Okanagan Lake’s natural shoreline slowly vanishing

A large portion of Okanagan Lake’s shoreline is still in a relatively natural state, but researchers say an increasingly larger portion has been disturbed, leaving less and less natural habitat.

A large portion of Okanagan Lake’s shoreline is still in a relatively natural state, but researchers say an increasingly larger portion has been disturbed, leaving less and less natural habitat.

About 57 per cent of the lake’s shoreline has been disturbed to varying degrees, according to the results of a yearlong project to map and create an inventory of the 289 kilometres of shoreline to describe, among other things, the level of human impact.

“The most important thing to keep in mind is that the rate of change is two per cent per year,” said Carolina Restrepo-Tamayo, program co-ordinator for the Okanagan Collaborative Conservation Program, the group that sponsored the study. “The good news is that 43 per cent of our shoreline is intact. But if we continue changing at the rate it has been changing, let’s say in 20 years, we will have 100 per cent of the shoreline disturbed.”

That two per cent rate was determined by comparing the results of the current mapping project with data collected in 2004, when just the Central Okanagan portion of the lake was subjected to foreshore inventory mapping.

The lake is one of the most important resources shared by communities throughout the Okanagan Valley, contributing significantly to the overall economy of the valley. Besides its recreational value, Okanagan Lake is a primary source of water for agricultural purposes and a major source of drinking water for residents.

The Foreshore Inventory and Mapping project, which also included an aquatic habitat index, began in February 2010 and finished this last February, with a 780-page report detailing the results released last week.

More than 2,700 docks were counted in the survey, the most common modification to the shoreline. Retaining walls came in second, with 1,800 covering about 20 per cent of the length of the lake. Other modifications include reconstructions of the lakeshore to improve access or create beaches, typically using lakebed cobbles and boulders. In total, about 47 per cent of the lakebed had been modified to some extent.

Restrepo-Tamayo said communities around the lake, with this detailed information in hand, should now be looking to preserve the remaining 43 per cent of natural shoreline and perhaps recover part of the other 57 per cent. That doesn’t mean, though, removal of the construction that is already there.

“I don’t think that is the main solution,” she said. “The important thing is we need to create consciousness of the kind of modifications to the lakeshore.”

She said it is possible to promote ways of continuing to use and enjoy the lake, but doing it in a manner that helps protect the shoreline in other ways.

“Our goal with this project is to help local governments to make better decisions in terms of land use planning, like getting information to the public about how they can help to protect or maintain the shoreline,” said Restrepo-Tamayo. “Different municipalities sometimes have different regulations, but at least we can provide a whole base that gives them better tools and better decisions for the shoreline.”

In order to provide more collaborative lake planning and management, the OCCP, with support of senior governments, as well as the Okanagan Basin Water Board, started the process to document the current condition of the foreshore, the relatively narrow strip of land at or near the high water mark of a body of water.

The foreshore is a productive area considered essential to natural processes including the lake fishery, its wildlife and water quality.

The complete report are available from the Okanagan Collaborative Conservation Program website at www.okcp.ca.