Improving the health of our ecosystems
In-stream structures are built and managed through projects such as Broken Brooks and Freshwater Mussels. In-stream structure construction and management aims to improve the health of watercourses.
To restore habitat for fish, mollusks and other animals living in our streams, one technique involves the construction of brush mats made with weaved alders and conifer boughs, as explained in the video on the right.
An alder-weaving and brush-matting structure in Jonathan Creek (Moncton)
As human impacts and development increase, instances of river crossings, barriers, and alterations also increase. Culverts are commonly installed to divert water away from roads, rail beds, and driveways to avoid pooling. However, they often alter the way our rivers flow and prevent fish passage as debris builds up. Moreover, in-stream structures such as digger logs, deflectors, and bank stabilizers that are poorly installed or have served their useful life can increase erosion and sedimentation resulting in degraded ecosystems. These segmented river ecosystems can have huge implications for aquatic organisms, particularly migratory fish species such as salmon. In 2014, the PWA established the Broken Brooks project to restore aquatic connectivity by identifying and removing barriers to fish passage. In total, roughly more than 1000 site crossing assessments have been completed (over 400 of which were culvert assessments). The PWA’s remediation efforts have included debris removals, the construction of rock weirs, outflow chute installations, and bank-stabilizing alder-woven structures.
Fluvial Geomorphology refers to the study of river processes and forms over time. This includes understanding how rivers are shaped as well as how interactions between the sediment, water, and vegetation affect aquatic structure and function. Before embarking on any remediation project, the PWA first considers the ways in which a river’s specific geomorphology may impact the success of a project. Factors such as river dynamics, erosion, sedimentation, and changes in water velocity guide the PWA’s restoration plans.
Water Guardian and Green Infrastructure
The Water Guardian project began as a way to protect our streams and rivers from the impacts of stormwater runoff and flooding. Stormwater runoff is the water from rainfall or snowmelt that can no longer infiltrate into the soil and instead will flow over surfaces, often catching and carrying harmful pollutants into our local waterways. It flows over impermeable surfaces such as roofs, parking lots, and roads. Flooding events will catch pollutants similar to stormwater runoff but often at a larger scale. To reduce these inputs, the PWA implements green infrastructure solutions. These innovative installations can take the shape of a rain garden, green roof, or retention pond to name a few. Green infrastructure can also refer to a naturally occurring area providing valuable ecological services such as a wetland.
The rain garden at Centennial Park in Moncton shortly after installation
Rain Gardens for Pollinators and Water Retention
As of 2022, the PWA has installed 17 rain gardens. Rain gardens mimic naturally found spaces that are most effective in flood mitigation and filtering stormwater runoff. Incorporating these structures creates more green spaces while aiding in the offset of carbon emissions by capturing particulate matter and providing habitat for wildlife including pollinating insects. If you would like more details on these gardens and our process, feel free to browse our Publications section for our final detailed reports on green infrastructure. You can also contact us to sign up for your own rain garden!
The rain garden at Centennial Park in Moncton several years after installation