Catiline Creek Debris Flow Hazard

Introduction

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 following information has been compiled to provide the most up-to-date outline of the hazard, as at March 15, 2016.

To be advised when further updates are made, please opt-in to the SLRD Catiline Creek Debris Flow Hazard & Risk email group by clicking the link to the right. 

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 LUC 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

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. 

Next Steps

Regarding the conceptual mitigation options presented in the BGC Assessment, the SLRD is facilitating stakeholder negotiations to discuss the potential to implement mitigation works to reduce the geotechnical risks to a tolerable level and is approaching 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. 

Stay informed

People with questions may wish to contact the SLRD's Chief Administrative Officer Lynda Flynn at (604) 894-6371 ext. 231 or by email at lflynn@slrd.bc.ca.

This web page will be updated as more information becomes available. If you would like to be advised when updates are made, please opt-in to the SLRD Catiline Creek Debris Flow Hazard & Risk email group by clicking on the link to the right. 

Background documents

Services > Emergency Management > Local Hazard Warnings > Catiline Creek Debris Flow Hazard