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Lisa Tulen, Citizens Environment Alliance
Introduction
The Detroit River has suffered severe losses of wetland habitat since early settlement resulting in an estimated loss of more than 95% of historical wetland habitat. The Detroit River has been identified as an Area of Concern for more than 15 years, partly due to the loss of historical fish and wildlife habitat. In addressing this impaired beneficial use, the Ontario Ministry of Natural Resources (OMNR) compiled a document entitled "Survey of Candidate Sites on the St. Clair and Detroit Rivers for Potential Habitat Rehabilitation/Enhancement." This comprehensive document outlined 17 Canadian sites along the Detroit River that had potential for fish and wildlife habitat restoration and provided the rationale for Ruwe Marsh being one of the sites for future habitat restoration.
History and Characteristics
The objective of the project was to repair an existing finger dike structure at the Ruwe Marsh in an effort to protect existing habitat in an ecologically important area of the Detroit River. Despite habitat losses, the Detroit River, found within the Mississippi flyway, continues to provide habitat for 29 species of waterfowl (OMNR data 1997) and 65 species of fish (Manny et al. 1988).
Ruwe Marsh is privately owned and located in the lower Detroit River, south of Fighting Island and north of the Canard River, a major tributary to the Detroit River. This marsh complex is 580 ha (1,434 acres) in area and is composed of both a closed cell surrounded by a clay dike overgrown by trees and vegetation, and an open cell which at one time had extended around forming another closed cell of wetland. Over time this outermost dike eroded to the point where the only visible portion remaining was a finger dike extending from the north wall of the closed cell perpendicular to the river. This finger dike protected the downstream marsh vegetation along with the still existing closed cell dike and redirected the water and ice moving south down the Fighting Island channel away from the marsh.
Ruwe Marsh is the third most significant marsh in Canada for canvasback ducks, after Long Point and marshes along the eastern shore of Lake St. Clair. This is primarily due to the large stands of wild celery (Vallisneria americana), a principle food source for canvasback and redhead ducks. Wild celery, a native, submersed aquatic plant, requires specific conditions for growth. Loss of 72% of wild celery in the lower Detroit River between 1955 and 1990 coincided with the declining use of the Detroit River by diving ducks such as the canvasback duck (Schloesser and Manny 1990). Over time the existing finger dike at the Ruwe Marsh had eroded allowing strong water currents and ice to funnel through openings in the finger dike, threatening the wild celery beds in the open cell of the marsh.
Restoration
The Ruwe Marsh Restoration Project was initiated and carried out over a span of six months. Initial contact was made with a fellow marsh owner who spoke with the lessees about Ruwe Marsh. The lessees of the marsh responded with a letter showing their interest in a habitat project. The initial project description, as outlined in the Candidate Sites report, was given to the lessees of the property and the project was initiated.
Several steps were initiated in order for this project to proceed, including government approvals, funding applications, letters of support, engineering drawings, partnership agreements and tendering of the contract. It was necessary to organize the project to ensure everything occurred in a positive progression.
Several government approvals were required for the project to proceed, including a provincial Class Environmental Assessment, Federal Environmental Assessment Review Process (as Federal funds were used for the project), Fisheries Act, and Flood and Fill Regulations. Many of the approvals, such as the Environmental Assessment, required a period of public notice, while others simply required time for response from government agencies. Unfortunately, it was not possible to extend the repairs of the dike to it's original, historic form, as approval under the Navigable Waters Act was not possible.
The majority of funding for this aspect of the project came from Environment Canada's Great Lakes Clean Up Fund, now called the Great Lakes 2000 Fund. A number of partnerships provided in-kind support for this project. The Ontario Ministry of Natural Resources provided project facilitation, procured funding, prepared engineering designs, and oversaw monitoring programs. On-site construction management was provided by the Essex Region Conservation Authority. Ducks Unlimited Canada provided preliminary plans for construction of the dike.
Construction of the dike wall took place in the spring of 1995. It was difficult to pick an optimum time for construction of the dike, as the area provided habitat for an endangered species. Spring fish spawning was also a consideration. All construction material was clean and did not have excessive soil. This special consideration was outlined in the tender, and the marine construction company (Cable Marine) took great care in ensuring construction was carried out in the most responsible manner possible.
Due to the delicate state of the existing dike, it was likely that if construction had not been carried out at that time it was extremely likely that the dike would not survive another winter and would require more extensive and much more costly repair. Construction was tendered out to a local construction company and administered by the OMNR tendering process.
Effectiveness and Further Steps
Ruwe Marsh Restoration Project resulted in the repair of 1,125 m (1,230 yds) of deteriorated dike protecting 366 ha (904 acres) of downstream wetland as well as providing additional protection to the dike walls of the enclosed wetland. Follow-up monitoring at Ruwe Marsh included Global Positioning System (GPS) mapping of existing wetland vegetation, and fish and wildlife inventories. Fish monitoring at the Ruwe Marsh following dike reconstruction, showed an increase in the number of fish species from 24 in 1994 to 36 in 1995. Fish species recorded included three classified as 'vulnerable' by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC): the pugnose minnow (Notropis emilae), spotted sucker (Minytrema melanops) and the greenside darter (Etheostoma blennioides). This is the first record of the greenside darter in the Detroit River. Marsh bird monitoring was initiated at the Ruwe Marsh in 1995 by a local volunteer from the Essex County Field Naturalist Club and continues to provide valuable information on the importance of the marsh to migrating and nesting marsh birds.
As purple loosestrife (Lythrum salicaria) was the predominant species in the enclosed part of the marsh, Ruwe Marsh was included in the University of Guelph's purple loosestrife biological control program. Gallerucella sp., a leaf eating beetle, was introduced in the marsh in hopes that this species would proliferate and provide a means of biological control for purple loosestrife.
In the years following dyke repair, the OMNR recorded the highest number of waterfowl species (29 in 1997) and the highest counts of canvasback ducks (17,711 in 1996) and redhead ducks (10,965 in 1997) for the lower Detroit River, Lake St. Clair and Rondeau Bay area since surveys were initiated in 1987 (Chatham OMNR).
Currently, canvasback duck populations in Ontario are higher than they have been for years and biologists are predicting a recovery in wild celery beds in the Detroit River. The reconstructed dike walls at the Ruwe Marsh are now covered in newly established vegetation. Ruwe Marsh remains a significant habitat for a large and diverse community of waterfowl, as well as fish and other wildlife due in large part to the repair of the dike.
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