When a lakeside bank shows active retreat, owners and managers face a choice among several stabilisation approaches. Each involves trade-offs between cost, longevity, ecological impact, and the complexity of obtaining regulatory approval. No single technique is universally appropriate — the right choice depends on the specific erosion mechanism, the bank material, the energy environment, and the applicable provincial and federal requirements.
Riprap stone revetments
Riprap — a layer of angular, interlocked stone placed along the bank face — is the most widely used hard armour technique on Canadian lakefronts. The stone dissipates wave energy through its irregular surface and transmits hydraulic forces to the underlying bank material. When properly sized and placed, a riprap revetment can protect a bank for decades with relatively modest maintenance.
Key design parameters include stone size (determined by anticipated wave height and flow velocity), layer thickness, and the specification of an appropriate filter layer beneath — either crushed stone or geotextile fabric — to prevent fine bank material from migrating through the voids in the stone.
The minimum stone size for riprap is typically calculated based on the design wave height using formulae published in references such as the U.S. Army Corps of Engineers Shore Protection Manual. On Great Lakes shorelines with significant fetch, this often results in requirements for large stone — 300–600 mm or heavier — that requires equipment to place.
Riprap does reduce habitat diversity along the bank face. The interstitial spaces between stones provide some habitat for benthic invertebrates and juvenile fish, but the continuous hard surface eliminates the varied bank habitat — overhanging vegetation, root masses, sandy beaches — that supports a range of species. Ontario's Fisheries and Oceans Canada may require offsetting habitat measures where significant riprap works affect productive fish habitat.
Retaining walls
Vertical or near-vertical retaining structures — timber, concrete, steel sheet pile, or interlocking armour units — are used where bank geometry precludes a sloped revetment, or where property boundaries limit the area available for bank works. Retaining walls transfer horizontal earth pressure to the structure rather than to a reshaped bank slope.
Steel sheet pile walls are common on Great Lakes properties where wave energy is high and space is limited. Timber crib walls — filled with stone — have historically been used on calmer interior lakes, though timber degrades over time and most jurisdictions now discourage treated wood in the water due to the potential for chemical leaching.
Retaining walls typically require engineering design and building permits in addition to any environmental approvals. They tend to have a finite service life and may require significant investment to repair or replace.
Bioengineering and living shorelines
Bioengineering uses plant material — either alone or in combination with structural elements — to stabilise a bank. The roots of native riparian plants bind soil, the above-ground structure intercepts wave energy, and the vegetation supports habitat that hard armour cannot.
Common bioengineering techniques used on Canadian lakefronts include:
- Native plant buffer strips — dense plantings of native sedges, rushes, willows, and dogwoods along the bank crest and face. These are most effective where wave energy is moderate and the primary erosion driver is surface runoff or foot traffic.
- Live staking — dormant cuttings of willow, dogwood, or other species driven into the bank face to take root. Relatively low cost and well suited to interior lakes with limited wave exposure.
- Brush mattress and fascine — bundles of branch material staked horizontally to the bank face to provide immediate surface protection while planted material establishes.
- Coir fibre rolls — biodegradable fibre logs placed at the bank toe to reduce wave attack at the waterline while bank vegetation establishes above.
Natural marsh vegetation provides a wave-dissipating buffer and habitat that hard armour cannot replicate.
Bioengineering takes time to establish — typically two to three growing seasons before native plantings provide meaningful erosion protection. On actively eroding banks with significant wave exposure, bioengineering alone is often insufficient without some structural toe protection to prevent bank undercutting while the plants establish.
Combined approaches
The most durable outcomes on exposed Canadian lakefronts often come from combining structural toe protection with native vegetation on the bank face and crest. A common sequence is:
- Place riprap or coir rolls at the bank toe to stop undercutting at the waterline.
- Regrade the bank face to a stable slope (typically 2:1 or shallower for cohesive soils).
- Install a geotextile filter where the bank material is fine-grained and susceptible to erosion through voids in the stone.
- Seed or plant the regraded bank face with native species suited to the site's light and moisture conditions.
- Maintain a dense, mown-free riparian buffer at the bank crest.
Regulatory approvals
Any bank works in Ontario require review under the Lakes and Rivers Improvement Act, and works that alter a shoreline or introduce fill near the water may require a permit from the local Conservation Authority under the Conservation Authorities Act. Federal Fisheries Act authorization from Fisheries and Oceans Canada is required where serious harm to fish or fish habitat is anticipated.
In Quebec, works on lac banks are governed by the Politique de protection des rives, du littoral et des plaines inondables, which establishes a 10- to 15-metre riparian strip within which works are restricted. British Columbia has its own Riparian Areas Regulation under the Fish Protection Act.
Timelines for obtaining approvals vary by jurisdiction and the scope of works. Engaging with the relevant authorities early in the planning process typically reduces delays.