Information from Watershed Watch’s Project Biologist, Tanis Gower, was used to create the prioritization criteria for this analysis, which included one constraint and three factors:
Constraint – Is the infrastructure already Fish-friendly?
Fish-Friendly infrastructure allows for the safe passage of fish to upstream habitat, through the opening of floodgates or passage by alternative means. This map shows the existing infrastructure, and whether it is currently Fish-Friendly or not.
It should be noted that though infrastructure is indicated as “Fish-Friendly”, it may not always be acting as such – some floodgates open daily while others open for less than 20% of the day, which results in substantially lower dissolved oxygen rates, and therefore unsuitable salmon habitat (Seifert and Moore, 2018). Since there was insufficient data to determine if the Fish-Friendly infrastructure was actually operating in a manner that maintained good salmon habitat, this was used as a constraint. If the infrastructure was deemed Fish-Friendly, it was excluded from being considered for priority upgrade, since there was a possibility that it already was sufficiently connecting waterways. Thus, all the non-Fish-Friendly infrastructure was then analyzed from the following factors:
Factor #1 – What is the cost of infrastructure upgrade?
Upgrading floodgates and pump stations have significantly different costs. Lina Azeez, the head of the Connected Waters campaign, estimates that upgraded floodgates would cost between $75 000 – $150 000, while pump stations are around $1.5 million.
Factor #2 – What is the length of potential salmon-bearing waterway upstream of the structure?
Based on an algorithm incorporating stream gradient, developed by Watershed Watch, and using the data of length of the upstream waterway, the length of potential salmon-bearing waterway was calculated. This data was presented in terms of being very high (>15km), high (15-5km), medium (5-1km), or low (<1km).
Factor #3 – Is there water quality data available?
Watershed Watch had collected water quality data for many of the waterways upstream of infrastructure sites, but not all of them. Having water quality data is important as it indicates what the current conditions are and whether more flow to the waterway would improve salmon habitat.
Other criteria
There are many more constraints and factors noted by Tanis Gower that should be considered for a truly comprehensive analysis and accurate list of priority upgrade sites, such as:
- Waterway has fish access during part of the year, but out-migrating native fish are killed by the current pump.
- Waterway has fish passage issues that would be improved with a floodgate(s) that opened more frequently.
- Waterway has an existing population of salmonids that would benefit from greater connectivity.
- Waterway has significant existing riparian shading (based on percentage of 10m riparian buffer that supports native trees and shrubs).
- If no to the above, waterway has significant potential for improving riparian shading, due to interested landowners and stewards.
- The current floodgate/pump is due for upgrades or is clearly outdated, and/or local government is interested in upgrading at this location.
- A stewardship community is actively interested in improving riparian shading and other measures of healthy fish habitat in this waterway.
- Local First Nations have an interest in improving connectivity and fish habitat in this waterway and/or have known cultural sites, known fishing sites or restoration projects in this waterway.
Therefore this analysis can only provide a very preliminary indication of which flood infrastructure sites may be prioritized for upgrade. In order to conduct a full analysis, there is a significant amount of data that would still need to be collected.