Fort Folly Habitat Recovery

Third Level Assessment – Aquatic and Riparian Habitat Assessment

Wildlife

Several species of wildlife that warrant specific attention due to being Species at Risk, have been documented historically in the Anagance watershed.  Atlantic salmon (Salmo salar) Inner Bay of Fundy (iBoF) populations were listed as endangered under the Species at Risk Act in 2003 (DFO, 2010; SARA Registry, 2013a), and the species is considered extirpated from the Petitcodiac River system, except for those introduced in stocking programs (AMEC, 2005). American eels (Anguilla rostrata) were designated as “Special Concern” by COSEWIC in 2006 (COSEWIC, 2006).  Their status was re-examined and raised to “Threatened” in May 2012 (COSEWIC, 2014). This species is being considered for listing under the federal Species at Risk Act, but currently it has no status (SARA Registry, 2013b).   Wood turtles (Glyptemys insculpta) were designated as “Special Concern” by COSEWIC in 1996 which was raised to “Threatened” in 2007 (COSEWIC 2007; COSEWIC 2011). This species is listed as “threatened” under the Species at Risk Act (SARA Registry, 2012).  Guidelines for projects in areas with these species are in Appendix A.

The decline in numbers of iBoF salmon is a marked contrast to the abundance described by early settlers (Dunfield 1991).  Though numbers of this species had been decreasing for some time (Elson 1962) construction of the Moncton to Riverview causeway in 1968 eliminated fish passage for adult salmon and smolts and effectively (but for ongoing intervention) extirpated the species from a river system that represented 20% of the total iBoF population (Locke, et al. 2003).  On the Anagance Atlantic salmon were observed historically wherever suitable substrate and shelter were found (Andrews 1943; Huntsman 1944; Huntsman 1945).

Unlike salmon, eels were not excluded by the Moncton to Riverview causeway downstream on the Petitcodiac.  In fact, while the causeway gates were closed eels were found to be the most abundant resident species upstream of the headpond (Flanagan 2001), and one of the dominant species within the headpond (Locke et al 2000). Within the Anagance, American eels have been documented in the past with some regularity (Andrews 1943; Godfrey 1951).

Considering the numbers of wood turtles encountered elsewhere in the Petitcodiac system there is no reason to think that they are not present in the Anagance watershed. However, a review of literature turned up no historical documentation of their presence or absence specific to the Anagance watershed.  This was not surprising as the Petitcodiac Watershed Alliance (Smith and Downey 2017) noted that their Wood Turtle research was the first formal study undertaken within the Petitcodiac Watershed. Prior to that, knowledge of wood turtles within the Petitcodiac was limited to anecdotal sightings.

The Anagance watershed has not been the subject of much recent field work by FFHR or other organizations.  It can be reasonably assumed based upon data from other parts of the Petitcodiac that: there are somewhere between very few and no salmon in the Anagance today; eels are comparatively common on the Anagance, and possibly increasing in numbers since the Petitcodiac causeway gates were opened (Redfield 2017); and that numbers of wood turtles on the Anagance are simply unknown.  Such knowledge deficits could be addressed by undertaking field work within the Anagance targeted to specifically address them.

Water Quality

Water quality on the Anagance River has been monitored by the Petitcodiac Watershed Alliance as part of their Petitcodiac basin wide water monitoring program, which has data going back to 1997 (Petitcodiac Watershed Alliance 2017).  The 2016 results are presented here (Petitcodiac Watershed Alliance 2016). They maintain a fixed monitoring site near the mouth of the river at the bridge on Mill Road in the Village of Petitcodiac. As a single site within the watershed there is a limited amount that can be concluded from it, however being located just above the point where Anagance meets the North and becomes the Petitcodiac, it does provide useful insights to the watershed upstream of it.  The fact this location has been monitored for years provides significant time depth.  Interestingly conductivity readings for the Anagance are more comparable to those on the Little and the Pollett, than to the North River. This is probably a reflection of the location of the sampling site along the North, a short distance upstream of the mouth of Salt Springs Brook.  While the data for the North is obviously not directly influenced by Salt Springs Brook itself, presumably there is related substrate in the area that contributes to the elevated conductivity readings.  That said, much of the same geological substrate (the Anagance Axis Salt Area (Hamilton 1961)) underlies the Anagance watershed so one might have expected some similar influence on Anagance surface waters as well, which appears not to be the case.

Table 2:  Water Quality on the Anagance in 2016 (Petitcodiac Watershed Alliance 2016)

Geomorphic Analysis

The following is taken from the report prepared by Matrix Solutions (Yates 2017) based upon the rapid geomorphic assessments (RGAs) and rapid site assessments (RSATs) that Fort Folly Habitat Recovery conducted in 2016.  The lowest 6.4 km of the Anagance were assessed. The survey started at the mouth of Hayward Brook, approximately midway between the Village of Anagance and the Village of Petitcodiac, and ran down to the confluence of the Anagance with the North River, where the two merge to become the Petitcodiac River.  The 20+ kilometres of river above this starting point were not included in this survey because the channel from that point on upstream is poorly defined, flowing through open marshy wetlands with high water temperatures, and of limited value to salmonids.  Similarly, neither Hayward Brook nor Holmes Brook were assessed, as the size of each was below the target threshold.  The focus here was on the portions of the main stem of the Anagance River where the channel could provide a meaningful contribution to salmon habitat.

Figure 8: Anagance watershed and assessed reaches (in red)

Geomorphic Background

Data collected from the Rapid Geomorphic Assessment (RGA) and Rapid Stream Assessment Technique (RSAT) were used to evaluate the geomorphic condition and stability of the assessed reaches of the Anagance River. In order to interpret the geomorphic data, the included maps of the watercourse are highlighted according to reach stability and dominant geomorphic processes.

Rapid Stream Assessment Technique (RSAT) – Methodology

The RSAT provides a qualitative assessment of the overall health and functions of a reach in order to provide a quick assessment of stream conditions and the identification of restoration needs on a watershed scale. This system integrates visual estimates of channel conditions and numerical scoring of stream parameters using six categories:

  • Channel Stability
  • Erosion and Deposition
  • Instream Habitat
  • Water Quality
  • Riparian Conditions
  • Biological Indicators

Once a parameter has been assigned a score, all scores are totaled to produce an overall channel health rating that is based on a 50 point scoring system, divided into three classes:

<20 Low

20-35 Moderate

>35 High

Rapid Stream Assessment Technique (RSAT) Results

Figure 9 outlines the RSAT classes of the reaches assessed in the Anagance River watershed. The vast majority of reaches were scored in the ‘high’ class range (71%). 29% of the assessed reaches scored a RSAT class within the ‘moderate’ class range. These high stability class reaches are characterized by well vegetated banks with excellent riparian conditions, good channel stability, a balance between scour and deposition, good instream habitat, and high water quality.  The substrate within the assessed reaches is composed primarily of cobbles and

Figure 9: Anagance River RSAT scores

gravels, with some occurrence of bedrock. The lowest scoring reach (reach 13) received an RSAT score of 21. This was lower than the other reach scores by a considerable margin. This reach was located in the middle portion of the assessed reaches where the channel enters an area identified as being an active horse pasture (Figure 10). The trampling of soil and grazing of vegetation along the top of banks minimizes the stability of the channel banks leading to excess erosion and sediment discharge.  In addition, the excessive organic input from horses likely contributes to poor water quality, minimizing the suitability for aquatic species. Lack of vegetation along the banks further reduces available habitat for aquatic species and contributes too increased water temperature levels.  The quality of the riparian conditions and the surrounding land-use appear to be negatively impacted in this reach which is expected to remain in poor condition unless improvements are made.

Figure 10: Reach 13 RSAT

Rapid Geomorphic Assessments (RGAs) – Methodology

The RGA is used to quantify channel stability based on the presence and (or) absence of key indicators of channel adjustment (Parish Geomorphic Ltd.  2003) with respect to four categories: 1) Aggradation, 2) Degradation, 3) Channel Widening, and 4) Planimetric Form Adjustment. Each indicator has been described in detail below.

Aggradation

Channel aggradation may occur when the sediment load to a river increases (due to natural processes or human activities) and it lacks the capacity to carry it. Piles of sediment in the river can re-direct flows against the banks, leading to erosion and channel widening.

Typical indicators used to identify aggradation include:

  • Shallow pool depths.
  • Abundant sediment deposition on point bars.
  • Extensive sediment deposition around obstructions, channel constrictions, at upstream ends of tight meander bends, and in the overbank zone.
  • Most of the channel bed is exposed during typical low flow periods.
  • High frequency of debris jams.
  • Coarse gravels, cobbles, and boulders may be embedded with sand/silt and fine gravel.
  • Soft, unconsolidated bed.
  • Mid-channel and lateral bars.

Degradation

Degradation occurs as the river cuts deeper into the land and decreases its gradient. This can occur from a rapid removal of streambed material due to an increase in discharge, water velocity, or a decrease in sediment supply. Bed lowering can move in both an upstream (as a headcut or nick point) and/or downstream direction. Indicators of degradation include:

  • Elevated tree roots.
  • Bank height increases as you move downstream.
  • Absence of depositional features such as bars.
  • Head cutting of the channel bed.
  • Cut face on bar forms.
  • Channel worn into undisturbed overburden/bedrock.

Widening

Widening typically follows or occurs in conjunction with aggradation or degradation. With aggradation, banks collapse when flows are forced on the outside, and the river starts to widen. Wide, shallow watercourses have a lower capacity to transport sediment and flows continue to concentrate towards the banks. Widening can also be seen with degradation, as it occurs with an increase in flows or decrease in sediment supply. Widening ultimately occurs because the stream bottom materials eventually become more resistant to erosion (harder to move) by the flowing waters than the materials in the stream banks.

Indicators of widening include:

  • Active undermining of bank vegetation on both sides of the channel, and many unstable bank overhangs that have little vegetation holding soils together.
  • Erosion on both right and left banks in riffle sections.
  • Recently exposed tree roots.
  • Fracture lines at the top of banks that appear as cracks parallel to the river, which is evidence of landslides and mass failures.
  • Deposition on mid-channel bars and shoals.
  • Urbanization and storm water outfalls leading to higher rate and duration of runoff and channel enlargement typically in small watersheds with >10% impervious surface.

Planform Adjustment

These are the changes that can be seen from the air when looking down at the river. The river’s pattern has changed. This can happen because of channel management activities (such as straightening the bends of the river with heavy equipment). Planform changes also occur during floods. When there is no streambank vegetation with roots to hold soil in place, rivers cut new channels in the weak part of the bank during high water. Planform adjustments typically are responses to aggradation, degradation, or widening geomorphic phases.

Indicators of Planform Adjustment include:

  • Flood chutes, which are longitudinal depressions where the stream has straightened and cut a more direct route usually across the inside of a meander bend.
  • Channel avulsions, where the stream has suddenly abandoned a previous channel.
  • Change or loss in bed form, sometimes resulting in a mix of plane bed and pool-riffle forms.
  • Island formation and/or multiple channels.
  • Additional large deposition and scour features in the channel length typically occupied by a single riffle/pool sequence (may result from the lateral extension of meanders).
  • Thalweg not lined up with planform. In meandering streams, the thalweg typically travels from the outside of a meander bend to the outside of the next meander bend.
  • During planform adjustments, the thalweg may not line up with this pattern.

Upon completion of the field inspection, indicators are tallied for each category to produce an overall reach stability index.  The index classified the channel in one of three stability classes:

Table 3: RGA reach stability index classification

Rapid Geomorphic Assessments (RGAs) Results

Figure 11 provides a map highlighting the RGA scores for the reaches assessed in the Anagance River watershed. The results of the RGA surveys indicate the majority of reaches are in a “Transitional or Stressed” state (59%). These reaches exhibit frequent evidence of instability and are moderately sensitive to altered sediment and flow regimes which will lead to instability. 29% of the reaches were identified as “In Adjustment” and 12% of reaches were found to be “In Regime”.  In adjustment indicates that those reaches are undergoing widespread instability that is outside of a natural rate of change.  The reaches found to be in adjustment were reaches 10 through 14 and are located approximately mid-way through the assessed length of river.

Figure 11: Anagance River RGA scores

Widening was identified as the most common primary geomorphic process (47%), with degradation being the second most common primary process (24%) within the Anagance River watershed. Aggradation and planform adjustment were also observed as primary geomorphic processes at 23 and 6 percent respectively (Figure 12). An alternating pattern of aggradation and degradation emerges with these processes either presenting as the primary condition or secondary underlying channel widening.

Figure 12: Anagance River Primary Geomorphic Processes

Channel degradation was most commonly associated with widening, particularly in the most unstable reaches. Degradation may occur when there has been a significant increase in flow, a significant decrease in sediment supply, or a significant increase in slope due to channel straightening.  In the middle reaches, degradation may be a result of increased flow provided by two incoming tributaries whose watersheds are heavily developed by roadways and cleared land. Land use conditions upstream of the assessed reaches (Figure 13) may also be contributing to the pattern of aggradation and degradation observed in the upper reaches.

Figure 13: Cleared land upstream of or adjacent to assessed reaches

Altered land use in the form of paved roadways or land cleared of mature vegetation does not hold runoff as well as vegetated or forested land.  This usually results in systems with high runoff, leading to higher peak flows and discharge over a relatively short period of time.  These systems are referred to as flashy watercourses.  Sediments may also be originating from these areas from improperly installed or maintained road crossings.  This issue is further compounded due to the condition of the underlying soils which are characterized as highly to very highly susceptible to erosion in this area of the watershed (Wall et al 2002; Fahmy et al 2010). Further investigation is required to pinpoint the source of sediments and cause of excessive degradation in the middle reaches.  The land identified in Figure 13 appears to be part of J.D. Irving’s Industrial Freehold (Figure 4) and the clearings are clear cuts. Historical imagery confirms this (Figure 14). Most of that harvesting is quite recent – part of the May 2015 image appears to freshly harvested, with additional cutting by April 2016.

Figure 14: Comparison between May 14th 2015 and April 29th 2016

 


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