There are a few ways to view the floodplain mapping.  You can view the individual PDF versions of the maps, which are located under the Floodplain bylaw here.

You can also use the RDKB’s Interactive Map, which is located here.  In the Interactive Map, you can select the “Hazards” layer to display the information in the same way it is shown in the bylaw.  You can also select the “simplified floodplain mapping” layer.  Click here to learn more about how to read the “simplified floodplain mapping” layer.

This layer compiles some of the floodplain data together to make it easier to see and know how the floodplain bylaw applies to any particular property or area.  It simplifies the information of the mapping’s key components.  Click here to learn more.

When constructing, renovating or altering a building or structure near a body of water, there are five key components to consider: Flood construction level (FCL), setbacks from the natural boundary, high fluvial hazard extent, floodway and alluvial fan.  See below for further explanations of each.

FCL is a specified elevation (height) above a natural boundary.  Depending on where the parcel is located (and whether mapping has been done), this is either an elevation specified in the mapping, or a specified height above the natural boundary of a body of water, or an elevation specified in the bylaw.  See Section 403 of the bylaw for details.

This is the area where a minimum elevation is required because of the likelihood of flooding to occur.  It is mapped to show the areas of what is called the “200-year floodplain”, being the area with a 0.5% chance of being flooded in any given year.  It includes a “wave effect zone” for Christina Lake.  The “wave effect zone” increases the minimum elevation based on modelling of how wave action would influence flooding potential.

The natural boundary is determined by a BC licenced land surveyor.  It is defined in the Land Act and our floodplain bylaw.  In simple terms, it is where the vegetation and ground characteristics start to change from being part of the foreshore (aquatic) to being upland (terrestrial).

These are specific setbacks related to a body of water’s natural boundary (not the same as a zoning setback).  The setbacks from the natural boundary in the bylaw are:

• 30 m for most of our large rivers (Columbia River, Kettle River, West Kettle River, Granby River, and specified sections of the Pend d’Oreille River)
• 10 m for ponds, wetlands, and lakes (including Christina Lake)
• 15 m for other steams, creeks, rivers and any other watercourses not listed above

These setbacks are not mapped but some information about them is in the pop-up on the “interpretive floodplain” layer of our mapping.  This is because the natural boundary of a body of water can change over time so it makes accurate mapping difficult.

A “high fluvial hazard extent” is an area that is mapped along some rivers.  In simplified terms, it is an area that could erode during a flood event.  It is an area where no building/structures are to be built.

In simplified terms, this is an area that is part of an active river plus any areas that are likely to have either lots of water or fast moving water during a flood event.  It is an area where no building/structures are to be built. 

Not to be confused with a fluvial hazard, an alluvial fan is the area where a stream has deposited upstream materials (soil, sand, earth, debris), typically in a fan shape, due to coming from a narrow or steep area and spreading out over a plain.  In the RDKB we have mapped only some alluvial fans around Christina Lake.  The four rated alluvial fans are mapped and are: Texas Creek, McRae Creek, Sutherland Creek, and Moody Creek. 

With few exceptions, any building or structure within a rated alluvial fan that is rated “High Fan Hazard” or “Very High Fan Hazard” must have a professional report completed before getting a building permit (see Q&A on Alluvial Fan Assessments and Terms of Reference for more info).

Yes, there are lands where the floodplain bylaw does not apply.  This includes:

• lands further from a body of water than a required setback, and above the specified flood construction levels, and outside an alluvial fan hazard (see explanation below)
• lands periodically flooded for agricultural purposes
• lands next to seasonal watercourses with a limited drainage area and very low banks (see watercourse definition in bylaw for exact specifications)

Yes, the floodplain bylaw does not apply to the following:

• landscaping
• paving and pavers
• fences
• retaining walls under 4 feet (1.22 m) in height

There are also some exceptions laid out in the floodplain bylaw for specific activities (see below).

What are the exceptions for flood construction levels?

There are some exceptions in Section 404–General Exemptions that apply to the FCL only.  Floodplain setbacks still apply.

• New buildings and structures: Garages and carports; domestic greenhouses; domestic storage buildings; entryways and porches; open-sided recreation shelters; open-sided livestock structures; farm buildings; closed-sided livestock housing with floor no lower than 1m above ground.  Most of these exceptions limit use within the building to storage of goods that can’t be damaged by flooding or storing vehicles – see bylaw for details.
• Existing buildings and structures with no permit: Buildings and structures must be documented as lawfully constructed to qualify for an exception.  Typically, this is proof of a building permit but other documentation may be acceptable. If a building permit was required but never received, then the FCL exceptions do not apply.
• Existing buildings that were lawfully constructed: FCL is not applied to non-structural alterations, structural alterations that don’t add any habitable area, and carports/garages (used only for vehicle storage or storage of goods not damageable by floodwater).  The FCL also does not apply to minor additions (lesser of 50 sq. m. or 25% of floor area of the building), under certain conditions: see Section 404.1(b) of the bylaw for specifics.

The only new buildings and structures exempt from providing an alluvial fan assessment are those 10 sq. m. or less (108 sq. ft.). 

For existing building and structures, exemption to the alluvial fan report requirement only applies to those that were lawfully constructed; and then, only for non-structural alterations, structural alterations that do not add habitable area, or carports/garages used only for storage of vehicles and goods not damageable by floodwater.

A property owner has the right to apply for a site-specific floodplain exemption.  Granting an exemption is at the discretion of the RDKB Board of Directors, based on whether they consider it advisable.  In alignment with the Local Government Act, a report from a qualified professional is required as part of the application if the exemption is not consistent with provincial guidelines.  The report is to include an engineer’s recommendation and mitigation.

Application forms and additional info can be found here: https://rdkb.com/Plan-Build/Planning/Application-Forms 

Copies of previous floodplain exemption reports are available here.    

Alluvial fan reports are also available here.