Restore the natural rhythms of a Great Lake

1. Restore the natural rhythms of a Great Lake • Historic opportunity to improve the environment of Lake Ontario • net economic benefits

3. Regulation in place since 1960 • Current regulation plan – Plan 1958DD • Three original interests: hydropower, shipping, municipal water • Present study engages three new interests: recreational boating, shoreline property, the environment A regulation plan is a set of rules for water releases through this dam and subsidiary dams

4. Plan 1958DD began in 1960. Prior to regulation, Lake Ontario exhibited natural cycles of low and high water levels, based on climatic cycles.

5. Regulation has stabilized the lake, affecting wetlands and coastal habitats in both the lake and river. If we saw a flat-line like this in a hospital monitor, we’d be rushing in with resuscitation equipment!

6. Change the hydrology – change the biology. • Worldwide literature highlights these results of altered hydrology: • competitive dominance by robust emergent plants • reduced species diversity • increased susceptibility to invasive species • exclusion of keystone species

7. Hydrologic alteration, as a result of regulation, has had big effects on wetlands. • Extensive bluejoint wet meadows have declined in area over 50% since early 1960s. • Cattail-dominated marsh has expanded in response to stable water levels – reducing diversity of species and natural communities in wetlands. Before regulation – Bayfield Bay, Ontario After regulation – Bayfield Bay, Ontario Maps from aerial photos courtesy of Canadian Wildlife Service, Ontario Region

8. Diverse coastal plant progression Emergent Marsh Submerged Plants Meadow Marsh Upland During extended droughts, cattail, which can dominate emergent marsh, is dewatered too long and it dies off. LOSL surveys found little or no cattails at elevations that had not been flooded for five years or more.

9. Virginia rail: indicator of shallow emergent marsh • Black tern: indicator of deep emergent marsh Both species reproduce much more successfully under more natural hydrologic conditions, and are representative of the success of other wetland-dependent species.

10. Northern pike prefer to move into wet meadows during the early spring to spawn. Cattail-dominated marshes deny access to wet meadows. Northern pike populations in Lake Ontario and the Upper St. Lawrence are declining rapidly. Three plans were considered by the IJC – A, B, D.

11. How closely does Plan B mimic the natural hydrologic pattern of the lake? Pre-regulation “plan” Plan B on average results in lower water levels Plan B closely follows the natural pattern of the lake Plan D results in a very different average year

12. Economic Impacts of Candidate Plans – 50,000 year stochastic time series

13. Key points • IJC has an historic opportunity – net benefits • Plan B an excellent, creative compromise – balanced benefits and costs • Plan B – a big step for the environment • Plan B based on strong science – models and conclusions consistent with worldwide literature • Shoreline erosion is a fact of life in all plans – Plan B somewhat more rapid, but costs per structure do not appear disproportionate • Seize the opportunity for a big step toward restoration