Fish Habitat Restoration

We have expert knowledge on a wide variety of fish habitat restoration methods conducted in Atlantic Canada, from in-stream structure installation by hand to large-scale projects with heavy machinery.

Nova Scotia's waterways of all sizes have predominantly been negatively impacted by historical log drives and mill dams. This has resulted in streams and rivers becoming too wide, too shallow, and too open. Our restoration methods focus on restoring natural meander patterns, increasing pool and spawning habitat for salmon and trout, and building climate change resilience in aquatic ecosystems.

In-Stream Restoration

No two watercourses are identical, so we utilize a variety of in-stream structures and methods when it comes to restoring smaller rivers and streams.

In-stream restoration is conducted with crews of three people or more, using hand tools and small-engines and materials found in and around the stream, minimizing both the impacts and costs of these projects, while still ensuring effective, ecological restoration. Structures are installed at intervals along a stretch of stream and projects typically involve installing a dozen or more structures.

Digger Logs

Logs are installed diagonally across a stream in order to restore the natural meander of a watercourse. Softwood logs are cut from the surrounding area when possible. They are placed from bank to bank at a 30° angle and secured with rebar in a small trench in the stream bottom.

Over time, the water will dig out a cool, well-oxygenated pool below the log, while depositing the smaller sediments downstream to create gravel bars. Above the log, gravel and cobble deposits provide ideal spawning habitat for Atlantic salmon and brook trout. Digger logs replicate the impacts large fallen trees have on a stream. They are best suited for small rivers and larger brooks, typically installed in streams less than 15 meters wide.

Deflectors

Made with either logs or rocks, deflectors can be installed independently or alongside digger logs. Deflectors are triangular structures secured into the riverbank which are designed to encourage a natural meander pattern and build up gravel bars. Since each deflector is installed in a single bank, they can be constructed in wider watercourses than digger logs.

Rock Sills

Rock sills create similar habitat to digger logs. They are primarily used to hold back gravel and cobble substrate in riffle sections of stream, while improving pool habitat immediately downstream. Rock sills are installed entirely by hand using rock already present in the stream, making them a very economical and effective option. They can also be installed in wider streams than digger logs.

We also have experience installing log and rock cribs, riprap, and artificial undercut banks, as well as near-stream restoration such as riparian planting. We are always exploring new and innovative forms of fish habitat restoration that are being implemented elsewhere in North America.

Large-Scale Restoration

In larger watercourses where in-stream structures are insufficient, we use an array of large-scale structures to achieve the same habitat improvement goals as in-stream structures.

Large-scale structures typically utilize boulder and gravel, but some also implement large woody debris. Using dump trucks and excavators, material is brought to the site and typically installed in high-erosion areas. Afterwards, sites are typically planted with native riverside trees - such as willow, red maple, and red oak - in order to add stability and longevity.

Armour Rocking

Large rocks and boulders are secured into an eroding section of riverbank. Over time, sediments are captured within in the rocks, and the riverbank is rebuilt. Additionally, armour rocks encourages ice to scour out the middle of the channel, rather than the edges, increasing pool habitat.

Root Wads

Large tree roots are secured into the riverbank where they are partially submerged at all time. They provide increased fish habitat, mitigate erosion and restore riverbanks. Root wads should have riparian trees - such as willows or red maple - planted on the bank above them to assist with stability.

Rock Groynes

Similar to deflectors, groynes are triangular formations of boulder that jut into the river. As sediments build up on the upstream side, the riverbank is rebuilt, restoring the natural meander pattern. Groynes may be seeded with a grass or wildflower mix or planted with a hardy species such as willow.