3 Structure Prioritization

Lateral Barriers (Including to thermal refugia)

There is a lack of comprehensive data and mapping of lateral barriers and potential thermal refugia in the watershed to currently support a strategic prioritization (see Table 1). However, local knowledge was used to compile a list of candidate sites for field verification as a starting point to improve lateral and thermal connectivity. These sites were investigated in 2021 (Mozin (2021)), but an atmospheric river event later that winter resulted in major modifications and rearrangement of the Coldwater River and mainstem Nicola River downstream of the Coldwater confluence, rendering the outcome of those investigations no longer relevant. Further assessment of off-channel thermal refugia was undertaken by Nooaitch Band in 2023, with results of those assessments expected to be released to the broader community working on conservation in the Lower Nicola Watershed in the near future.

Longitudinal Field Assessment Ranking Process

A primary outcome of the WCRP will be the rehabilitation of barriers to connectivity in the Lower Nicola River Watershed. To achieve the goals in this plan, it is necessary to identify a set of structures that, if rehabilitated, will provide access to a minimum of 52.38 km of rearing habitat (Table 3.1):

Table 3.1: Rearing habitat connectivity gain requirements to meet WCRP goals in the Lower Nicola River watershed. The measures of currently accessible and total habitat values are derived from the intrinsic potential habitat model described in Connectivity Status.

Habitat Type	Currently accessible (km)	Total	Current Connectivity Status	Goal	Gain required (km)
Rearing	394.19	465.18	85%	90%	52.38

After all existing data and knowledge are collated for known and modelled crossings, an iterative ranking process is conducted to identify barriers for rehabilitation to meet the WCRP goals. The ranking process is primarily used to guide field assessments and maximize efficiency in ground truthing data inputs and model outputs, while providing a secondary purpose to evaluate the relative key habitat gains of confirmed barriers in the watershed. This process, combined with input from local knowledge holders and experts, is used to develop field plans for assessing structures that have the potential to block the most key habitat in the watershed. Field assessments are based on the BC Fish Passage Strategic Approach and can include a barrier assessment (i.e., evaluating passability of the structure), a habitat confirmation (i.e., evaluation of whether the upstream habitat is suitable for the focal species and whether there are other undocumented human-made or natural barriers upstream or downstream), or a detailed habitat investigation (e.g., a fish passage study or further in-depth analysis of habitat features in a waterbody).

The ranking process accounts for the long-term and immediate habitat gains potentially offered by each structure to improve key habitat connectivity in the watershed. All structures in the watershed (excluding those confirmed as passable) are ranked in each iteration of the ranking process. Details of the ranking process used to guide field assessments can be found in Appendix B.

Longitudinal Structure Prioritization Summary

Following field assessments, structures are placed on one of five possible lists:

1. Priority barriers list – the structure is confirmed as a full or partial barrier, has key habitat confirmed to exist upstream, and is considered actionable by the planning team (i.e., action items will be identified to advance rehabilitation of the structure). Depending on the barrier, owner, financial constraints, and quality of upstream habitat, the action may be to leave to end of life cycle before reviewing again, remove and decommission the structure, replace with a new passable structure, or modify to temporarily restore connectivity (e.g., fish ladder or baffles installed; see Table 3.2).

2. Assessed structures that remain data deficient list – some form of field assessment has been completed on the structure, but further investigation is required to confirm either the passability status or presence/suitability of upstream habitat (see Table 3.3).

3. Rehabilitated barriers list – priority barriers that have been addressed either through removal, replacement, or temporary fish passage improvement projects; (see Table 3.4)

4. Non-actionable barriers list – the structure is confirmed to be a barrier to fish passage and has some amount/quality of habitat upstream, but the planning team will not identify actions to advance rehabilitation of the structure because of logistic considerations (e.g., financial costs), short habitat gain, or the upstream habitat is of poor quality or unsuitable in its present condition to support key life stages of the focal species Appendix C.

5. Excluded structures list – the structure is excluded from further consideration in subsequent ranking and work planning because the structure is confirmed passable (e.g., bridge), not present, or there is no key habitat upstream Appendix C.

Table 3.2:

Confirmed barriers

Barrier Id	Modelled Crossing Id	Watercourse Name	Road Name	Structure Type	Partial Passability	Structure Owner	Num Barriers Set	Total Hab Gain Set	Upstream Habitat Quality	Estimated Cost $	Next Steps	Reason	Notes	Supporting Links
196969	11304548	Murray Lake Creek	Maka-Murray/Maka-Michael JCT	Stream crossing - CBS		FLNRO	1	2.87		150000	Post-rehabilitation monitoring	Active Coho spawning and rearing stream	Culvert and road are a significant sediment source to stream
197882		Stumbles Creek	Unnamed	Stream crossing - CBS	Yes	Private	3	2.25	High	150000	Engage with partners	Important migratory corridor for Coho. Fully passable to adults, passable to juveniles at low flows and 50% at higher fllows.	Major habitat restoration potential at this site.	http://a100.gov.bc.ca/pub/pscismap/imageViewer.do?assessmentId=200141
197884	11300751	Stumbles creek	Highway 8	Stream crossing - CBS	Yes	MOTI	3	2.25	High	650000	Engage with barrier owner	Important migratory corridor for Coho	Passable to adult fish at all flows. No outlet pool and 0.11 m drop onto rocks likely an impediment to both juveniles and adults. The calculated water velocity is 0.07 m/s. CO fry captured. Water is diverted upstream of Hwy 8 for irrigation purposes during the growing season and regulated by a manual irrigation gate. Most water was diverted during the assessment. Mr. Miller observed CO spawning upstream of Hwy 8 after the gate was opened in the fall.	http://a100.gov.bc.ca/pub/pscismap/imageViewer.do?assessmentId=200143
1024713603		Skuhun Creek	mouth	Other	No	n/a			High		Post-rehabilitation monitoring	Mouth of river was perched above Nicola River following 2021 Atmospheric River, preventing fish from accessing.	Nicola River redirected and built up to eliminate elevation difference between the two streams.

Table 3.3:

Assessed structures that remain data deficient

Barrier Id	Modelled Crossing Id	Watercourse Name	Road Name	Structure Type	Structure Owner	Barrier Status	Partial Passability	Assessment Type Completed	Total Hab Gain Set	Num Barriers Set	Next Steps	Notes	Supporting Links
197692	11305296	Manning Creek	Manning Creek FSR	Stream crossing - CBS	FLNRO	BARRIER		Barrier assessment			Habitat confirmation (data deficient structures only)	Steep channel upstream of crossing.
197693	11303684	Manning Creek	Unnamed	Stream crossing - CBS	Private	BARRIER		Barrier assessment			Habitat confirmation (data deficient structures only)

Table 3.4:

Rehabilitated Structures

Barrier Id	Modelled Crossing Id	Watercourse Name	Road Name	Type Of Rehabilitation	Rehabilitated By	Rehabilitated Date	Total Hab Gain Set	Actual Project Cost $	Next Steps	Notes	Supporting Links
36b0bcda-4671-45ff-8dea-d1fc8abe3a8d		Clapperton Creek	n/a	Removal/decommissioned	CWF & LNIB	2024-08-01	15.59	332000	Post-rehabilitation monitoring	Important steelhead, Chinook, Coho stream
197889	24713603	Skuhun Creek	Highway 8	Retrofit	MOTI	2024-07-31	13.95		Post-rehabilitation monitoring	Clearspan bridge with concrete apron became perched. Stream bottom built back up through crossing and backwatered.

Mozin, P. 2021. Fish Passage Barrier Assessments and Habitat Confirmations at Stream Crossings in the Lower Nicola River Watershed. https://cwffcf.sharepoint.com/sites/Conservation-General/Shared: Scw’exmx Tribal Council.