1. Project Title: McVicar Creek Mouth Island Creation
2. Contact
Doug Geiling
Great Lakes Laboratory for Fisheries and Aquatic Sciences, Department of Fisheries and Oceans, 1 Canal Drive, Sault Ste. Marie, Ontario P6A 6W4
Tel.: (705) 942-2848; FAX: (705) 941-3025; E-mail: Geiling@ssmare.ssm.dfo.ca
3. Agencies Involved
North Shore of Lake Superior Remedial Action Plans*, 1194 Dawson Road, Thunder Bay, Ontario P7B 5E3
(* Includes Environment Canada, Great Lakes Cleanup Fund, Ontario Ministries of Natural Resources and Environment and Energy)
Department of Fisheries and Oceans, Great Lakes Laboratory for Fisheries and Aquatic Sciences, 1 Canal Drive, Sault Ste. Marie, Ontario P6A 6W4
4. Restoration Goal
Protect the mouth and shoreline to the immediate south of McVicar Creek from wave action and foster the growth and redevelopment of an historic wetland.
5. Project Type
Construction of a semicircular island with diversity in terrestrial and aquatic habitat.
6. Background and Rationale
Since 1982, the waterfront to the south of the McVicar Creek mouth has been developed into a park and marina complex. A road overpass was constructed in 1985 as part of this complex. The lakeward embankment of the overpass infilled a small wetland area adjacent to the creek mouth and hardened the shoreline.
McVicar Creek has supported spring spawning runs of at least rainbow trout (Oncorhynchus mykiss) and smelt (Osmerus mordax). More recently, low survival of young rainbow trout spawned in the creek has been attributed at least partially, to the loss of nursery habitat at the mouth.
The island was constructed in 1993 to protect the shoreline to the south of the creek mouth, and to a lesser extent the mouth itself, from wave action. The sheltered area will recreate nearshore nursery habitat and foster redevelopment of the historic wetland.
7. Regulatory Considerations
a) Completion of an Ontario Ministry of Natural Resources Class Environmental Assessment for Water Related Excavation, Dredging, and Fill Activities.
b) File a Government of Canada Environmental Assessment Review Process Screening Decision Document.
c) Obtain an Ontario Ministry of Natural Resources Work Permit.
d) Ensure rock fill added to the estuary conforms with the Ontario Ministry of Environment and Energy Lake Filling Guidelines.
8. Criteria
The basic structure should be constructed of locally available
rock and be able to withstand the erosional forces of ice and
waves. The crest elevation and width should prevent overtopping
by waves. The structure should be shaped, sized, and positioned
to protect the shoreline to the south of and including the creek
mouth, and to trap sediments transported by the creek and longshore
currents. Sufficient space between the island and mainland will
be left to maintain water circulation and prevent the formation
of a solid peninsula.
9. Project Design
Discharge from the creek is deflected to the south by a sandbar at the mouth. Longshore currents also follow a roughly north to south pattern. Thus, the island was positioned just to the south of the creek mouth.
A semicircular rock berm formed the basic structure of the island (Figure 1). This shape was chosen to enhance the likelihood of sediment deposition on the lee side of the island. To accelerate this process, semicircular and straight rock shoals were constructed on the lee side of the island. These elements also served to diversify underwater habitat which had been limited to a gradually sloping sandy silt substrate largely lacking in macrophyte growth since the construction of the road overpass.
Pockets of protected soil were built into the lee slope of the island. These pockets were placed above the waterline, and are large enough to support clusters of native shrubs and small trees. As the plantings grow, the shaded area and allochthonous inputs to the lee of the island will increase.
10. Implementation
A temporary causeway was built from just south of the creek mouth to the northernmost point of the island site. All materials were trucked to the island and shaped by backhoe. When completed, the island was 205 m long, with the northern end of the island 40 m offshore and the southern end 30 m offshore. At the centrepoint, the island is 85 m offshore. Water depth off the lee shore ranged from 1.5 to 2.8 m, not including underwater structures. The causeway was removed after completion of all structural elements of the island.
The core of the island was composed of 1-450 mm quarry run stone (approx. 11 000 tonnes), and was sloped at a 1.5:1 (horizontal:vertical) ratio from the substrate to the long-term mean Lake Superior water level. The core was overlain with 100-450 mm quarry stone (approx. 14 000 tonnes) at the same slope such that a crest 5 m wide and roughly 2 m above water level was formed. This layer was 3 m thick on the lakeward slope of the island, and 1 m on the lee slope. All quarry stone was clean, local igneous rock, which was free from silt, shale, and organic matter.
Five semicircular subsurface structures acted as sediment traps. Each was 10 m long and extended 4 m out from the island. The sediment trapping structures were constructed on top of a bed of clean quarry screenings placed at a slope of 1.5:1 such that the top of the trap was a half metre below the water surface (Figure 2a). The trapping structures were lined with filter cloth and filled to a depth of 30 cm with fine gravel (1-25 mm).
Eight rock shoals, each 5 m wide, were constructed off the lee of the island at a slope of 3:1. Each shoal contains a core of quarry screenings covered with a 1 m thick layer of 100-450 mm stone (Figure 2b).
Seven soil pockets of varying length were excavated into the lee
of the island to a depth of approximately 1.8 m, partially below
the mean water level to ensure moisture availability to the soil.
The excavated basin was lined with fine gravel and filter cloth
prior to topsoil addition (Figure 2c). Each pocket was fertilized,
seeded with a mixture of grasses, and covered with an organic,
biodegradable erosion control mat to stabilize the soil. Planting
of indigenous shrubs and small trees will follow. The lower lip
of the pockets are 0.7 m above mean lake level to help prevent
soil erosion.
11. Degree of Environmental Intervention
Culverts were installed in the temporary causeway to avoid deflection of longshore currents during construction. Mortality, while unseen, would probably be limited to the macroinvertebrate community. Given the barren homogeneity of the substrate upon which the island was constructed, this mortality was probably limited. The dumping of tonnes of rock caused a temporary, localized suspension of native sediments which was mitigated by performing all construction during winter. Ice cover prevented wave action from transporting the disturbed sediments away from the construction site.
12. Cost
Construction:
Labour and Materials $280 000
Engineering Design/Support $50 000
Contract Administration $25 000
On-Site Supervision $25 000
Subtotal, Construction $380 000
Assessment (estimated):
Field Crew (2 person weeks/year, 5 years) $7 200
Benthos Sample Sorting and Taxonomy (n=100) $5 000
Data Analysis & Reporting ($1,000/year) $5 000
Subtotal, Assessment $17 200
Total Estimated Project Cost $397 200
13. Biological Assessment
Fish using the area to the lee of the island will be monitored where possible by beach seining in spring, summer, and fall. This seining effort will be supplemented with a late summer electrofishing effort using boat mounted gear.
Benthic macroinvertebrates will be sampled using a petite Ponar dredge in each of June and October. Each effort will consist of three samples off the lakeward shore of the island and seven samples to the lee of the island. Locations will not be fixed, but will include samples from across the range of depth present.
The macrophyte community will be qualitatively sampled in the summer to monitor colonization of the lee of the island. Annual counts and identification of bird nests on the island will also be included.
All monitoring effort will be geared toward tracking changes in vegetation and fauna on and to the lee of the island over time. Assessment will be qualitative, at least over the first few years following construction.
14. Measures of Success
Maturation of the island and the area to the lee of the island is recognized as being a slow process. Thus we have not set quantitative short-term goals for this project. In the longer term, success will be estimated for a number of criteria including:
1. an increase through time in the use of the lee area by juvenile salmonids,
2. use of the area for spawning by resident fish populations (e.g., centrarchids, yellow perch),
3. reestablishment of a wetland area,
4. increased abundance and diversity of macrophyte and macroinvertebrate communities, and
5. establishment of nesting sites by birds.
Success Rating: 1
Assessment of this project has only just begun. Encouraging signs to date include the sighting of a smallmouth bass on a nest and an increase in macrophyte abundance to the lee of the island.
15. Key References
None.
Correct citation for this contribution:
Geiling, D. 1995. McVicar Creek Mouth Island Creation, p. 39-44. In J.R.M. Kelso and J.H. Hartig [editors]. Methods of modifying habitat to benefit the Great Lakes ecosystem. CISTI (Can. Inst. Sci. Tech. Inf.) Occas. Pap. No. 1.