St. Mary's County Multi-Jurisdictional Hazard Mitigation Plan

Chapter 2: Hazard Identification
SMC Multi-jurisdictional Hazard Mitigation Plan
Wildfires and Urban Interface Fires
Overview
A wildfire is an uncontrolled fire spreading through vegetative fuels, such as brush, marshes,
grasslands, or field lands, exposing and possibly consuming structures. They often begin
unnoticed and spread quickly and are usually signaled by dense smoke that fills the area for
miles around. Wildfires may also be called forest fires. For the purpose of this analysis, the
term wildfire will be used. The causes of these fires include lightning, human carelessness, and
arson.
An urban-wildland
interface fire is a
wildfire in a
geographical area
where structures and
other human
development meet or
intermingle with
wildland or vegetative
fuels. Fires can be
rated based on their
degree of combustion
as noted in Table 4.10.
Table 4.10 - Fire Danger Rating Descriptions
Rating
Low
Moderate
High
Description
Fuels do not ignite readily from small firebrands although a more intense heat source, such as
lightning, may start fires in duff or punky wood. Fires in open cured grasslands may burn freely for a
few hours after rain, but woods fires spread slowly by creeping or smoldering, and burn in irregular
fingers. There is little danger of spotting.
Fires can start from most accidental causes, but with the exception of lightning, the number of fires is
generally low. Fires in open cured grasslands will burn briskly and rapidly on windy days. Timber
fires spread slowly to moderately fast. The average fire is of moderate intensity, although heavy
concentrations of fuel, especially draped fuel, may burn hot. Short-distance spotting may occur, but
is not persistent. Fires are not likely to become serious and control is relatively easy.
All fine dead fuels ignite readily and fires start easily from most causes. Unattended brush and
campfires are likely to escape. Fires spread rapidly and short-distance spotting is common. Highintensity
burning may develop on slopes or in concentrations of fine fuels. Fires may become serious
and their control difficult unless they are attacked successfully while small.
Historic Activity
Very High
Data from the
Maryland Department of Natural Resources Fire Service,
Southern Region Fire Center indicates a total of 982 fires
occurred in the County between 1985 and 2009,
damaging approximately 873 acres. The largest number
of fires occurred in 1995 (79 fires), which damaged over
100 acres of land within St. Mary’s County. Each year
there has been property damage including outbuildings,
automobiles, boats, propane tanks, fences, and porch
decks. Although houses were threatened by these
wildfires, they were all saved.
Fires start easily from all causes and immediately after ignition, spread rapidly and increase quickly in
intensity. Spot fires are a constant danger. Fires burning in light fuels may quickly develop intensity
characteristics such as long-distance spotting and fire whirlwinds when they burn into heavier fuels.
Table 4.11 - History of Fires in St.
Mary’s County
Year No. of Fires Acres
1990 11 11.3
1991 45 59.9
1992 64 34.2
1993 35 19.5
1994 45 72
1995 79 104.1
1996 22 10.2
1997 35 21.8
1998 40 30.9
1999 61 52.8
2000 17 10.6
2001 59 40.4
2002 57 32.8
2003 9 4.5
2004 23 23.8
2005 25 9.9
2006 55 12.7
2007 71 66.7
2008 36 12.8
2009 35 18.5
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