High Level Description and Evaluation of Three Post 2024 Duncan Dam and Reservoir Operation Scenarios and A Constant Mid-Elevation Pool Scenario for the Arrow Reservoir

Author: A. Thomson

The information contained in the report was presented at the Columbia River Treaty (CRT) Sounding Board meeting held in Cranbrook July 5th 2013 and elaborates on material presented at the Fauquier CRT public meeting on June 15th 2013. The letter report is a brief and high level analysis that outlines the various scenarios described herein. Many of the outcomes suggested due to possible operational changes of the Arrow and Duncan reservoirs are based upon professional opinion, and numerous BC Hydro, Provincial and consultants' reports.

Summary of Evaluation of Duncan Dam and Reservoir Scenarios

– Many of the pre-dam environmental values and function lost due to dam construction and reservoir operation may return upon dam decommissioning and restoration of the upper and lower Duncan Rivers. However, benefits associated with current flood control and enhanced power generation in Canada would be lost and any Canadian Entitlement associated with the facility would be forfeited.
– Decommissioning the dam, restoring the upper Duncan River watershed, and addressing impacted infrastructure could cost $70M-$100M with the final cost likely being higher.
– Installing power generation at the Duncan Dam has been studied by both BC Hydro and Columbia Power Corporation. The latter estimates that between 20-30 MW of capacity could be installed in the low level outlet areas and produce 80-120 GWhrs per year from January-June. Capital cost would be in the $125M-$175M range. The idea is in the conceptual phase with no commitment from either corporation to proceed to further developmental phases.
– Installing hydro generation at the Duncan Dam would not significantly change operational environmental impacts on upstream and downstream resources.

Summary of Evaluation of Arrow Lake Reservoir Mid-Pool Elevation Scenario

A constant mid-pool elevation scenario for the Arrow Lakes Reservoir has numerous attributes that make it attractive in this high level scoping evaluation. Detailed analysis may reveal different outcomes.
– Some flood containment abilities of Arrow Reservoir will remain although in a reduced capacity as compared to current operations. A more detailed study would be needed to understand the flood risk to downstream Canadian communities.
– A constant mid-pool elevation scenario may resolve and address many environmental concerns that the Columbia River Water Use Plan identified at Arrow Reservoir, which various compensation and mitigation programs are targeted to address.
– From a social perspective, operating the reservoir to closely mimic pre-dam water fluctuation conditions (but not the original water elevation in the Arrow Lakes) may address some of the issues that concern local citizens – i.e. return of some inundated land to other uses over time (potentially food production, grazing, etc.), safer navigation, ecological values – and may address some of the residual anger and mistrust that some community members hold.
– The stable mid-pool scenario will have some positive and some negative effects on recreation and will affect the various communities differently. It is unclear how all recreational interests will perceive the changes.
– If the Treaty is terminated as is possible under this scenario there will be no Canadian Entitlement. It is unknown whether a Treaty scenario that removes all or part of the 7 Million acre-feet of storage at Arrow from the current 15 Million acre-feet of coordinated storage under the Treaty would be of interest to the U.S., or if valuation of other US interests such as navigation, recreation, irrigation and ecosystem function that Canadian Treaty Dam operations facilitate could partially (or fully) replace the Canadian Entitlement potentially lost due to reduced power generation in US plants.
– Decommissioning the HLK dam and ALG Station and restoring the Arrow Lakes reservoir to near pre-dam conditions would be unprecedented in scope and cost well in excess of $250M. Dam decommissioning or removal would not be necessary in order to address some of the total environmental or social concerns associated the facility and reservoir operation.

Summary of Evaluation of Duncan Dam and Reservoir Scenarios

– Many of the pre-dam environmental values and function lost due to dam construction and reservoir operation may return upon dam decommissioning and restoration of the upper and lower Duncan Rivers. However, benefits associated with current flood control and enhanced power generation in Canada would be lost and any Canadian Entitlement associated with the facility would be forfeited.
– Decommissioning the dam, restoring the upper Duncan River watershed, and addressing impacted infrastructure could cost $70M-$100M with the final cost likely being higher.
– Installing power generation at the Duncan Dam has been studied by both BC Hydro and Columbia Power Corporation. The latter estimates that between 20-30 MW of capacity could be installed in the low level outlet areas and produce 80-120 GWhrs per year from January-June. Capital cost would be in the $125M-$175M range. The idea is in the conceptual phase with no commitment from either corporation to proceed to further developmental phases.
– Installing hydro generation at the Duncan Dam would not significantly change operational environmental impacts on upstream and downstream resources.

Summary of Evaluation of Arrow Lake Reservoir Mid-Pool Elevation Scenario

A constant mid-pool elevation scenario for the Arrow Lakes Reservoir has numerous attributes that make it attractive in this high level scoping evaluation. Detailed analysis may reveal different outcomes.
– Some flood containment abilities of Arrow Reservoir will remain although in a reduced capacity as compared to current operations. A more detailed study would be needed to understand the flood risk to downstream Canadian communities.
– A constant mid-pool elevation scenario may resolve and address many environmental concerns that the Columbia River Water Use Plan identified at Arrow Reservoir, which various compensation and mitigation programs are targeted to address.
– From a social perspective, operating the reservoir to closely mimic pre-dam water fluctuation conditions (but not the original water elevation in the Arrow Lakes) may address some of the issues that concern local citizens – i.e. return of some inundated land to other uses over time (potentially food production, grazing, etc.), safer navigation, ecological values – and may address some of the residual anger and mistrust that some community members hold.
– The stable mid-pool scenario will have some positive and some negative effects on recreation and will affect the various communities differently. It is unclear how all recreational interests will perceive the changes.
– If the Treaty is terminated as is possible under this scenario there will be no Canadian Entitlement. It is unknown whether a Treaty scenario that removes all or part of the 7 Million acre-feet of storage at Arrow from the current 15 Million acre-feet of coordinated storage under the Treaty would be of interest to the U.S., or if valuation of other US interests such as navigation, recreation, irrigation and ecosystem function that Canadian Treaty Dam operations facilitate could partially (or fully) replace the Canadian Entitlement potentially lost due to reduced power generation in US plants.
– Decommissioning the HLK dam and ALG Station and restoring the Arrow Lakes reservoir to near pre-dam conditions would be unprecedented in scope and cost well in excess of $250M. Dam decommissioning or removal would not be necessary in order to address some of the total environmental or social concerns associated the facility and reservoir operation.