Catron County Community Wildfire Protection Plan
VOLUME 2 (Planning_)

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Methodology for Establishment of Wildland Urban Interface (WUI) Boundaries

I. Introduction

The identification of WUI boundaries was one of the more difficult aspects of the analysis. There are many versions of WUI definitions and boundaries. WUI maps have been made at various times for differing purposes by each of the agencies involved. Some prior maps were made before and some after the Healthy Forest Restoration Act (HFRA). Besides the obvious concern of protecting values at risk, there are political, funding and accomplishment target implications to be considered. The process described below was used to develop a collaborative identification of WUIs.

II. Definitions

The definitions in HFRA for “at risk community” and “WUI” were used as guidelines. The following definition was developed early in the process by the analysis team to apply specifically to this plan.

DEFINITION OF WILDLAND URBAN INTERFACE (WUI)

An area in or adjacent to an at-risk community including isolated parcels of private property containing structures, infrastructure, or watershed with topographic features and fuel conditions (fuel type, fuel loading and arrangement) that have the potential to endanger that community.

The criteria to be used when establishing WUI boundaries are:

1. Fuel Hazard Threat Level

2. Risk of Occurrence

3. Values at Risk

III. Boundaries Mapping

Boundaries were mapped using a three step process.

1. All E911 address points were buffered by 1/4 mile radius. Every address was included, no matter how many structures were involved or what the risk from wildfire. All homes are important regardless of the level of risk and the treatment priorities. Priorities for treatment based on the level of risk can be more easily justified than justifying WUI status for x+1 structures but not for x structures. For example a one E911 address WUI in grassland will have a much lower treatment priority than a WUI with several hundred addresses in ponderosa pine forests.

2. The resulting polygons from the buffering were then adjusted to produce a draft WUI map using the following guidelines:

a. Addresses in grassland and desert shrub areas remained at about the 1/4 mile buffer or were increased to no more than 1/2 mile.

b. The buffered boundaries around addresses in other vegetative cover types were adjusted after consideration of such factors as slope, aspect, vegetative cover and number of addresses needing protection plus the need to protect evacuation routes.

c. The general philosophy at this stage was to make an estimate of the minimum area believed necessary to give defensible space to firefighters in the event of a wind driven catastrophic wildfire. The objective being to have the majority of spotting fall out and a crown fire to drop down before reaching the homes/structures being protected. In general WUI boundaries in pinyon-juniper were drawn at about 1/2 to 1 mile and ponderosa pine-mixed conifer was drawn at about 1 to 1.5 mile or further where it was believed necessary.

3. Review and discussions about the draft map revealed the need for revision of the draft map for several reasons:

a. Local knowledge about the densities, mix of tree species, ground fuels, slope, aspect, etc. indicated a need to change some of the boundaries.

b. In some cases where prescribed burning is the most feasible treatment method, there was a need to adjust the boundaries to features like roads, ridge tops and canyon bottoms where control lines for the prescribed fires would be most feasible, cost effective and environmentally acceptable. Also in some instances there was a need to place the boundaries on defendable features for the purpose of stopping an advancing wildfire. In some cases these changes extended the boundaries considerably simply because of large areas of rough terrain with no roads.

c. In some areas, E911 data missed significant amounts of homes/structures that needed to be added. WUIs were added to account for these as best as could be determined by local knowledge.

d. Some evacuation routes needing protection were added.

e. Two other items discussed but not included in WUI boundaries were communications sites and potential development (vacant private land within the National Forest lands). Communication sites are being considered as part of the determination of treatment priority for WUIs. As for the undeveloped private land question, it was agreed that the definitions of “at risk communities” in HFRA would exclude such from being considered.

f. Where WUI areas became quite large, they were split where possible into areas of like treatment priority. This was done partly to make the process used to determine treatment priorities more meaningful.

IV. Boundaries Identification

HFRA states the boundaries of WUI areas may be as identified by a Community Wildfire Protection Plan. Under the provisions of the Healthy Forest Restoration Act, a WUI boundary is up to 1.5 miles wide unless a larger need is identified in a Community Wildfire Protection Plan. Some of the boundaries go out 2-3 miles where there is justifiable reason. All boundaries were reviewed by the applicable agencies. All suggestions for change of the draft map were able to be incorporated in the final draft.

The WUI boundaries have been mapped in this plan to the best of our present knowledge and abilities. Planning of actual fuel hazard reduction and forest restoration projects, new data, new subdivisions, new development and other changes will necessitate the addition of new WUIs and modification of existing WUI boundaries. It is not the intent of this plan to force the land manager or firefighter into unsafe, ineffective, inefficient or environmentally unacceptable actions for the sake of following this plan. There are certainly enough WUI boundaries in the County and documentation to guide changes as needed. This plan further identifies the following areas as being within WUI boundaries:

a. Areas resulting from adjustments to place the control line for prescribed fires (and/or wildfire) in safer and more efficient locations.

b. Areas resulting from adjustments when the planning of implementation projects reveal a justifiable change based on better field data and a more detailed analysis of predicted fire behavior than was available to this planning process. A justifiable change would be one that would better provide defensible space as described in III.2.c. above.

b. New WUI boundaries needed for missed structures and new subdivisions and other development using the above documentation and established WUIs as guidelines.

It is suggested that a short explanation of such reasonable changes be placed in the project record to document compliance with the WUI guidelines of this plan.

V. Other Notes on Drawing of WUI boundaries

There was a question on whether to include power lines, communication sites, etc. as WUIs if outside "community" WUIs. After reviewing the definition drafted by the analysis team, it was decided to draw WUIs only around "communities". Power distribution lines and communications sites were mapped and rated appropriately in the value matrix for a WUI and/or watershed. Power lines to a community, subdivision or WUI were counted as a distribution line but "branch" lines within a community, etc. were not.

The need for protection of evacuation routes and safety zones were also rated appropriately for each watershed and WUI (an evacuation route needing protection may be but not necessarily all in the WUI boundary). Evacuation routes and safety zones were not mapped. That task is saved for project level planning. Each WUI was rated for the Evacuation/safety zone attribute as in the Value Matrix. Each subdivision and community in the County was rated in a table for evacuation and safety protection need. The highest need for protection will be recorded in the rating for a WUI or watershed.

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