2024 Bennery Brook Stream Restoration Report

• August 29, 2024
• Maria MacHattie
• Madison O’Callghan

Introduction

Bennery Brook is a third order stream located in Enfield NS, west of highway 102 (44.924637, -63.53605). This stream can be accessed through a small path in the woods just off Exit 7 heading south. Bennery Brook’s drainage area extends from Bennery Lake to Halifax Stanfield International Airport, with its mouth connecting to the Shubenacadie River. The stream exhibits a moderate slope throughout its length and flows along side a wetland directly adjacent to the highway. This brook was rerouted in the 1970’s to accommodate the construction of Highway 102. Because of this re-routing, the ecosystem of the brook had been severely damaged, leaving a simplified stream with little aquatic life.

Over the past 8 years, SWEPS has installed 7 digger logs to this location to increase the formation of pools and meanders to this stream. According to one of the local residents, the stream looks completely different from before the digger log installation and more life has returned to the area.

Surrounding life

In terms of residential development, few houses are located near this brook. A small farm with a few horses and donkeys is located directly west of the site location. The pasture for the animals extends alongside a portion of the brook, laying within its floodplain. Aside from this farm and the highway, only small amounts of development along Grant Rd. surround the area of the site location. Upstream and south of the site there is a beaver damn which is suspected to have created or enhanced about a twelve-acre wetland (44.90452° N, 63.53554° W).

A Blue Herring has been spotted perching on tree branches along the site, likely looking for fish. There is also evidence of a Woodpecker in the area, but it is yet to be seen by the team members. A Wood Cock, a Merganser Duck, a Mink and a few Robbins were also spotted in the area. The site was abundant with Stone flies, Dragonflies, Wolf spiders, frogs and Catus fly larva. A yellow garden spider was also found in the wetland that runs along the brook. Multiple different types of fish were spotted in Bennery such as Chub, Brown Bullheads, Minnows, a few Stripers, as well as Trout ranging from fry to juvenile. The crew also found an empty muscle shell in the area.

The canopy coverage along the site location ranged from 20% to 90%. Most of the trees in the area are deciduous, including Ash, Maple, Birch, Choke Cherry trees, and a few Popple. In terms of the few coniferous trees present, there were a couple Pine and a few Fir. The crew also spotted a single Bog Orchid upstream from the first digger log.

Observations

Bennery Brook lies on a wide floodplain and had been substantially over widened in attempts to prevent flooding during highway construction in the 70’s. Berms have also been built along the length of the brook, likely because the over widening was not enough to stop the floods. The impact of these structures left the brook simplified and with no thalweg. The berms also push the floodwater into the pasture of the nearby farm. Blast rock from a nearby quarry has also replaced the streams original bed, leaving only jagged rocks lining the brook. After a conversation with the man who owns the farm, he noted that there once was a pool in the area deep enough for swimming that was now filled in with this rock. He had even previously painted multiple rocks to observe how much they moved in a season which confirmed the drastic movement of this rock.

On June 21^st, 2024, the field crew, consisting of Robert Perkins, Tom Mills, Maria MacHattie, and Madison O’Callaghan visited the site location. When the crew arrived, it was immediately noticeable that the two digger logs in this area needed repairs as they had previously been washed out. There were also large amounts of iron settled at the bottom of pools along the brook. Towards the bridge that runs below the highway, there was many spots with visible manganese along the bank. Additionally, it was noted that the small wetland along the eastern side of the brook could be further developed to aid in storing flood waters.

On August 5^th, during a heavy rain, Robert Perkins visited the site location to observe how long it took for the rain to drain into the river. He relayed back to the crew that it took three hours for this process to occur. The next day the crew visited the site and Tom Mills stated that the water was much more turbid than normal. The crew then ventured upstream to see where this silt was coming from. They visited two culverts along the side of the highway. The first culvert visited (44.90540° N, 63.53242° W) had no water running through, and the brook below was dry. The second culvert (44.89423° N, 63.52738° W), used to collect runoff from the airport, was running quickly with very turbid water, concluding the origin of this silt.

Turbidity samples were taken at both culverts as well as the first digger log. The reading taken from the first log was 21.7 NTU, the reading from the first culvert was 1.51NTU, and the reading from the second culvert was 23.0 NTU.

As the crew was working in the brook, they spotted two dead Bullheads and one dead trout. The trout was likely killed by a bird as it had visible wounds on the outside of its body, but the cause of death of the catfish is unknown as they presented no visible injuries. The crew also spotted a dead beaver on the side of the highway by the first culvert mentioned above. After further observation it was concluded that although the beavers could enter the culvert on the airport side of the highway, they could not enter on the brook side because the culvert had been placed too high to allow passage.

Restoration Work

On July 4^th, repairs on the first log began. The crew had decided that since the washout underneath the Digger log was so deep, they would place a smaller log beneath the original log to provide a sturdier ramp. After this log was placed, moss and leaf litter were used to seal the cracks off. Rocks and sand where then used to create the ramp along the back of the log. The same process was used for the second log.

After a heavy rain both logs were washed out. The areas where the smaller logs were placed were still intact, so the crew decided to add more in the washed-out areas. The same materials were used to repair both logs and they ended up holding quite well. A small groove was also cut out of the first log to allow more flow in low water conditions.

In 2023, after the July floods, Robert Perkins noticed a large hemlock had washed up onto the bank of the stream. He decided that it would make a nice digger log, so he tied it to another tree with a cable to hold it in place for the coming year. On July 23^rd,2024, the placement of this log began (44.91789° N, 63.53897° W). The log was too heavy for the crew to carry themselves, so they used a block and tackle as well as a come-along to set it in place. The block and tackle were first used to hoist the log into the air so it could be turned to lay across the brook. Once the log was in this position, a come-along was used to pull the log out of the way so the team could begin digging the trench. After the trench was dug, the log was hoisted yet again and placed onto smaller logs to make sliding it into the trench easier. Large sticks were then used to pry at the log until it was in place and the team began to construct the ramp. Moss, rocks, leaf litter, and sand were also used for this process. Rocks were also piled on each end of the log to promote bank stabilization. After another heavy rain this log as also washed-out underneath, so the team used the technique of placing a smaller log beneath the main log and filled in the hole.

Downstream from this log the crew had previously seen a trout laying on its side in attempt to move upstream through a very shallow riffle (about 2cm in depth). The crew decided to redirect the stream from this area and created a deeper channel with a developed thalweg. To ensure the stream did not go back this way during high flow, a deflector made of trees from a debris jam was installed. These trees were pinned in place with rebar, and rocks were piled on the front and back to further block water passage. Large rocks from the stream bed in this area were also removed to expose gravel that could be used as spawning beds. A small digger log was placed at the top of this channel to push the water into the bank in hopes of developing an undercut area with a pool for fish.

Two debris jams were also removed from the brook, one of which had a natural digger log already in place. After the first debris jam was removed, the crew decided this log could be further developed because the back side of it had a deep hole. The log was then pinned with rebar and a few smaller logs were placed and pinned in front of it. The hole was then filled in with gravel and sand to prevent water from flowing below the log. The crew had also planted about 50 Willow tress along the length of the site location in hopes that they would help retain some of the water in the area.

Brook Profile

On July 12^th, 2024, the field crew constructed a brook profile on Bennery Brook using the YSI. Tests were taken above and below selected logs in the brook (BB1-BB7) and 1 ½ meters below where a pipe exits the nearby sewage treatment plant (BBS). The weather conditions that day were cloudy and there had been a heavy rainfall the night before. The crew began their tests at BBS which was the most downstream location and worked their way upstream to BB1.

Table 1: YSI data table for July 12^th, 2024

As presented above, the pH was higher at the first log, dropped between the fifth and seventh, the rose again after the sewage treatment plant. As for conductivity, the values seemed to decrease as measurements were taken further upstream. The crew suspected this was because the downstream portion of this profile lied directly adjacent to the road and receives more runoff than the upper portion would. The salinity values presented also indicate this trend.

Results

In total 208 meters of Bennery Brook was restored with pool depths raised about 3 inches above each digger log. The resulting pool depth about 3 meters above the first digger log was 30cm and directly below, 39 cm. The pool depth about 2 meters above the second log reached 16cm and directly below the log was 31 cm. Above the third log, the pool depth was 21cm and below was 34 cm. The crew had noticed that after the digger logs were placed, another king fisher was spotted in the area and more fish seemed to be making their way upstream.

Future Recommendations

It would be beneficial to place a few digger logs past where Sandy Cole Brook and Bennery Brook meet as this would further develop the pools in this area. There is also a large debris jam in this area that if removed, would increase both flow and fish passage to this area. The culvert that flows out of Sandy Cole Brook could also use a structure for beaver passage to prevent them from walking across the highway. This structure would also make the road safer for people on their daily commute as this year was not the first time a dead beaver was seen in the area according to locals.

A flat area downstream from the current digger logs would benefit from another digger log (44.91838° N, 63.53855° W). The placement of this log could be beneficial because although during low flow this area is dry, during high flow the log could push more water back to its original path, further dig out the existing pool, and hold more water in this area during the dry season.

The wetland adjacent to the site location would benefit from a more defined area for water passage. During the dry season this area remains dry except for a small pond and a small swamp. Defining a channel for water passage would promote water storage and keep the wetland charged. The area could also benefit from a few vernal pools being dug to further aid in water retention. Placing these structures could also prevent some flooding from reaching the farmer’s property.

The removal of blast rock from the brook to allow for more spawning beds in the brook could also promote an increase of life in the area. This rock could be used for bank stabilization or be used to create deflectors and ramps for digger logs.

References

Apple. (2024). Retrieved from Maps: https://beta.maps.apple.com

Government of Canada: Atlas. (2024). Retrieved from Toporama: https://atlas.gc.ca/toporama/en/index.html

McCallum Environmental Ltd. (2024). Wetland Vulnerability Study: Shubenacadie Watershed, Nova Scotia. Bedford, NS.