Allan Water Improvement Project
Brash Bank Protection
Over the past couple of months I have been working with Sylvian to organise and carry out brash bank protection work on a 35m stretch of eroded bank at Mid-Cambushinnie Farm on the Allan Water that was causing the landowner concern. The bank is located in the mid-section of the Allan Water, which has a lot of issues with bank erosion as a result of historic dredging, and according to some, the removal of a natural rocky pinch point at Kinbuck Bridge to lower the water table for agricultural improvements during the war. Unfortunately, as a result of man’s alterations the Allan Water sits lower in the channel than it naturally should be, resulting in high eroding banks, disappearing fences and lots of fine silty sediment going into the river.
Brash bank protection is a relatively novel approach to stabilising banks and it was definitely a learning curve for the Trust, as this was the first time we had attempted to carry out such work. We received advice and recommendations from the Wild Trout Trust on what was required to stabilise the bank and also provide refuge habitat for fish in the process. The work involved using posts hammered into the toe of the bank in the river with living willow weaved around these posts. Then an additional line of posts was put part the way up the bank with the gap in between the posts being packed tightly with brash. After this was done fence wire was attached between the two sets of posts that are in the river (bank toe) and higher up on the bank to hold the brash in place. The idea is that the brash should dissipate the erosive force of the water before reaching the bank as opposed to deflecting the erosive force to the opposite bank resulting in erosion elsewhere. I was particularly keen to see if this would be a low-cost alternative to dumping rock onto river banks to control erosion, which unfortunately is a common low-cost approach adopted by landowners the length and breadth of the country.
Sylvian and I were able to obtain brash and willows locally from Noble Nordmann Forestry and a local farmer, and we organised our call to arms for volunteers for the 27th
of May to help us achieve the brash bank protection work at this site.
Thankfully, over the course of the two days we had 14 local volunteers plus Trust staff there to carry out and complete the work. The volunteers on both days and were fantastic and smiled and laughed throughout no matter what brash related challenge they came across. In addition, representatives of the Allan Water Angling & Improvement Association, the River Avon Federation, Slamannan Angling Protective Association, Linlithgow Angling Club, and East Lothian Angling Association were also present to learn, as we were, from the experience.
As we finished the work on day 2, the fly life became more noticeable, including a large Ephemera danica also known as the Green Drake. As a result, so did the number of trout rising in the pool beside us, which as you can imagine kept the fishermen present distracted!
Over the coming weeks I will sow the bare bank face with grass seed and fence off the top of the bank to exclude cattle from the site to finish the job and help the river bank’s recovery. It will be really exciting to watch and monitor how this piece of work develops to reduce bank erosion for the farmer, but also improve biodiversity and fish habitat in what is quite a bare and fine sediment rich section of the Allan Water. However, the true test is yet to come and hopefully it can withstand the Winter’s floods. Many thanks again to all who were involved, particularly the volunteers.
Tackling small barriers - opportunities on the Allan Water
The Allan Water Barrier Easement Project Phase 1 study, which looked at the passability and potential solutions to barriers to fish passage in the catchment was completed at the end of February by Royal Haskoning and funded by SEPA’s Water Environment Fund. Since then, I have been taking forward the findings from the report to deliver fish passage easement on structures highlighted, which will allow fish species to access the natural range of their habitat in the catchment that they are currently unable to access, or have limited opportunity in reaching.
The majority of the work has been the initial engagement with structure owners from private individuals to Transport Scotland to get the ball rolling and start dialogue. However, despite what may sound like the start of a long painful process, there has been gains for fish passage improvements already. One of the barriers is getting a technical fish pass put in and funded by its owner Tullibardine Distillery; one barrier owner is in communication with SEPA about improving fish passage to their structure; and another barrier has vanished in a flood event. Therefore two of the barriers from the study are in the process of, or have been addressed already, and hopefully it will not be long before a third one joins them. The latter barrier located on the Buttergask Burn that vanished is possibly the most interesting to talk about just now.
The Buttergask Burn structure was contributing to the waterbody’s ecological status of bad due to it being deemed impassable to fish. This designation is given by SEPA as part of their commitments to achieve good ecological status for all its waterbodies by 2027 to meet the Water Framework Directive target. As a result of this, structures like the Buttergask Burn are deemed a priority to address if they want to achieve this target. The barrier however looked more like a thick collection of woody debris. However, there was hard standing concrete at the downstream base of the structure and it was suspected there may be something engineered in there also to justify SEPA’s classification of the structure as important.
During the Allan Water barrier study that took place over the winter however a bypass channel had formed around the structure. This was great news, as this meant with a simple amount of management, which would cost little in comparison to environmental contractors, nature had made the structure passable to fish.
Following suggestions in the Barrier study report when it was complete, I obtained agreement from the landowner to fence off the area around the structure, including the bypass channel with a local fencing contractor to secure fish passage at the site. The Buttergask Burn at this location suffered heavily from cattle poaching and as a result there was a risk that the cattle may reduce the fish passability by destroying the passable channel when walking through it. Therefore we organised a date for the beginning of June to fence it off.
However, when the day came to fence the structure, I discovered that there was no structure left. The structure had been washed away resulting in the flow going down the main channel and leaving a de-watered bypass. This was very fortuitous as the main channel now is far easier for fish to pass,and the habitat in the burn has improved greatly with some fine sediments being washed away to expose gravels. Because of the damage done by cattle to the bank we decided to fence off the area anyway to reducing diffuse and source pollution from cattle going into the burn. The effects of the cattle poaching diminishing the quality of habitat in the burn were clearly visible still with lots of fine sediment and even cow pats present in the slack water.
Now the site is fenced off from cattle It will be interesting to monitor how this site reacts over the coming months, and hopefully improvements to the A9 road culvert downstream in the future, which also has fish passability issues, will allow for salmon and sea trout to return to their natural habitat range upstream of the A9 in the Buttergask Burn once again. We will electrofish the site later this summer, so if salmon did not get up the A9 culvert below during this wet winter, then it is a good indication that fish passability improvement works should be a priority for SEPA on this structure also.
The Trossachs Water Vole Project
The project’s annual programme of water vole surveys is well underway and there have been several successes already. Water vole presence has been confirmed in lots of sites including several which were newly discovered last year. This gives us hope that these outlying populations will be able to persist for years to come and produce young that will continue to disperse further into the landscape.
We have also discovered our first new colony of the season just to the South of Loch Venachar. This population represents the furthest known expansion of water voles to the North-East of the Loch Ard Forest re-introduction area and is a whopping 8km away from the nearest release site. An expansion of 8km in less than 8 years is really good going and shows just how well water voles can do when given a chance.
One survey did turn up some less good news with American Mink prints being recorded on a river bank right in the middle of an area which we think was only recently colonised by water voles. Fresh sign of water voles was also present so it seems that they have managed to survive the invasion for the moment and we are making every effort to trap the mink. This example demonstrates the need to keep extending and improving the mink control efforts in the area so that water voles have the best chance possible to reach new areas and create stable populations for the future.
The project relies on the voluntary effort of local individuals and organisations. If you think you might be interested in getting involved then please contact TWVP Project Officer Ryan Greenwood at:
Forth Invasive Non-Native Species Programme
We have moved on to the next phase of the Forth Invasive Non-Native Species Project (FINNS) thanks to grants from SNH, SEPA, FET and LLTNP. These funders have provided us with another years funding to continue the works around the Forth District tackling the invasive species in and around our rivers.
We have started the season off with battling the Giant Hogweed spraying up on the Allan water and around the River Almond. The Allan Water catchment is one the Districts most heavily infested areas for giant hogweed from Greenloaning down to the Firth of Forth. This stretch of river has been treated by the Trust and several dedicated volunteers who handle patches within Dunblane and Bridge of Allan. Treatment along the river has been successful thus far in the season.
Treatment along the River Almond has been concentrated on the Gogar Burn and the main stretch of the Almond along the lower reaches. These stretches are incredibly dense with GH even after several years of treatment. This is due to the heavy infestation and reintroduction from the roads and railway lines in this section. Keeping on top of this patch has been a priority of the FINNS programme as these sections are among populated areas and along public footpaths and cycle ways.
We would like to thank the volunteers who have managed to contribute some time to both the Allan Water and the Almond Catchment so far this year. As always we appreciate all the hard work and effort that our volunteers put in to the FINNS programme and we are always looking for more help. For information on volunteer opportunities within the FINNS programme you can contact Amy at email@example.com