Action FF-6: Remediation of Rapids Habitat and Associated Wetlands

Current Status: UNDERWAY

BUIs Addressed: Loss of Fish and Wildlife Habitat

The Flora and Fauna Task Team examined a number of options for the remediation of rapids habitat and associated wetlands. The options listed below were designed to restore and rehabilitate habitat in order to enhance fish and wildlife populations in the AOC. The implementing organizations will examine all of these options and decide which should be implemented.
(a) Protection of remnant rapids habitat This option encompasses both the protection of remnant habitat from further reduction and degradation as well as the maximization of the productive capacity of the rapids area. In essence, this is a water quantity issue.
Water use demands in the rapids area have been prioritized by the International Joint Commission (1978) as follows: (1) shipping (ie., lock operation); (2) protection of rapids fishery; and (3) other approved uses including hydroelectric power generation. A berm was constructed in 1985 to prevent intermittent dewatering of the rapids. While the structure is largely effective, dewatering of portions of the rapids still occurs. A preliminary assessment of the extent of dewatering has been completed (see Rapids Hydrology Study above); however, the impact of dewatering on the biotic community remains to be examined.
Fisheries assessment using conventional netting in the rapids area is recognized as being either extremely difficult or impossible. A series of controlled angling efforts would, however, identify use of rapids habitat by larger fish. Conventional sampling gear could then be used in the shallow waters around the edge of the rapids to provide information on forage fish and the young of some predator species.
(b) Physical enhancement of remnant rapids habitat Berm construction represents the first attempt to enhance the remnant rapids habitat. The berm maintains a minimum level of flow along the southern shore of Whitefish Island, an area believed to contain some of the best fish spawning habitat in the rapids. The area also supports a highly productive benthic invertebrate community. The option requires the placement of additional substrate to potentially increase the size and productive capacity of the remnant rapids.
Preliminary assessment would involve mapping existing substrate composition, identifying target fish species assemblages, and noting areas likely to become dewatered under differing water supply scenarios. This information could then be used to guide substrate placement strategies.
(c) Creation of new rapids areas in the St. Marys River An alternative to enhancing or enlarging the remnant rapids would be to augment rapids elsewhere in the St. Marys River (eg., Little Rapids restoration). Areas in the river or its tributaries, which have the hydrologic and physical characteristics required to support rapids regeneration, need to be identified. Vertical drop, substrate type, streambank characteristics, the potential for ice scouring, and flow velocities are factors that must be accounted for at each site. Artificial rapids would have to be designed to incorporate sea lamprey control mechanisms.
(d) Creation of alternatives to rapids habitat A variety of methods are available to either create artificial spawning substrate or to cleanse existing habitat in order to enhance fishery production. Artificial substrate would have to have similar characteristics to a rapids area. A self-cleaning substrate system involves directing water into a bed of distribution pipes underlying a man made spawning bed, creating an upwelling through the bed. The self-cleaning system is applicable to areas with high fine sediment deposition
(e) Creation of wetlands in association with existing rapids Wetland creation downstream of Whitefish Island would connect wetland habitat to the adjacent remnant rapids. The option would involve depositing suitable fill in the area between Whitefish Island and the channel leading to the former Canadian navigation lock. Placement of boulders and rock rubble as a buffer against the fast current of the rapids would protect the site from erosion. A number of small channels could be constructed between the rapids and the new wetland to direct drifting larval fish into the wetland area.
(f) Creation of new wetlands/rapids complexes It may be possible to create a simulated rapids area in the Great Lakes Power tailrace just upstream from Fort Creek in Sault Ste. Marie, Ontario. Clean rock fill could be added to deflect most of the existing current away from the mouth of Fort Creek while the remainder of the flow would be directed over the top of the structure. Wetland features could be incorporated into the design.
A series of islands and shoals extending along a band of shallow water on the north shore of Sugar Island can also be considered for wetland development. Riffle habitat could be created by placing boulder/rubble obstructions to concentrate river flows over suitable gravel/cobble substrates. The lee of these boulder barriers might then accommodate wetland development.
(g) Enhance habitat and water quality in tributary watersheds Creating or enhancing wetlands in selected areas of tributary streams would provide a range of fish and wildlife habitats and would reduce sediment and nutrient inputs to the St. Marys River. Tributary streams provide spawning and nursery habitat for anadromous fish species, forage fish production, and linkages to terrestrial inland habitats. Removing barriers or impediments to migration, such as low head barrier dams, would also enhance fish production in tributary streams.
(h) Do nothing The Flora and Fauna Task Team recognize that this option will maintain or increase dependence on hatcheries and stocking programs to enhance fish populations in the St. Marys River.