Okanagan Lake water regulation system needs updating

Province has received report on process for moderinizing Okanagan Lake Regulations System

Flooding and sandbag retaining walls have become a familiar occurrence across the Okanagan Valley in recent years. (File photo)

The conflict between managing the Okanagan Valley watershed for flood control against other environment protection and fisheries enhancement interests has evolved into a more complementary rather than a conflicted relationship.

Brian Guy, a retired engineer, says modernizing the ageing Okanagan Lake Regulations System (OLRS) infrastructure should take that into account.

He said none of the watershed restoration efforts of the last 20 years has impeded the ability to control flooding, the overriding objective when the OLRS was established starting in the 1950s.

The restoration efforts, in particular along the Okanagan River segment connecting Skaha Lake to Osoyoos Lake, initiated by the Okanagan Nation Alliance, have led to a resurgence of the sockeye salmon fishery.

The ONA has carried out five different river restoration projects since introducing the restoration concept to water management officials at a workshop held in 1997.

“Prior to 2008, the Okanagan sockeye salmon return never exceeded 100,000 in all but two of the previous 48 years, but it has exceeded 100,000 adults in all years since 2008,” said Guy.

“This impressive restoration effort makes you wonder what other restoration ecosystem benefits can be achieved without impacting the other benefits the system was created for such as flood control and providing a stable irrigation water source for farmers.”

Guy has produced an analysis for the Ministry of Forests, Lands, Natural Resource Operations and Rural Development on how to modernize what has become an ageing infrastructure system with working models, developed in the 1970s, ill-equipped to deal with snow and rain extreme weather conditions introduced to the watershed by climate change.

“It’s getting older and harder to manage,” he said.

He made a presentation of his report to the Okanagan Water Stewardship Council last month.

His report calls for a series of 13 core studies and four supporting studies, done over a seven-year period, feeding information into a final plan on how to proceed with an ORLS infrastructure modernization overhaul in a coordinated and well-thought-out manner.

When the analysis is done and a modernization plan is in place, Guy stated that a leadership group should be struck to oversee its implementation.

According to Guy, the cost estimate for the preliminary study work has yet to be worked out, as it will depend on what outside support the province would retain to complete the study series.

All communities across the watershed should be invited to participate in the study analysis, placing particular significance on the contribution from Indigenous stakeholders in the watershed management such as Okanagan Nation Alliance.

“When the basin study upon which the lake level models were developed in the ’70s, there was no consultation with the Sylix people. But times have changed and environment protection values have taken on more importance,” Guy said.

The ORLS has evolved into three controlled dams – at Okanagan, Skaha and Vaseux lakes – along with 17 vertical drop structures and 32 kilometres of engineered channels between Penticton and Osoyoos to control flooding and Okanagan River flow, at the cost of alienating floodplains and a loss of riparian vegetation.

Channelizing the Okanagan River from Penticton to Osoyoos has reduced the wetland area from 81 to 10 hectares, 90 per cent of the riparian vegetation is gone and the floodplain width average has reduced from 400 to 45 metres.

“Some serious alterations were created by the river channelization with impacts on the floodplains and all the biological processes that occur on those floodplains,” Guy said.

He said the influx of people who have moved to the Okanagan over the last 20 to 30 years probably have little awareness of how the lake levels varied significantly before the control measures were put in place to control the outflows.

“I suspect there is not a widespread understanding of how significant the flood control and irrigation benefits are of the OLRS, or what impact that had on (Okanagan River) and the floodplain…of what has been lost.”

Concerns were further triggered by a floodplain mapping report by Northwest Hydraulic Consultants for the OBWB, which said floodplain levels were not sufficient to absorb high water levels in 2017 expected to become the norm rather than the exception.

“That produces risks for the fish, for farmers and other valley lake users. These are issues that have not yet been properly examined,” Guy noted.

READ MORE: Funding sought for Okanagan Lake management study

READ MORE: Okanagan facing extreme flooding risk

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B.C. Floods 2021Okanagan