Catiline Creek Debris Flow Hazard

Updated: March 12, 2025

Overview

The two communities of Lillooet Lake Estates and Heather Jean Properties are located in a geologically active area. Life safety concerns within the Catiline Creek drainage were highlighted by a debris flow on August 30, 2013. At the present time, the SLRD recommends that people not occupy dwellings, trailers or tents located within the purple or red zones identified by the Catiline Creek Debris Flow Hazard and Risk Assessment final report of January 22, 2015 ("the BGC Assessment"). 

Debris Flow Hazard and Risk Assessment 

Lillooet Lake Estates and Heather Jean Properties are both governed by a 1976 Land Use Contract (“LUC”) registered on title to the two legal parcels comprising the communities. The LU references a report prepared by Piteau Gadsby Macleod Limited dated April 2, 1976 (the “Piteau Report”), which considers geotechnical hazards related to residential development above the main forestry road. The Piteau Report includes a recommendation that no building development be carried out within an 800-foot wide corridor (400 feet of either side of Catiline Creek) until the completion of certain creek training measures. The SLRD has no record of any party undertaking those creek training measures. The Piteau Report also recommends that a permanent 300-foot wide corridor (150 feet on either side of Catiline Creek) be maintained where no permanent residential buildings would be allowed. Although the terms of reference for the Piteau Report applied only to the area above the forestry road, the Piteau Report notes that “the potential of flooding damage exists below the road as well” and that “it is advisable therefore to complete the corrective work on the creek to minimize the possibility of damage below the road”.

For many years, the SLRD has interpreted the LUC together with the Piteau Report as establishing:

  1. Creek Protection Corridor #1 (“CPC1”) - a 400 foot corridor (200 feet on either side of Catiline Creek) where only recreational uses are permitted and nothing is to be constructed so as to be permanently affixed to land; and
  2. Creek Protection Corridor #2 (“CPC2”) – an 800 foot corridor (400 feet on either side of Catiline Creek, as supported by the Piteau Report) where only common uses are permitted (i.e. no dwellings are permitted). 

Over the years, several geotechnical reports have identified hazards affecting the two communities. Most recently, life safety concerns on the Catiline Creek fan were highlighted by a debris-flow event on August 30, 2013. According to the geotechnical report immediately commissioned by the Ministry of Forests, Lands and Natural Resource Operations (the “MFLNRO Report”), the August 30, 2013 debris-flow event was the third of a similar size to occur since 2004 and saw an estimated 10,000 to 25,000 cubic metres of material deposited throughout a certain portion of the Catiline Creek fan.

Acting as agent of, and with emergency funding provided by, the provincial government, the SLRD retained an engineering firm to undertake remediation works in the wake of the event. The remediation works were not intended, nor designed, to eliminate the risk of future debris-flows.

After the August 30, 2013 debris-flow event, the provincial government confirmed that it would provide funding for the Catiline Creek Debris-Flow Hazard and Risk Assessment (the “Assessment”):

  • To quantify the geotechnical hazards and risks within the study area; and
  • To identify, in a very general sense, potential mitigation options (without detailed cost or design).

Although it provided the funding to undertake the Assessment, the provincial government did not commit to funding any potential hazard mitigation. At the regional government level, the SLRD is governed by a Board policy to not accept responsibility for natural hazard mitigation.

BGC Engineering Inc. (BGC) was retained by the SLRD, acting as agent of and with funding provided by the provincial government, to carry out the Assessment.  (“The BGC Assessment”)

Download the Final Report - Catiline Creek Debris-Flow Hazard and Risk Assessment - January 22, 2015 ("the BGC Assessment")

 

Download the Risk to Individuals Map

SLRD "Do Not Occupy" Recommendation

In April 2014, the SLRD Board issued a Do Not Occupy Recommendation to sites located within CPC1 and CPC2. This recommendation was based on the LUC, the Piteau Report recommendation that the corridors be maintained until specific creek training measures were completed, and the MFLNRO Report.

Following this recommendation, letters were hand delivered to all Lillooet Lake Estates and Heather Jean Properties sites and mailed to all Lillooet Lake Estates site owners for which the SLRD has contact information. Signs were also installed in two locations along the In-SHUCK-ch Forest Service Road on both sides of Catiline Creek to ensure that people entering Lillooet Lake Estates from either direction would be aware of the geotechnical hazards.

On January 22, 2015, BGC released its Assessment (the “BGC Assessment”). The BGC Assessment determined individual risk and group risk as well as identified newly updated risk zones within the study area.

The BGC Assessment identifies three quantified risk zones within the study area:

  • The Purple Zone sites are subject to a greater than 1:1,000 risk of fatality per year. This is the highest risk level within the study area, exceeding existing risk tolerance guidelines for existing developments as outlined in the BGC Assessment.
  • The Red Zone sites are subject to a greater than 1:10,000 risk of fatality per year. This is the next highest risk level within the study area, exceeding existing risk tolerance guidelines for existing developments as outlined in the BGC Assessment.
  • The Yellow Zone sites are subject to a greater than 1:100,000 risk of fatality per year. This risk level is tolerable, according to existing risk tolerance guidelines for existing developments as outlined in the BGC Assessment.

In March 2015, the SLRD Board re-affirmed the Do Not Occupy Recommendation and extended it to encompass the sites located within the Purple Zone and the Red Zone.  The SLRD Board also directed that updated signage along the In-SHUCK-ch Forest Service Road be installed to identify the Purple Zone and the Red Zone sites and to communicate the Do Not Occupy recommendation to members of the public and visitors.

Regarding the conceptual mitigation options presented in the BGC Assessment, the SLRD facilitated stakeholder negotiations to discuss the potential to implement mitigation works to reduce the geotechnical risks to a tolerable level and approached the provincial government, on behalf of residents, with the objective of achieving provincial participation in a collaborative approach to protect life safety within the study area.

  Debris Flow Mitigation Structure Project  

The Lillooet Lake Estates community selected one of the conceptual mitigation options in the BGC Assessment and engaged Kerr Wood Leidal to produce the Preliminary Design of Debris Flow Mitigation Works report in October 2016. This engineering report was funded by the LLE community, with a financial contribution being provided by the SLRD.

In September 2022, the Lillooet Lakes Estates community formally requested (via a petition process) that the SLRD:

  1. establish a new service area to tax requisition the Lillooet Lake Estates community for the costs of a Catiline Creek debris flow mitigation structure (the “Structure”) to mitigate risk to the community and
  2.  borrow up to $4 million dollars for the Structure. 

In December 2022, the SLRD Board adopted the Bylaws which finalized the service establishment and the associated loan authorization. 

The SLRD is leading the project to design, construct, and establish operation and maintenance of a debris flow mitigation structure for the Catiline Creek at Lillooet Lake Estates (the “Project”), based on the  preliminary design previously completed by Kerr Wood Leidal in October 2016. 

The objective of the Structure is to reduce the risk to the community and potential for loss of life by increasing capacity of the existing Catiline Creek channel to manage future debris flows of a capacity up to 100,000 m3 through the Lillooet Lake Estates community under a new forest service road bridge and into Lillooet Lake. 

The SLRD is to be the owner of the Structure and has responsibility for designing the Structure for the capacity noted above (i.e. up to 100,000 m3) and constructing, operating and maintaining the Structure. The Structure will be regulated under provincial legislation (the Dike Maintenance Act), and the SLRD will be the diking authority in respect of the Structure. 

As part of the detailed design phase of the Project, The SLRD’s consulting engineers will conduct an updated residual risk assessment with the proposed Structure in place and produce an updated residual risk assessment report and associated updated hazard map.  The design and reports will be reviewed by the Inspector of Dikes as part of the approvals process under the Dike Maintenance Act. 

Please see the project page for details and updates.

Land Use Contract Terminated and Replaced with Updated Zoning and Official Community Plan

In 2014, the provincial government amended the Local Government Act to terminate all land use contracts as of June 30, 2024. Local governments were required to have zoning bylaws in place by June 30, 2022 that would apply to the land once the land use contracts are terminated. As of June 2024 the LUC for Lillooet Lake Estates has now terminated and has been replaced with zoning for Lillooet Lake Estates and Heather Jean Properties as follows:  

Please see the project page for details and updates.

Under the existing regulatory regime the lands that encompass the Lillooet Lake Estates community are designated as a development permit area for the protection of development from the debris flow hazard associated with Catiline Creek.

As a result of this designation, the SLRD requires that a Natural Hazard Protection Development Permit be approved prior to issuance of a building permit. An application for a building permit must include a site-specific report from a qualified Professional Engineer or Professional Geoscientist (with expertise in creek hazards) that identifies potential risk from debris flow hazards and proposed risk reduction measures if required for safe use. For more information about the Natural Hazard Protection Development Permit, please refer to section 19.31 of the Electoral Area C Official Community Plan Bylaw No. 689, 1999 as amended on the SLRD’s website. 

Please note that additional Development Permit Areas may also be in effect, such as Riparian Assessment and Wildfire Protection Areas. You can contact the SLRD’s Planning and Development Services Department planning@slrd.bc.ca  for more information about the development permit process.

Post Mitigation Options for the Do Not Occupy Recommendation 

When construction of the Structure is completed, the SLRD’s consulting engineers will review the constructed condition of the Structure to determine that it is consistent with the design and updated residual risk assessment report. Post-construction of debris flow mitigation works, staff intend to take the updated geotechnical information to the SLRD Board and, depending on the details of the updated geotechnical information and subject to any other geotechnical issues that could arise in the interim, make recommendations to the Board in respect of the following matters:

  • the existing Do Not Occupy Recommendation; and
  • the existing debris flow Hazard Development Permit area designation.

Status of Existing Notice on Title Registered against Title

Due to there being existing Building Bylaw infractions on some Lillooet Lake Estates sites (such as “construction contrary to building bylaw regulations”), in 2013 the SLRD Board approved the registration of a Notice of Title against title to the lands (i.e. there are two parent parcels) that comprise the Lillooet Lake Estates community.  Please note that the existing Notice on Title is expected to remain registered against title to the lands that comprise the Lillooet Lake Estates community for as long as Building Bylaw infractions remain in respect of the relevant parent parcel.

Stay Informed

People with questions may wish to contact the Strategic Services Department.

This web page will be updated as more information becomes available.

Background Documents & Links