The Regional District has, since at least 1982, regulated development within the floodplain associated with various watercourses (e.g. lakes, rivers and streams) in the Electoral Areas through its zoning bylaws.

The mapping that the Regional District has historically relied on to establish floodplains associated with Okanagan Lake, Skaha Lake, Vaseux Lake and Osoyoos Lake as well as the Okanagan River Channel were prepared by the provincial government in the 1980s and 1990s. For any land not shown on the provincial floodplain maps — such as Park Rill Creek, Horn Creek and Kearns Creek — the Zoning Bylaw has designated the following as “floodplain”;

• and that is less than 3.0 metres above the natural boundary of the Okanagan River and the Okanagan River Channel; and
• any land that is less than 1.5 metres above the natural boundary of any other watercourse.

Park Rill Creek, Horn Creek and Kearns Creek Flood Mapping Report

In 2022, the Regional District received the Park Rill Creek, Horn Creek and Kearns Creek Flood Mapping Report which was prepared by Northwest Hydraulic Consultants Limited  in response to the flooding that occurred within the Park Rill Creek, Horn Creek, and Kearns Creek watersheds during the 2018 freshet.

The main objectives of this project were to:

• Complete hydrologic and hydraulic modelling of the watersheds.
• Prepare detailed floodplain and flood hazard maps for the areas of Twin Lakes, Willowbrook, and Sportsmens Bowl Road.
• Assess the associated consequences of flooding.
• Identify mitigation measures.
• Complete a visual inspection of a 12 km reach of Park Rill Creek between near Twin Lakes and Willowbrook.

The main recommendation of the report is that “the designated floodplain maps [contained within the Report] should be adopted for flood planning purposes, including establishing flood construction levels.”, on the basis that the new floodplain maps could "limit increased flood risk from unmitigated and/or unrestricted development of the floodplain.”

It is being proposed to include a new floodplain map to the Okanagan Valley Zoning Bylaw No. 2800, 2022 for floodplains associated with Park Rill Creek, Horn Creek and Kearns Creek and amend Section 10 (Floodplain Regulations) of the Zoning Bylaw based on the new mapping produced by Northwest Hydraulic Consultants.