There is a high economic risk attached to some of the creeks that traverse the city’s neighbourhoods, including one tributary that contains a high life safety risk, according to a recent engineering report.
In the Steep Creek Hazard Assessment Report by BCG Engineering out of Vancouver it was found that Cottonwood Creek — with Gold, Selous and Giveout creeks adding to its flows — had the potential for significant economic risk inside the city’s boundaries.
“Given the level of development on the Cottonwood Creek fan we’ve categorized it as high economic risk and do recommend that a detailed hazard and risk assessment be completed in the future, and that that assessment include these tributary creeks for a comprehensive study,” said BCG’s Lauren Hutchinson in her report Jan. 17 to city council on the matter.
The summary assessed four major creeks that affect city residents, with some consideration to creeks such as Giveout — which is susceptible to debris flows with a higher sediment concentration and higher potential forces in places that are developed — that ultimately influence the creeks running through Nelson.
In the Giveout Creek basin there are largely mobile and manufactured homes that are less resilient to impact than a wood-frame or concrete foundation structure, said Hutchinson.
“We’ve identified that there is high life safety risk on Giveout Creek,” she said.
The threat has been communicated to the regional district since the creek lies wholly outside of the city boundary.
The goal of the summary was to update the hazard boundaries in the city and also to prioritize the needs for steep creek hazards in support of planning and decision making.
This was the first step in reducing the city’s risks via steep creeks by taking a proactive approach in protecting residents and infrastructure and enhancing community resilience.
In the study BCG looked at creeks running through Nelson with grades more than five per cent (three degrees).
Steep creek hazards such as floods, debris flows and debris floods pose considerable risks to the city and can impact pedestrians, vehicular traffic and residents, particularly during periods of heavy rainfall or snowmelt.
These hazards can also pose a risk to development and infrastructure, as erosion and debris accumulation can cause damage to roads, buildings, and other structures.
The assessment identified that the creeks located within city limits did not pose a life safety risk, however, they do pose an economic risk. BGC Engineering ranked the creeks for further study in the order of priority as: Anderson/Fell Creek; Cottonwood Creek; Smelter Creek; Ward Creek.
“The Steep Creek Assessment report is the first phase of a multi-year project that will result in an increased understanding of local hazards and potential infrastructure upgrades,” noted a cit staff report to council.
The next phase of the project will be to obtain detailed steep creek hazard reports for each creek to identify and mitigate risks to residents, development, and infrastructure.
Many sources of funding will have to be sought for projects related to mitigation on the creeks, the BCG summary suggested.
Currently, grant funding is being sought to complete detailed hazard mapping and policy development for steep creeks as part of efforts to reduce the risks and impacts of natural disasters and extreme weather events.
Council has pledged support for applying for detailed hazard mapping for Anderson/Fell Creek through the UBCM Community Emergency Preparedness Fund (CEPF), a program that provides financial assistance to local governments in B.C. to help improve emergency preparedness and response capabilities.
The DRR-CA funding stream can contribute 100 per cent of the cost of eligible activities to a maximum of $150,000 per category.
• The Steep Creek Assessment Report can be found here.