle; feeding, breeding, nursery.
Background: • Recreational angling extremely important to local economies: 2007 SLR>$33 million, Lake Ontario nearly $113 million. • Wetlands developed over thousands of years under very dynamic conditions. • Extreme highs maintained upper extent though flooding of robust emergents and upland plants; extreme lows expose accumulated sediments to oxygen aiding in their decomposition and allows for the germination of plant seeds that restores vegetative diversity to the benefit of organisms that rely on those plants.
Photo- interpretation results showing loss of meadow marsh and increase in cattail after Regulation (Doug Wilcox)
IJC Proposed Plan BV7 • 2000: International Lake Ontario-St. Lawrence River Study (5 years; $20 million) • Several proposed regulation plans developed, including “B+” (environmental plan); IJC released “Plan 2007” for extensive public review. • From environmental perspective, Plan 2007 was more harmful than 1958DD • After extensive consultation, “Plan BV7” developed.
IJC Proposed Plan BV7 • Incrementally restores more natural water level variation without disproportionate, negative impacts to other interests. • During high water supply, would raise maximum level of Lake Ontario by 2.4 inches compared to Plan 1958DD. • During low supply periods, would lower minimum lake level by 8 inches. • If approved, adaptive management practices will be employed.
