By Corey Pelletier, Freshwater Fisheries Biologist
Trout Unlimited volunteers assess their recent work with the Division of Fish and Wildlife.
When standing on a riverbank admiring the tranquility of the flowing water, many see it for just that. Anglers stand streamside contemplating where to make the next cast. A good angler reads the water, looking for habitat that is most likely to produce a trout. Seasoned anglers know and remember the spots they have caught fish in the past, down to the rock or bank where the fish hid. However, to most, the change in a river over generations goes unnoticed.
Rivers are dynamic and constantly changing, but unfortunately, many of the changes we see today are a result of human influence. These changes are most often negative and caused by poor land use practices. Dams create barriers and discharge warm water to the otherwise cold stream below. Cattle trample stream banks causing instability, sedimentation and high nutrient run off. Clearcutting removes trees and brush which otherwise filter water before reaching a stream. And the list goes on.
Streams and rivers in Rhode Island have suffered from such practices, leaving impacted and reduced habitat for the inhabiting fish. Human influences on river habitat and water quality in Rhode Island has negatively impacted wild brook trout (Salvelinus fontinalis
) among other native fish species. We owe it to ourselves and the freshwater ecosystems that surround us to improve and mitigate these negative influences before it is too late.
That is exactly what the RIDEM Division of Fish and Wildlife (DFW) and the Rhode Island Chapter of Trout Unlimited (TU) are doing. Trees for Trout is a program started by TU in 2018, in order to restore fish habitat in the flowing freshwaters of Rhode Island. This program asks volunteers in the community to simply drop off their holiday tree after the new year. The trees are stored outside until the following summer where they are strategically used to build “conifer revetments.”
A conifer revetment is built using several Christmas trees or conifers, to protect and armor stream banks. Grouping several trees together (typically 30-80 trees), they are held in place using wooden stakes and biodegradable twine. These revetments are installed along the banks of rivers and streams extending out into the channel. The group of trees acts to slow the flow of water along the bank which causes sediment to be deposited within the revetment structure. Over time, the trees will fill in with sands and organic materials until they become filled, forming a new section of riverbank.
You may ask how this is supposed to help. In impaired stretches of river, channels often become wider than they should be and are absent of necessary habitat to support aquatic life. In these areas, banks are often eroded which further widens river channels. When banks erode, sediment is carried away by flows which fill in pools downstream. Conifer revetments act to stabilize eroding banks by slowing the flow of water and accumulating sediments. In excessively wide stream channels, during periods of low water, depth is usually shallow and consistent across a river channel, which leaves little habitat for fish. Modification is often needed to restore the natural processes of a river that has been impaired. Conifer revetments help to narrow the river channel and confine the flow so that during low flows, there is deeper water, therefore more habitat for fish.
Conifer revetments mimic natural habitat features in a river. In Rhode Island, much of the physical habitat that provides cover for fish is from trees falling into the river channel. In some cases, trees are removed or trimmed to provide passage for paddle sports. By constructing these features with conifers, we can restore habitat and re-engage the natural processes of the river. One of the most beneficial aspects of Trees for Trout is that all the work can be completed with manual labor and without the use of machinery. Many river and habitat restoration projects require extensive engineering plans and restoration to fix the impacts from construction. This project focuses on a minimally invasive procedure that can provide numerous benefits to the health of the river and local fish species.
Trees for Trout provides a great opportunity for the public to learn about river health, water quality and habitat for aquatic species. If you have a Christmas tree that you are willing to drop off after the holidays, I welcome you to contribute and come learn more about the project. Please keep in mind that habitat improvement work must be left to the professionals. A considerable amount of work goes into deciding where and how to construct these features, and should not be done by individuals. Also, a permit is required to make modifications to any waterway under the Freshwater Wetlands Act. Follow the Rhode Island Division of Fish and Wildlife Outdoor Education page on Facebook to keep informed with project updates and how you can contribute.
A revetment structure just months after installation already begins to accumulate sediment and debris, which will help to fill in the structure over time and concentrate the rivers flow into a narrower channel.