Appendix 3 table details the numerous risk factors, evaluation parameters and decision criteria that are intended to support Ministry of Natural Resources and Forestry (MNRF) staff in their evaluation of risk for proposed water crossings. Appendix 3 does not assign priority to any individual or combination of risk factors, and it is not assumed that one or more of the evaluation parameters that are within “medium” or “high” risk decision criteria will necessarily shift a project into a similar risk assessment category.

Appendix 3 table should be used in conjunction with Department of Fisheries and Oceans (DFO) Pathways of Effects (PoE) diagrams to better understand the type of cause-effect relationships that are known to exist and the mechanisms by which stressors ultimately lead to effects in the aquatic environment.

MNRF reviewers should utilize the contents of appendix 3 table as a collection of considerations, together with local knowledge, site conditions and fishery management objectives that help to inform the development of appropriate avoidance and mitigation measures to reduce or eliminate the potential effects of proposed projects.

Table - risk factors, evaluation parameters and decision criteria for evaluating the risk of proposed water crossings to fish and fish habitat

Risk factor: fish presence

Evaluation parameters Low risk / decision criteria Medium risk / decision criteria High risk / decision criteria Information source Rationale
Channel type (permanent, intermittent, ephemeral) Intermittent ephemeral Permanent Permanent
  • Topographic maps
  • Aerial photographs
  • Forest resource inventory maps
 Permanent streams are accepted to support fish and thus have fish habitat associated with them.
Watershed area Very small watersheds, no significant water surface area Small watersheds Large watersheds; significant water surface area
  • Topographic maps
  • Aerial photographs
  • Forest resource inventory maps
 The probability of fish being present at a site is correlated with stream size. Watershed area and stream order are indicators of stream size. The threshold watershed size varies with the species, stream characteristics (slope, etc.) and geographic/physiographic area.
Watershed position (1:20,000) Stream order/ 1st order (unless flows directly to 3rd order or higher or known fish-bearing water) 2nd order (unless flows directly to 3rd order or higher or known fish-bearing water) 3rd order and greater
  • Topographic maps
  • Aerial photographs
  • Forest resource inventory maps
 N/A
Barriers that would prevent fish passage Physical - downstream Physical -downstream; passable only in some years None
  • Topographic maps
  • Aerial photographs
 Temporary natural (beaver dam) or man-made barriers should not be considered as indicators of the probability of fish being absent upstream.
Fish presence Confirmed absent from similar/nearby watersheds N/A Confirmed present in similar/nearby watersheds
  • Lake surveys
  • Research Investigations
  • Public reports
  • Direct observations
 N/A
Fish community sensitivity Generalist N/A Specialist
  • Lake surveys
  • Research Investigations
  • Public reports
  • Direct observations
  • Land Information Ontario (LIO)
 Scientific literature Decision support tools Generalist/specialist can refer to habitat requirements or life history depending on context, and varies with life stage, e.g. brook trout and walleye are specialists, and bass are generalists.
Species at Risk Absent Potentially present Present N/A
Habitat type: spawning, rearing, nursery, feeding, migration Marginal Important Critical
  • LIO
  • Aerial photographs
  • Surveys
  • Research
  • Direct observations
 Look at fish habitat at the proposed crossing site, downstream and upstream of the proposed crossing site.
Area impacted (total habitat impacted m2) Small streams; narrow flood plains; relatively short structures (low fills) N/A Large streams; causeways; long structures (high fill, wide road)
  • Aerial photographs
  • Direct observations
 Depending on the type of structure, the area impacted may be reduced. For example, portable bridges would generally impact a smaller area than culverts.
Productive capacity Bedrock/sand substrate, dystrophic waters, no cover N/A Aquatic macrophytes; silt/sand, cobble/ boulder substrate, instream or overhead cover
  • Aerial photographs
  • Soils maps
  • Direct observations
 N/A
Substrate (habitat sensitivity) Bedrock N/A Sand, gravel, cobble; groundwater discharge
  • Aerial photographs
  • Soils maps
  • Surficial geology
  • Maps
  • Direct observations
 N/A
Habitat supply High Medium Low
  • LIO
  • Aerial photographs
  • Surveys
  • Research
  • Direct observations
 If habitat is in low supply, any impacts to that habitat by construction of the crossing elevate the risk to fish that use that habitat.
Cumulative impact No other developments in area Water crossings in area Other developments in area or large numbers of crossings already in the watershed
  • LIO
  • Sustainable forest licensee maps of roads and water crossings
 This parameter relates to the density of development in the watershed.
Potential for fishery Low probability Possible Existing
  • MNRF files
  • Knowledge
 N/A

Risk factor: fish passage

Risk factor Evaluation parameters Low risk / decision criteria Medium risk / decision criteria High risk / decision criteria Information source Rationale
Structure installation Slope of channel at structure location <0.5% 0.5-2.0% >2.0%
  • Topographic maps
  • Digital terrain model
  • Aerial photographs
  • Decision support tools (OFAT
The risk associated with a specific slope varies with stream size and substrate characteristics. As slope increases, it is more likely that a culvert cannot be properly embedded due to coarser substrates. A culvert installed where the channel is sloped will have higher water velocity during high flows; low water depth during low flows and is less likely to have natural channel substrates inside the structure.
Structure installation Channel substrate Sand and gravel Cobble Boulders and bedrock
  • Direct observation
  • Aerial photographs
  • Surficial geology
  • Maps
 The risk associated with a specific slope varies with stream size and substrate characteristics. As slope increases, it is more likely that a culvert cannot be properly embedded due to coarser substrates. A culvert installed where the channel is sloped will have higher water velocity during high flows; low water depth during low flows and is less likely to have natural channel substrates inside the structure.
Structure sizing Design flow 25 year or greater 10 year 5 year Supplied by sustainable forest licensee Structures with lower design flows, or which constrict flows (prevent access to floodplain), will have higher water velocity
Structure sizing Structure width relative to channel or flood plain width >1.0% 0.5 – 1.0% <0.5%
  • Direct observation
  • Aerial photographs
 N/A
Structure sizing Changes to water velocity Little change or low velocities Some change or moderate velocities Substantial change or high velocities
  • Installation practices at crossing provided by sustainable forest licensee
  • Published literature on fish swimming abilities (DFO's SPOT tool
 High water velocities can act as barriers to fish passage. The influence of water velocity is different for each species.
Base flow depth Water depth in structure >20cm (depth adequate for most migrating fish, sturgeon may be an exception) 10 cm <5 cm
  • Digital terrain model
  • Topographic maps
 Beaver dams should not be considered barriers to fish movement because they are a natural influence on most watercourses. Beaver dams are generally temporary in nature. DFO's Interim code of practice: beaver dam removal should also be followed.
Fish present Barriers Other barrier to fish movement immediately downstream N/A No barriers
  • Aerial photographs
  • Direct observation
 N/A

Risk factor: erosion/sedimentation

Risk factor Evaluation parameters Low risk / decision criteria Medium risk / decision criteria High risk / decision criteria Information source Rationale
Erosion and sedimentation from on land activities Slope of approaches 1 – 4% 0-15% (0-8°) 5 – 8% 16-30% (9-17°) 9 – 12% 31-45% (18-24°) Extreme >12% > 46% (>25°)
  • Digital terrain model
  • Slopes provided by Regional Engineering Unit.
 Stream valley cross-section describes the slope of the approaches and potential for erosion.
Erosion and sedimentation from on land activities Length of approaches to top of bank 0 to 10 metres 10 to 50 metres > 50 metres Information supplied by sustainable forest licensee Approaches sloping to water crossings are sources of sediment through runoff which is exacerbated through improper grading.
Short-term sediment and direct impacts to fish Timing (species occurrence or thermal regime) Construction outside the timing window N/A Construction inside the timing window Information supplied by sustainable forest licensee N/A
Short-term sediment and direct impacts to fish Installation method Isolated from flowing water N/A In stream Information supplied by sustainable forest licensee N/A
Short-term sediment and direct impacts to fish Planning and practitioner proficiency All of listed items 1 or 2 of listed items None of listed items
  • Information supplied by sustainable forest licensee MNRF training records
  • Compliance records

Proficiency list:

  • sustainable forest licensee procedures
  • sound practical experience
  • water crossing Installation training
  • training in use of guidelines
Long-term (change to natural channel processes) Long-term (change to natural channel processes) C Soils on banks Bedrock, stony Loam, clay Sand, silt Surficial geology maps Type of soil influences erodibility
Long-term (change to natural channel processes) Long-term (change to natural channel processes) C Stream type (Rosgen 1996) Bedrock dominated, entrenched, step, pool Aa+, A, B, Meandering but not entrenched, stable banks, riffle/pool C, D, E Entrenched and actively meandering, unstable (braided channel) – relocate crossing F, G Rosgen, 1996 The influence of stream type must be considered within the context of channel slope (see Structure installation) and the type of structure proposed for installation at the site.
Long-term (change to natural channel processes) Long-term (change to natural channel processes) C Changes to water velocity Little change or low velocities Some change or moderate velocities Substantial change or high velocities Installation practices at crossing provided by sustainable forest licensee Changing the water velocity and alignment of the flow can cause downstream erosion.
Long-term (change to natural channel processes) Fill height 1 – 1.5 metres 1.6 -3.9 4.0 + metres Information supplied by sustainable forest licensee Higher fill heights mean there is greater surface area for water to impact, even if graded to a stable angle of repose. Stabilization of fill slopes would lower risk. Fill acts as a dam and the greater the fill height, the more head and risk of ‘piping’ through the fill.
Long-term (change to natural channel processes) Fill material Rock, cobble Pit run gravel Sand, silt, clay Information supplied by sustainable forest licensee N/A
Crossing failure Design flow 25 year or greater 10 year 5 year Information supplied by sustainable forest licensee The risk of catastrophic failure
Crossing failure Fill type Rock, pit run gravel Loam, clay Sand, silt Information supplied by sustainable forest licensee Fill type influences erodibility and hence the likelihood of failure.
Downstream fish habitat occurrence Downstream habitat type Marginal Important Critical
  • LIO
  • Aerial photographs
  • Surveys
  • Research
  • Direct observations
 If a chronic or catastrophic sedimentation event occurs, downstream habitat may be directly or indirectly impacted. Distance downstream at which an impact will occur is dependent upon flow, velocity and type of material being transported. Professional judgment is used to identify how far downstream habitat may be impacted.