February 1, 2019 at 4:20 pm
By Merry Gallagher, Native Fish Conservation Biologist
Historically, many Maine streams were used to transport logs from the woods to the mills. To increase the efficiency of moving the logs, boulders, in-stream logs and other habitat features were removed, stream channels were often bulldozed and straightened to facilitate log transport, and side channels and flood plain access would be blocked or bermed. These operations degraded trout habitat by decreasing the overall quantity and quality of pools, removing in-stream structures and cover elements beneficial to fish, and altering substrate composition. Intervale Brook is in Frenchtown Township and is about a four-mile long, steep tributary to First Roach Pond. Intervale Bk is a historic log driven stream that shows evidence of channelization and fish habitat degradation due to past bulldozing, berming and removal of instream features such as boulders. In addition, an old splash dam constructed to facilitate log driving many years ago was still present in the headwaters of the stream and was a complete barrier to natural fish movements.
A private landowner, along with the Maine Department of Inland Fisheries and Wildlife, Maine Forest Service, and Forest Society of Maine identified Intervale Brook as a good candidate for fish habitat improvement through stream restoration. After surveying approximately 3.5 miles of the stream, a two-year restoration plan was formed where several blocked side channels were identified to be reconnected to the main stream channel, in-stream wood and boulders were added where possible, and the remnant splash dam was removed over a two-year project period (2012-2013). In the fall of 2012, an approximately 2-mile section of the stream was treated where 8 previously bermed and blocked side channels were reconnected to the main channel of Intervale Brook, many boulders that were up on the stream banks were rolled or placed back into the stream, and several large, intact trees in close proximity to the stream were pulled down into the channel but remained anchored to the stream bank by their root wads (Figure 1).
[caption id="attachment_3339" align="aligncenter" width="500"]
Figure 1. A ‘key piece’ of large wood added during Phase 1 of the project. The tree is pulled down and into the channel while leaving a root wad attachment with the stream bank. On a steep stream such as Intervale Bk, maintaining a connection with the stream bank helps keep large key pieces of wood stable enough to facilitate the collection of smaller wood pieces moving downstream and setting up the stream processes that assist with pool formation and fish habitat cover elements.[/caption]
Phase 2 of the project occurred in the fall of 2013, where additional wood was added to the 2-mile treatment section through a ‘chop and drop’ procedure and the splash dam at the headwater was removed (Figures 2 and 3).
[caption id="attachment_3342" align="aligncenter" width="500"]
Figure 2.[/caption]
[caption id="attachment_3341" align="aligncenter" width="500"]
Figure 3. The same site after splash dam removal and boulder addition. Brook Trout now have free access to high quality upstream habitat and thermal refuge. Boulders are returned to the stream channel to provide cover elements for fish, encourage natural scouring around them to provide ‘pocket pools’, and to provide additional anchoring structures for smaller, mobile wood as it is transported downstream. These actions contribute to natural pool formation over time.[/caption]
We have been monitoring the stream for biological and physical changes due to these treatments through annual sampling events ever since. We have four sites along the length of the stream where we conduct annual stream electrofishing and fish habitat condition surveys. The upper most site is above the location where the splash dam used to be and no habitat improvement treatments have occurred. There are two sites within the 2-mile long treated section where side channels were re-connected, boulders and other habitat elements were added and ‘chop and drop’ occurred, and there is also a fourth monitoring site below where any habitat improvement treatments occurred. Wild Brook Trout abundance has been positively responding ever since the project was implemented (Figure 2). All in all, this has been a rather positive project overall and the resident Brook Trout seem to approve!
[caption id="attachment_3344" align="aligncenter" width="600"]
Figure 4. Annual numbers of adult wild Brook Trout collected by electrofishing at four monitoring sites along Intervale Brook. Overall, Brook Trout numbers have increased at all monitoring sites since the completion of the habitat improvement treatments. The ‘Above’ site is located above the location of the now removed splash dam and its previous impoundment. It is a small, high quality headwater stream that did not bear the scars associated with past log driving, bulldozing or berming although the presence of the dam very likely prevented any Brook Trout from re-accessing this area if they dropped over the dam. Brook Trout now have free access to this headwater during low flow and thermally stressful times and appear to be using it quite effectively.[/caption]
Figure 1. A ‘key piece’ of large wood added during Phase 1 of the project. The tree is pulled down and into the channel while leaving a root wad attachment with the stream bank. On a steep stream such as Intervale Bk, maintaining a connection with the stream bank helps keep large key pieces of wood stable enough to facilitate the collection of smaller wood pieces moving downstream and setting up the stream processes that assist with pool formation and fish habitat cover elements.[/caption]
Phase 2 of the project occurred in the fall of 2013, where additional wood was added to the 2-mile treatment section through a ‘chop and drop’ procedure and the splash dam at the headwater was removed (Figures 2 and 3).
[caption id="attachment_3342" align="aligncenter" width="500"] Figure 2.[/caption]
[caption id="attachment_3341" align="aligncenter" width="500"] Figure 3. The same site after splash dam removal and boulder addition. Brook Trout now have free access to high quality upstream habitat and thermal refuge. Boulders are returned to the stream channel to provide cover elements for fish, encourage natural scouring around them to provide ‘pocket pools’, and to provide additional anchoring structures for smaller, mobile wood as it is transported downstream. These actions contribute to natural pool formation over time.[/caption]
We have been monitoring the stream for biological and physical changes due to these treatments through annual sampling events ever since. We have four sites along the length of the stream where we conduct annual stream electrofishing and fish habitat condition surveys. The upper most site is above the location where the splash dam used to be and no habitat improvement treatments have occurred. There are two sites within the 2-mile long treated section where side channels were re-connected, boulders and other habitat elements were added and ‘chop and drop’ occurred, and there is also a fourth monitoring site below where any habitat improvement treatments occurred. Wild Brook Trout abundance has been positively responding ever since the project was implemented (Figure 2). All in all, this has been a rather positive project overall and the resident Brook Trout seem to approve!
[caption id="attachment_3344" align="aligncenter" width="600"] Figure 4. Annual numbers of adult wild Brook Trout collected by electrofishing at four monitoring sites along Intervale Brook. Overall, Brook Trout numbers have increased at all monitoring sites since the completion of the habitat improvement treatments. The ‘Above’ site is located above the location of the now removed splash dam and its previous impoundment. It is a small, high quality headwater stream that did not bear the scars associated with past log driving, bulldozing or berming although the presence of the dam very likely prevented any Brook Trout from re-accessing this area if they dropped over the dam. Brook Trout now have free access to this headwater during low flow and thermally stressful times and appear to be using it quite effectively.[/caption]Categories