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Water birch has mixed fire evidence.
Several western programs treat it as fire resistant, but Idaho’s field trial gives it only 4 of 10.
Four programs support planting it in fire-conscious landscapes. FireSmart BC approves water birch as fire resistant, while the University of Nevada’s extension compilation includes it because at least two cited sources rated it favorably. The University of Arizona lists it among fire-resistant plant materials above 3,000 feet. New Mexico’s Forestry Division also includes it, marking it suitable from 5,000 through 8,000 feet, with suitability unknown or doubtful at 4,000 feet and 9,000 feet or higher. That list identifies its water need as high.
The caution comes from Idaho Firewise, whose scale maps the fire-resistance score to a minimum planting distance. Water birch scored 4 of 10, within the scale’s mixed band of 4 through 7 rather than its recommended band of 8 through 10. This is a different kind of judgment from appearing on a compiled plant list, so the favorable listings and the modest trial score are not measuring the plant in quite the same way.
Water birch is therefore a qualified choice rather than a clear fire-resistant standout. Its approval across several regional lists supports considering it, especially where their elevation guidance applies, but the Idaho score argues for caution about placing this high-water tree close to a structure.
Form
tree
Mature height
~25 ft
Water need
high
Rated in
Arizona above 3,000 feet / interior Southwest; British Columbia; Nevada / Great Basin; New Mexico +1
On this lot
1. Fire evidence and conditions
Fire evidence
Mixed evidence — location does not change the cited classification.
Southern Idaho (ID footprint); partial normalized coverage · 2013-11-08
The official database labels itself "For Southern Idaho" and describes Idaho residents at the urban-rangeland interface. FireApproved publishes 419 existing plant owners that cite its scored rows. This bounded Southern Idaho scope is regional context, not statewide coverage or a conclusion that the score transfers unchanged to every Idaho site.
New Mexico Forestry Division publishes this as its FireWise Plant List for New Mexico. FireApproved accounts for all 140 printed rows and publishes 95 exact same-rank owners already represented in the directory; 29 exact taxa without an existing record, 14 unresolved spellings or higher-rank matches, one compound taxon cell, and one species row whose only apparent owner has an infraspecific printed identity remain held. Every published row retains the source's Y, N, ?, or blank elevation cells. Publication scope does not erase those elevation limits or establish suitability for every New Mexico site.
Arizona at or above 3,000 feet (AZ footprint); partial normalized coverage · 2011-12-01
AZ1289 is explicitly limited to Arizona elevations of 3,000 feet and higher. FireApproved publishes 69 exact owners as regional Arizona context, retaining every water and elevation condition. It is never promoted to statewide low-desert guidance or an independent Tier 1 vote.
University of Nevada Cooperative Extension compiled plants suited to Nevada climate zones and reported favorably by at least two upstream firewise lists. FireApproved publishes 126 exact source owners at Nevada publication scope. The source explicitly makes no independent flammability determination, so these rows remain corroborative.
2. Why this plant is relevant here
State distribution
Documented in AK, AZ, CA, CO, ID, MT, ND, NE, NM, NV, OR, SD, UT, WA, WY.
Native range
Current cited native range in AK, AZ, CA, CO, ID, MT, ND, NE, NM, NV, OR, SD, UT, WA, WY.
Introduced / established
USDA hardiness
An exact source temperature is retained below the published zone scale; no zone is invented.
3. Legal, ecological, and broader status
Legal-list status
Seed-list status
Reported invasive here
Broader regional context
Federal context
How to read this page
The status above is computed from the cited rows below: independent recommendations can support a fire-resistant result, an avoid row can produce keep-away, and disagreement stays visible as conflict. Placement notes preserve each source’s own scheme rather than translating unlike rules into one scale. This is evidence about a plant, not permission to plant it in every part of the defensible space; Zone 0 remains noncombustible.
Native and introduced range evidence
These are exact U.S. botanical-area records from the cited range source. Native and
introduced describe biogeographic relationship, not fire performance or planting approval.
Doubtful and extinct rows stay visible but do not count as current presence.
The lossless worldwide derivative is retained once in the research corpus; object pages repeat only exact U.S. areas needed by the local lens. The JSON twin carries the same page assertions.
Plant hardiness evidence
These values describe the plant source. Your ZIP zone comes from the separate 2023 USDA
Plant Hardiness Zone Map. Whole-zone values stay whole-zone, and a single unresolved value
is not treated as a tolerance range. Different source boundaries stay separate: overlapping
statements are compared independently, while only ranges with no shared zone are called a conflict.
Exact minimum -62°F · below the published zone scale · half zone precision · below published scale
Source taxon: Betula occidentalis · source identifier match.
Source location: PlantCharacteristics record 69998, Temperature, Minimum (°F).
Where its sources say to plant it
Placement rules below use each source's own distances or named zones, tied to its rating.
They are not interchangeable with the directory's current Zone 0 guidance.
Fire Resistance of Plants Master Database: plantable at 70' from home [Idaho minimum planting distance] (mid-scale rating)
FireSmart BC Plant Program: suitable for HIZ extended zone and beyond [FireSmart BC Home Ignition Zone] (with its recommendation)
FireWise Plant List for New Mexico: PDF page 3, Trees and Large Shrubs, p3-r07 [nm-emnrd-firewise-table-row] (with its recommendation)
The evidence
Grouped by what each source concluded. Primary evidence rated the plant itself
(a lab, field program, or original curation); corroboration compiled or
republished another source's rating and resolves to its root lineage.
Listed among fire-resistant plant materials for Arizona above 3,000 feet.
FireWise Plant List for New Mexico — New Mexico Energy, Minerals and Natural Resources Department, Forestry Division · 2003 Forestry Division PDF · original sourceCorroborationCompilationlineage: csu-nmsu-firewise
“FireWise Plant List for New Mexico”
Listed as Betula occidentalis (Water birch) in Trees and Large Shrubs. Printed elevation cells: 4,000 ft=?, 5,000 ft=Y, 6,000 ft=Y, 7,000 ft=Y, 8,000 ft=Y, 9,000+ ft=?. Water need: H; sun/shade: S/PS; mature height: 6-10’; approximate bloom: n/a.
