Fourth Level Assessment – Aquatic Habitat Rehabilitation Plan
Summary of Issues Identified from Current Impacts
The 2016 Broken Brooks culvert survey by the Petitcodiac Watershed Alliance (Johnston et al. 2017) visited approximately 10% of the 71 water-crossings in the Anagance watershed, identifying one bridge and six culverts. Among these they noted two that allowed fish passage, three culverts that were partial barriers (due to debris and excessive outflow drops) and one that is a full barrier to fish passage (Figure 6). That small sample suggests that of the 65 remaining water-crossings identified during the GIS analysis, there are likely quite a few that may require remedial work of some kind.
The first step ought to be to complete the culvert survey of the watershed, to find and prioritize those crossings needing the most urgent attention. Plans for the 2017 field season to move on to the Memramcook River watershed, but presumably at some point as part of their ongoing culvert assessment program, the PWA will do the additional surveys on the Anagance to assess condition, identify barriers to fish passage, and where needed, undertake or recommend remediation options. That need is highlighted here, to keep it on the agenda for future work.
Summary of Issues Identified by Aquatic and Riparian Habitat Assessment
Though there is no recent data documenting the presence of threatened and endangered species (salmon, eels, and wood turtles) in the Anagance watershed, it is reasonable to assume that any of these could be present. Of the three, eels and wood turtles are both almost certainly present, while salmon are a strong enough possibility to warrant monitoring as part of any intervention. Consequently, projects must be planned and implemented with awareness of the vulnerabilities of these species. Fort Folly Habitat Recovery has developed project checklists (Appendix A) based on species biology to provide guidelines to help avoid or minimize the risk of negative impacts of projects on these species.
Analysis of the RGA and RSAT assessments (Yates 2017) conducted on the lower main stem of the Anagance River indicate that most of the reaches were determined to be in a transitional/stressed state while the remaining reaches were classified as in adjustment or in regime. One area in particular (reach 13) stood out as heavily impacted: RSAT (Figures 9 & 10) – moderate channel health; RGA (Figure 11) – in adjustment, with channel widening. Reach 13 stood out as the most heavily impacted site within the Anagance watershed, but not within the Petitcodiac overall. Sites in greater need of intervention exist on the Little River (low channel health). What is more, ongoing salmon stocking efforts on both the Pollett and the Little River elevate the immediate restoration priority of sites on those rivers compared to similar sites on the Anagance River.
In general, the RSAT/RGA results indicate that the Anagance watershed is responding to change with widening as the primary geomorphic process and degradation and aggradation as the secondary processes. Therefore, when restoration efforts are eventually undertaken, these should focus on establishing proper channel widths, ensuring connection to the floodplain and promoting sediment accumulation where applicable.
Reaches with excessive sediment accumulation may be restored via in-channel structures including rock vanes, upstream-V log weirs, double tree deflectors, and brush mattresses. These structures are designed to concentrate flows, promote scour pools, and narrow the channel. By narrowing the channel, the stream will regain the capacity to transport sediment as flow velocity will increase. In degrading sections of stream, rock toe structures and bank treatments can be used to establish proper channel dimensions. Structures highlighted above may also be used in degraded sections to encourage deposition in the proper areas and establish connection to the floodplain. This will encourage the channel to return to a state of dynamic equilibrium where sediment accumulation and deposition balance with flow discharge.
It is important that restoration structures be designed to fit the natural channel dimensions and hydraulic conditions of the site. Improperly placed or installed structures may do more harm than good. Logs used for structures should be freshly cut (dry logs will float, making installation difficult) and contain no rot. Recommended tree species are cedar, hemlock or spruce. If anchor stones are being used for log weir/log deflector support, the rocks should be angular rather than round as round rock fits poorly and tends to roll easily. A detailed site survey including longitudinal and cross-sectional profiles, pebble counts and riparian topography is necessary to appropriately identify a restoration strategy for a site.
At the watershed scale, best management practices should be promoted to improve the stability of the Anagance River. Although pasture land constitutes a low proportion of the watershed, the most degraded sections exist where agricultural land is concentrated along the riparian corridor. Many of the assessed reached of the Anagance River were identified as in adjustment and lack adequate riparian conditions due to surrounding land use. Shrub and tree planting will provide greater stability and habitat along banks that currently lack cover and will reduce sediment input. Active pasture along the channel should be restricted from access to the river to promote vegetation growth along the riparian corridor and to improve water quality. Any opportunities to reforest the riparian corridor will lower water temperatures, reduce sediment input, minimize non-point source pollution and improve channel stability.
Opportunities for Future Restoration Activities
Culverts and fish passage
The 2016 Broken Brooks Report (Johnston et al. 2017) identified three culverts in the Anagance watershed- C146, C147A, and C147B that are partial barriers to passage, and one that is a full barrier to passage – C148. The three partial barriers are all on Holmes Brook shortly before it reaches the main stem. Likewise, the full barrier is on Hayward Brook, shortly before it reaches the main stem of the Anagance. All four are so low in the system that they affect significant upstream habitat (9 to 10 km for the 3 partial barriers, and 3 km for the full barrier), likely to be of some value as they join the main stem within the portion deemed to be of sufficient value to salmonids to warrant Geomorphic Analysis. The remedial prescription for each of the three partial barriers is debris removal and construction of a rock weir. The report indicates that the full barrier likely will require replacement of the structure to restore passage (which is probably unlikely in the near term). Johnston et al (2017) indicate an intention to remediate the double culvert C147A &C147B if possible during the 2017 field season as part of their proposed work plan. The opportunity to do so however is subject to funding. The debris in question is a beaver dam, and as such it may be subject to reconstruction by the beavers, so that could become an ongoing issue.
Ideally one would complete the culvert survey of the watershed prior to undertaking remediation work, so that they can be ranked and prioritized within the context of those findings. It is unclear at the time of writing if the additional culvert surveys needed will be happening in 2017. However, the crew doing the culvert surveys is essentially the same crew that would be doing the remediation work. Thus it is likely that the remediation work will only go forward in 2017 if the culvert survey program is funded for 2017. If that does not occur, then the needs identified (additional surveys through out the remainder of the Anagance watershed; and specific culverts already noted as full or partial barriers and requiring attention) should be kept on the agenda as starting points for future work once funding is available.
Bank Restoration and Revegetation
Geomorphic Analysis (Yates 2017) identified several locations within the Anagance watershed where bank restoration and or revegetation efforts merit consideration. The first is a number of clear cut stands of Industrial Freehold (Figure 13), just above reaches 1,2, and 3, east of the Village of Anagance, with a single corporate landowner, J.D. Irving. The second is a horse pasture along reaches 12 and 13 (Figure 10), which according to Service New Brunswick is a single parcel of land, once again owned privately on both sides of the river by the same landowner. The fact that ownership of both sites is not complex could simplify future work at those sites, assuming of course that the owners of each are receptive to such engagement.
J.D. Irving property (Reaches 1,2, and 3)
Both along and adjacent to the main stem of the river, the network of sinuous ribbons of forest left behind after harvesting suggests that the required riparian buffer (spot checked in the images at approximately 60 m total, so 30 m on each bank) was left largely intact (Figure 15). The RSAT rating of moderate to high channel health for reaches 1, 2, and 3 is consistent with this. It was the RGA results that flagged the issue by detecting stress in reaches 1, 2, and 3 with aggradation as the primary geomorphic process in reach 1, and widening in both reach 2 and 3, and degradation in reach 4. These results are consistent with increased flow (Yates 2017), likely as a result of higher discharge rates from some sites clear cut as little as six months to a year (Figure 14) prior to the RGA field work. While the riparian buffers that were left helped mitigate the effects of this harvesting, the impact on the river was none-the-less detectable.
Figure 16: Estimation of approximate year of harvest based on historical imagery
Presumably the areas harvested between the buffers will return to forest over the next rotation, though these probably have been planted with J.D. Irving’s preferred commercial stock, rather than being allowed to regenerate naturally. The gradual return of forest cover as these sites regenerate, combined with intact riparian buffers, suggests that while the harvesting in this area has certainly had an impact the river, it need not be regarded as the highest priority within the Anagance watershed, which would instead be the horse pasture. After all, in the short term there is little additional work that could be done within the harvested stands or riparian buffers to improve the situation for reaches 1, 2, and 3 much beyond what has been done already.
Every year J.D. Irving plants thousands of acres of softwoods (primarily spruce species: white, Norway, and black, with some red) across its holdings (Lansky 2014). This process starts with clearcutting of natural forest (often mixedwood), followed by mechanical site preparation, planting, herbicides, precommercial thinning (at perhaps 20 years) and a short rotation- often harvesting at approximately 50 years.
In time these growing stands will offer much of the same absorption capacity as existed prior to harvesting. It is not as if the site has experienced conversion to a radically different land use, such as a hay field (common elsewhere within the Petitcodiac). The buffers are in place, and the sites have either started to regenerate, or more likely have already been sprayed and planted by now.
What would make a positive difference for the river in the future, is modifying the management decisions to be made as these growing stands near the end of their rotation. These will likely be managed as even-aged stands, to be clearcut once again. Based upon comparisons of historical imagery it appears as if most of this round of harvesting occurred quite recently in something like the order illustrated in Figure 16, noteworthy mostly for the short time frame over which these harvesting operations occurred. Due to the riparian buffers and the logistics required to navigate the roads and landings, it would have been relatively modular- done as distinct operational events. That being the case, if more time had been allowed to pass between the harvesting of adjacent areas, say 10 or so years, the cumulative effects on the watershed would have been reduced. That is because the residual absorptive capacity of this portion of the watershed would have been greater, making the river less subject to flash flooding. Given the observed modularity of the harvesting, the length of rotation, and the size of J.D. Irving’s Industrial Freehold land base in New Brunswick, it is likely that their operations could accommodate a program with a greater degree of spatially and temporally distributed harvesting, without prohibitive losses in efficiency. The history of J.D. Irving’s engagement with other similar initiatives within the Anagance watershed in the past (Chaisson 1996; Pugh 1999; Pomeroy 2002) suggests that they might be receptive to exploring the matter. Certainly,
Figure 16: Estimation of approximate year of harvest based on historical imagery
altering practices like that would appear to be the simplest way to further mitigate impacts of harvesting on the river while allowing future harvesting of even-aged stands of timber.
More ambitious efforts such as in-channel structures and bank treatments along reaches 1, 2, and 3 are also an option to directly address issues identified during the RGA process. The aggradation in reach 1 and widening in reaches 2 and 3 could be reduced using rock vanes to direct normal flows away from banks and create scour pools by constricting the channel and accelerating flows. Similarly, upstream-v log weirs direct flows away from the banks, narrow the stream channel, and can provide better access to the flood plain. Double tree deflectors could narrow the channel and concentrate flows near the centre to promote scour pools downstream of the structures. Brush mattresses along the banks could capture sediment during high flows and so help to narrow the channel. Bank treatments of engineered biodegradable fabric wraps can be secured in place with bank material (soil, gravel, cobble), and them planted with flood tolerant woody vegetation such as willow and dogwood- to help grade the floodplain and provide long-term bank stability. However, detailed site surveys including longitudinal and cross-sectional profiles, pebble counts and riparian topography are necessary to appropriately identify restoration strategies for such sites. These are not minor undertakings, and if executed poorly could make things worse rather than better. Given the overall high channel health of these reaches, and the lower priority of work in the Anagance (due to lack of salmon stocking efforts) they are not at the top of the list of sites to receive such intensive attention.
Horse Pasture (Reaches 12 and 13)
The RSAT result of moderate channel health, makes this site stand out as a priority for active intervention in the Anagance watershed (Figure 9). Though classified as moderate, the condition of reaches 12 and 13 is at the low end of that range, near to low channel health. This is a much more concerning state than reaches 1, 2, and 3 on the Irving property where channel health was classified as high. Like the Irving property, reaches 12 and 13 are owned by a single land owner on both banks, which simplifies the process if work is to be done. The RGA results (Figure 17) classify both reach 12 and 13 as in adjustment, which is the most sensitive category, and they are toward the extreme end of it, indicating that evidence of instability is widespread. The primary geomorphic processes in reach 12 is degradation, and in reach 13 is widening.
Figure 17: Compilation of RSAT and RGA results for Reach 13
Restoration efforts here should focus on establishing proper channel dimensions and, depending on the other associated geomorphic conditions, promote sediment deposition. In highly unstable areas such as this one, where degradation is occurring, ensuring proper channel connection to the floodplain and restoring riparian vegetation will aid in dissipating erosive forces during high flows. Restoration options such as the in-channel structures mentioned above and bank treatments to establish and maintain a stable channel, may be warranted.
Obviously contact with the landowner would need to be initiated to determine if such work is of interest to them. But even before that, one must consider how this site ranks as a priority within the Petitcodiac as a whole. The current capacity of FFHR has led to involvement in one such project a year for the last several years. The work flow has followed a “pipeline” pattern whereby: 1) a site has been identified and surveyed with plans being developed and funding sought; 2) the following year that plan has been implemented (while another is identified, plans developed, and funding sought); 3) then the third year monitoring has occurred on the first implemented project, the second project has been undertaken, and a third is then identified and prepared to be done the following year.
Given that capacity constraint of one actual implementation per year, sites must be prioritized across the Petitcodiac watershed as a whole. The salmon stocking and recovery work being done on the Little River and the Pollett River, causes sites on those rivers needing attention to outrank this one, as there are documented Species at Risk poised to immediately benefit. In 2016 the Mitton Farm pasture restoration was carried out in the headwaters of the Little River in September, followed by redd surveys that November which detected salmon redds just 100 or so metres downstream of that site (still on the Mitton property). These redds were the result of spawning ready adults being released into the Little River by FFHR downstream. There is no similar effort underway on the Anagance, making a site like this secondary to equivalent locations on the Little or Pollett Rivers where stocking efforts are ongoing. Thus, the question of whether or not this site warrants immediate intervention ought to be considered before even approaching the landowner. The answer is that it does not, given other priorities, and so it should be noted for future reference, rather than acted upon immediately. Approaching the landowner to enquire if they want help, but then not offering much assistance, risks alienating a contact who might otherwise be receptive. After all, the fact that activities on the Anagance are second in priority to the Pollett or the Little River is the reason why the Anagance was the fifth watershed for stewardship planning, rather than being among the first.
This is not to say that the landowner should not be approached at all. There is value in making contact and establishing a relationship. After all they may have resources and capacity of their own that can be encouraged and fostered by sharing information. The concern is to avoid the impression of offering more assistance than is likely to be forthcoming in the near term. If a decision is made to approach this landowner, it should be done with full recognition of the constraints imposed by the reality that the Anagance watershed is not a direct focus of ongoing salmon recovery efforts the way that other portions of the Petitcodiac are. While assistance with a project at some point in the future is certainly a possibility, such an opportunity is less likely to develop in the short term, than would be the case for similar sites within other parts of the Petitcodiac watershed. The RSAT/RGAs in the Anagance were conducted to identify and prioritize sites needing the most urgent attention within the Petitcodiac as a whole. Having added this site to that inventory provides context that strengthens the process by which project selections are made, even though Anagance projects don’t immediately top that list. This plan is a work in progress. It will be revisited in several years, by which time restoration work at reach 13 may rank higher than remaining sites elsewhere within the Petitcodiac.