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Summary of Fire Impacts on San Diego

[Note: During the month of October, 2007 nine separate fires burned various parts of San Diego County, many burning simultaneously. Presented below in summary form are major impcts of the four largest fires, presented in event order: Harris Fire, Witch Fire, Rice Fire, and Poomacha Fire.]

Soure: Grossmont Community College (2007)

Jump to:

Harris Fire

Witch Fire

Rice Fire

Poomacha Fire

 

Harris Fire

The Harris Fire burned 90,440 acres between October 21 and October 31, 2007 in the southwest section of San Diego County, and along the U.S./Mexico border (see Map). Areas burned were primarily rural with pockets of wildland-urban interface. During the ten day burn event, there were 459 structures and 293 outbuildings were lost, and 587 vehicles were destroyed. There were also five civilian deaths, 21 civilian injuries and 34 firefighter injuries.

Photo by Nancee E. Lewis/San Diego Union-Tribune

Harris Fire near Barrett Junction heading west from its starting point of Potrero (October 21, 2007)

Topography within the burn area ranged from gentle alluvial valleys to very steep headwater basins. Topographic relief is moderate to high. Some of the slopes are very steep, up to 167 percent. The elevation range of the burn area was 245-3885 feet above sea level. Most of the burn event was at a low to moderate burn severity, with islands of unburned areas. For the entire burn area of 90,440 acres, 0.1% was rated as high burn severity, 36.5% as moderate severity, 59.2% as low severity, and 4.15% was unburned (within the burn perimeter).

Three watersheds and ten sub-watersheds were involved in the burn, including Sweetwater Marsh sub-watershed, Sweetwater Reservoir, Otay Reservoir, Jamul Creek, Otay River sub-watersheds, Lower Pine Valley, Cottonwood Creek/Lake Morena, Cottonwood Creek/McAlmond Canyon, Cottonwood Creek/Potrero Creek, and Campo Creek. Three major reservoirs were located at the edge of the fire perimeter including Barrett Lake, Lower Otay Reservoir, and the Sweetwater Reservoir.

Photo by K.C. Alfred/San Diego Union-Tribune

Harris Fire burns near Lyons Valley (October 26, 2007)


Relative impacts to habitats and sensitive plant species varied considerably due to topography, elevation, differences in fuel types, and changes in wind direction during the fire event. The general extent and severity of the fire’s impact to habitats were greatest in the northwest corner, north, and southeast of the burn area (see BAER Team Fire Burn Severity Map). Much of the western half of the fire, delineated roughly by the South County/East County MSCP boundary, consisted of coastal sage scrub habitat with grassland at lower elevations. Chaparral typically grows in shallow soils and higher elevations. Vernal pools were situated in Marron Valley and east of Lower Otay Reservoir. Freshwater marsh were found along Otay and Sweetwater Reservoirs, as well as within pools along perennial streams. The eastern half of the Harris Fire was dominated by xeric chaparral in shallow soils, and higher elevation oak woodlands with mixed riparian woodlands along drainages. Burned area vegitation consisted primarily of chaparral, chaparral with widely scattered oaks, coastal sage scrub, riparian oak-sycamore woodland, Coast live oak woodland, mixed conifer forest (Cypress), and grass land. The following table summarizes habitat loss.

   

Photos by John Gibbins/San Diego Union-Tribune

Retardant dropping helicopters working above Lyons Valley (October 26, 2007)

Table 1:

Summary of Habitat Acres Burned

   Habitat
Acres Burned
Coastal Sage Scrub
31,752
Grassland
2,461
Riparian
1,701
Other Wetlands
428
Chaparral
46,111
Oak Woodlands
2,614
Mixed Conifer Forest
725

This summary of the fire impact was based on the burned area emergency rehabilitation (BAER) team assessments immediately following the fire. The teams examined houses, infrastructure, roads, reservoirs, watersheds, and other natural and cultural resources within or near the fire boundary, in order to determine whether there were significant risks to assets, and to offer treatment/mitigation recommendatioins to appropriate state and local agencies. This was a rapid assessment conducted by a multidisciplinary team of experts for the purpose of assessing fire impacts on and threats to 1) human life and safety, 2) property, and 3) water quality, soil, wildlife and fisheries, botanical values, and cultural resources. The BAER report in its entirety, including specific recommendations for minimizing undesirable post-fire effects, is referenced and viewable below as a pdf document.

 

Photo by Nelvin Cepeda/San Diego Union-Tribune

Firefighters from Ventura work blaze near Honey Springs Road in Jamul (October 24, 2007)

Vegitation

The burn area included plant and animal communities found in both upland and lowland habitats. Upland habitats are at higher and dryer elevations, more fire prone, and support plant types that are adapted to cycles of drought. These include Coastal sage scrub, grasslands, chaparral, and oak woodlands habitats, as well as integrated habitats. Fire impacts to upland habitats are expected to be direct and recovery will depend on tolerance to fire, including for plants resprouting and regeneration (e.g., seed banks, tubers, corms, rehizomes).

 

Lowland habitats are found at lower elevations and are that wetter, and include or more watershed drainages, such as, riparian woods and scrub habitats, freshwater marshes, and vernal pools. Lowland habitats are expected to experience indirect fire effects due to less outright fire-burned acreage. Additional indirect affects will occur, subsequently, due to runoff and erosion, with these concentrated in the downslope drainage basins.

Upland Habitats
Coastal age scrub and chaparral habitats generally burned at a moderate to high severity with greatest habitat impacts in the north, northeast, and southeast portions of the burn area. The greatest threat to upland habitats is type-conversion to non-native grasslands. Such type-conversion (e.g. Coastal sage scrub to non-native grasslands) may occur because of increased fire frequency. Non-native grasses grow opportunistically and outcompete native vegetation for resources. This conversion to non-native grassland also increases the fire frequency of the site and perpetuates itself by causing short fire cycles, precluding succession to other habitat types. Non-native grasses are considered a “flashy fuel” and can be ignited easily on a more frequent basis.

Habitat conversion is occurring along the U.S. – Mexican border due to greater fire frequency. Areas burned in the 2003 Otay Fire that have re-burned in the Harris Fire are at extreme risk of habitat conversion, including areas known to be occupied by Tecate cypress.

Of the three Tecate cypress populations in San Diego County, two were affected by the Harris Fire. Most, if not all, of the Tecate cypress on Tecate Peak burned in the Harris Fire. The majority of the Otay Mountain population burned in the 2003 Otay Fire, and is currently supporting 4-year-old seedlings. However, several mature trees along the western slopes of Otay peak, not burned in 2003, were lost in the current fire. While Tecate cypress can live up to 200 years, they are not well adapted to withstand frequent fires. A fire cycle at a minimum of 35 years is considered necessary for population viability (Esser, 1994). At the current fire frequency rate, the regeneration cycle of the Tecate Cypress is at extreme risk.


Lowland Habitats
Riparian habitats generally varied in severity from low to moderate with some high severity areas within Dulzura Creek, Cottonwood Creek, Rattlesnake Canyon, and Potrero Creek. Vernal pools in Marron Valley and east of Lower Otay reservoir were largely unburned or sustained low burn impact.


Approximately 5,000 acres of the Rancho Jamul Ecological Reserve (88 percent) burned, including sage, grassland, and riparian habitats. The burn on Rancho Jamul Ecological Reserve was generally light to moderate in severity, with some riparian areas burned at a high severity level.

In the Hollenbeck Canyon Wildlife Area, adjacent to Rancho Jamul Ecological Reserve, 4,500 acres burned (82 percent). This area sustained light to moderate burn severity in similar habitats.


Otay Mountain Ecological Reserve had light to moderate burn severity throughout its Coastal sage scrub, grassland, and riparian habitats.

Riparian and wetland lowland habitats are at high risk from the fires, due to opportunistic exotic plants, including Giant reed (Arundo donax) and other non-native grasses and forbs. These plants frequnetly out-compete natives after fire events. Risk to the other listed sensitive plants (see below) will generally depend onthe burn intensity and severity as it relates to seed survival and survival of existing perennial plant rootstocks.

Sensitive Plants at Risk

Interagency State Burned Area Response (BAER) Report (2007, November 20)

View of some of the burn area from Mt. Miguel (looking West)

Geology/Hydrology

A principal concern with the Harris fire is the potential for in-channel floods, hyperconcentrated floods, debris torrents, debris flows and rock falls. Houses located in drainage swales at the bottoms of canyons are at obvious risk for debris flows and flash floods. Several houses lie below burned, steep, slopes that contain numerous boulders. Other houses spared in the fire occupy floodplains (i.e., Cottonwood Creek and Potrero Creek) below burned watersheds and are at a higher risk of flood and sediment damage until hillside vegetation is re-established. The magnitude of post-fire damage will be determined by the intensity and duration of winter storms. The increased runoff and erosion will result in higher than usual peak flows along stream channels.


Relatedly, Skyline Truck Trail, Lyons Valley Road, Honey Springs Road, Otay Lakes Road, and Barrett Lake Road may be subject to inundation in some areas due to existing drainage structures becoming overwhelmed by increased streamflows carrying sediment and/or debris. Local roads, particularly Barrett Lake Road, could be subject to rock falls and earth slides originating from slopes in the immediate arera. County and private roads in the communities of Dulzura, Engineer Springs, Barrett Junction, Potrero and Tecate may also be subject to minor to moderate sedimentation due to increased erosion in the adjoining areas. Access for border patrol and fire response roads along the Mexican border may also be interrupted due to washouts or overwhelmed drainage structures.

Photo By Jim McVeigh

Harris Fire lights up Otay Lakes (Otober 23, 2007)

Topography and soil types found predominately in the burn area add to the likelihood of flooding and debris flows. High soil burn severity produces hydrophobic conditions, particularly with coarse textured soils. After intense heating a hydrophobic layer is produced when a waxy substance derived from plant material burned during a fire penetrates into the soil as a gas and forms a waxy coating around soil particles. Hydrophobic soils repel water, reducing the amount of infiltration that can occur, resulting in increased winter peak storm flows and significant soil erosion. Depending on the intensity of the fire, hydrophobic layers can persist for a number of years, especially if they are relatively thick. The hydrophobic layer is generally ½ inch to 3 inches beneath the soil surface and is commonly as much as 1 inch thick.

Another expected consequence of the fire is flooding due to overwhelmed drainage facilities from increased runoff, sediments, ash, and debris entering riverine systems, roadway culverts and low lying areas.

The flooding also may affect water quality at specific sites and downstream along the draining waterways, creating significant secondary concerns. Water quality can be adversely affected by polluted runoff containing ash and soil, as well as hazardous waste runoff from burned homes, vehicles, and public facilities. The proximity of the fire on the slopes of San Miguel and San Ysidro Mountains to water supply reservoirs serving large numbers of people may require monitoring and mitigation to prevent significiant reductions in water quality.

Interagency State Burned Area Response (BAER) Report (2007, November 20)

Western face of Lyons peak following the Harris Fire

Wildlife

The Harris fire burned across state, federal, and private conservation lands. State lands including Rancho Jamul Ecological Reserve, Hollenbeck Canyon Wildlife Area, and portions of Otay Mountain Ecological Reserve. Federal lands included Cleveland National Forest, Otay Wilderness Area, South San Diego Wildlife Refuge, and Mount Miguel Wildlife Refuge. Significant local and private conservation lands included Sweetwater Reservoir, and the City of San Diego’s Marron Valley. The western portion of the fire, roughly west from Barrett Junction, is included in the approved South San Diego County Multiple Species Conservation Plan. The eastern portion is located in the East County MSCP, which had not been completed at the time of the fire event.

Wildlife species affected by the fire included Coastal sage scrub species, desert chaparral species, and riparian species. Species of special interest in the burn area included:

Sage scrub/chaparral species
• Coastal cactus wren (cactus dominated sage scrub)
• Coastal California gnatcatcher
• Quino checkerspot butterfly
• Thorne's hairstreak

Riparian Species
• Arroyo toad
• Least Bell’s vireo

Upland Habitats
Within the western half of the fire, upland habitats (i.e., grasslands and sage scrub) generally burned at a low severity. Several locations including Otay Lakes, Marron Valley burned in a mosaic pattern leaving a majority of the areas of brush unburned.

Areas north of Sweetwater Reservoir and River, on Sweetwater Authority and U.S. Fish and Wildlife Refuge (Mount Miguel), including a significant portion of the willow riparian habitat, burned at a moderate severity. The recent burn of these areas in 2003 can account for the low severity of the burn from the Harris Fire.

Within the eastern half of the fire, desert chaparral and oak woodland habitats generally burned at a moderate severity; however, there were significant areas of low severity burn, primarily throughout the southeastern half of the fire. The canyons on the northern portion of the fire including; Lake Barrett, Rattlesnake Canyon, Echo and McAlmond Mountains, and the slopes north of Tecate Peak burned at a moderate severity, while Potrero and Tecate burned with a lower severity.

Sage scrub-dependent bird species, including coastal California gnatcatcher, recover quickly from fire as the sage scrub recovers within one to five years after the fire. Areas which have recently burned may be slower to recover and have the potential to convert to non-native grasslands. Based on the low severity and patchy nature of the burn throughout the sage scrub habitat, most upland bird species, including gnatcatcher, are at a low risk of extirpation from the fire. Coastal cactus wren, a cactus/sage scrub-dependent species, however, recovers much slower. Cactus scrub must be taller then three feet to support wrens. Data from the LagunaFire of 1993 demonstrated a 58 percent decline in the wren populations, 13 years following the Laguna Fires (Mitrovich and Hamilton, 2006). Because of the long recovery period for Coastal cactus wren, and the amount of habitat lost throughout southern California in the 2007 fires, the Coastal cactus wren is at high risk of extirpation from the fire.

Two sensitive butterfly species are known to occur within the fire area. The Quino checkerspot butterfly occurs in open sage brush/chaparral habitats within the hills north and south of Otay Lakes Road and east near Barrett Junction. The exact effects of the fire on Quino checkerspot butterfly larvae are unknown, due to insufficient data; however, in areas of low to patchy burn, it is expected that some larvae survived the fire. In areas of moderate burn, the potential for survival of the larvae remain questionable. Post fire recovery in low burn areas could see a spike in population if availability of the herbaceous host plants, Dwarf plantain (Plantago erecta) or Indian paintbrush (Castilleja exserta), are abundant after the fire. Due to the species’ already limited range and the temporary loss of a significant amount of habitat, the Quino checkerspot butterfly is at high risk from extirpation from the fire.

Thorne's hairstreak is only known to occur within the Tecate cypress forests of Otay Mountain. Because the Tecate cypress is the host plant for the Thorne's hairstreak, the loss of Tecate cypress could result in a direct loss in habitat for Thorne's hairstreak. Although a major portion of the Otay Mountain Tecate cypress population was not burned in the 2007 fire, several smaller stands of mature trees along the southeastern slopes of Otay Mountain were burned. Thorne's hairstreak is at a high risk of extirpation because of its dependence on Tecate cypress as a host plant.


Reptile species including Red diamond rattlesnake and Orange-throated whiptail, and small mammal species such as the San Diego woodrat, likely sustained some mortality as a direct result of the fire; however, based on the low severity of the burn in suitable habitat, these species are at low risk from the fire.


Mountain lions, deer, and mesopredators including bobcat, coyote, and grey fox will typically survive the initial fire event. Based on the low to moderate severity of the burn, and observed evidence of wildlife, and wildlife movement throughout the burn area after the fire, large mortalities of mountain lion, deer, and mesopredators after the fire are not anticipated.

Lowland Habitats
Riparian habitats within the western half of the fire generally burned at a low severity; however, riparian areas at Sweetwater Reservoir and lower reaches of Dulzura Creek, dominated by willow species and mulefat, burned at a moderate severity. On the eastern half of the fire, the burn severity within riparian was mixed.

Larger riparian corridors of Cottonwood Creek, Dulzura Creek, and Grapevine Creek generally burned at a low severity with only patches of moderate severity, while smaller riparian systems dominated by smaller oaks (Quercus berberidifolia) burned at a moderate severity.

The state and federally listed endangered Least Bell’s vireo is a spring breeding species in willow drainages throughout the burn area. Sweetwater Reservoir is the largest population of nesting Vireo within the burn area. Because Least Bell’s vireo is a spring migrant, no direct impacts to the species occurred during the fire. Indirect impacts will occur when Least Bell’s vireo return in spring 2008 and find minimal to no suitable nesting habitat. Because the Sweetwater Reservoir is known to support a significant San Diego population of the species, the species is at high risk from the fire.

Arroyo toad, known to occur in Potrero Creek and Upper Cottonwood Creek (near Lake Barrett) and lower Cottonwood Creek (west of Marron Valley), likely survived the initial fire, but could be impacted by extensive sedimentation after the fire. Forage and breeding habitat in burn areas is likely to be significantly reduced in quality until debris/sediment flows are normalized.

 

Witch Fire

The Witch Fire started on October 21, 2007 and was fully contained ten days later on October 31, 2007. It originated in the Witch Creek Canyon near Santa Ysabel, then rapidly spread to the communities of Ramona, Rancho Bernardo, Poway, Escondido, Lake Hodges, 4S ranch, Del Dios, and Rancho Santa Fe. In total 197,990 acres burned, eventually joining the Poomacha Fire to the north (see map). Approximately 1,125 homes and 500 outbuildings were destroyed. There were 1,721 firefighters assigned to the incident under unified command. There were 40 injuries to firefighters, and two reported civilian fatalities. The estimated cost of the fire to date is $16 million.

Photo by K.C. Alfred, San Diego Union-Tribune

Home burns in Rancho Bernardo (October 22, 2007)

The fire burned through six habitat communities, including chaparral, coastal sage scrub, Oak woodland/forest, grassland, riparian, and other wetland vegetation communities (see Table 2). Aided by the Santa Ana winds it was a quick moving fire with an extremely rapid rate of spread.

Table 2:

Summary of Habitat Acres Burned

Habitat

Acres Burned

Coastal Sage Scrub

31,648

Grassland

9,148

Riparian

4,691

Other Wetlands

2,911

Chaparral

68,880

Oak Woodlands

23,741

This summary of the fire impacts presented here was based on the burned area emergency rehabilitation (BAER) team assessments immediately following the fire. This was a rapid assessment conducted by a multidisciplinary team of experts for the purpose of assessing fire impacts on 1) human life and safety, 2) property, and 3) biological and cultural resources. The BAER report in its entirety, including specific recommendations for minimizing undesirable post-fire effects, is referenced and viewable below as a pdf document.

Geology/Hydrology

The Witch Fire burn area contained numerous high to moderate risks to life and property, predominately due to debris flow, rock and tree fall, flooding and sedimentation. Residential structures constructed on or adjacent to steep slopes and in drainage channels are typical in this area of San Diego County and pose the greatest risks to life and property. Paved and unpaved roads in and below the burn area that cross drainage channels and that are the sole means of ingress and egress into burned area are common, and at risk and further threaten both life and property.

Potential Areas and Assets at Risk

Photo by K.C. Alfred, San Diego Union-Tribune, October 22, 2007

Firefighter Mike Bashem sprays water on a home on Aguacate Way in Rancho Bernardo

Vegitation and Wildlife

The burn area included plant and animal communities found in both upland and lowland habitats. Upland habitats are at higher and dryer elevations, more fire prone, and support plant and animal types that are adapted to cycles of drought. These include Coastal sage scrub, grasslands, chaparral, and oak woodlands habitats, as well as integrated habitats. Fire impacts to upland habitats are expected to be direct and recovery will depend on tolerance to fire, including for plants resprouting and regeneration (e.g., seed banks, tubers, corms, rehizomes) and, for animals, burrowing or mobility strategies. Indirect fire effects to animals species in these upland habitats are expected to be mostly a function of loss of habitat.

Lowland habitats are found at lower elevations and are that wetter, and include or more watershed drainages, such as, riparian woods and scrub habitats, freshwater marshes, and vernal pools. Lowland habitats are expected to experience indirect fire effects due to less outright fire-burned acreage. Additional indirect affects will occur, subsequently, due to runoff and erosion, with these concentrated in the downslope drainage basins.

Specific habitats affected by the Witch Fire burn included coastal sage scrub, grassland, riparian and other wetlands, chaparral, and oak woodlands/forests. Approximately 39,700 acres of the Witch Fire overlapped with areas previously burned by the 2003 Cedar Fire, and 14,500 acres overlapped with areas previously burned by 2003 Paradise Fire.

Upland Habitats

Coastal sage scrub, including cactus scrub habitats, and grassland generally burned at a low to moderate severity. Chaparral and oak woodlands/forests burned at a low to high severity.

 

Lowland Habitats

The burn was of moderate to high intensity within riparian woodland/forests and other wetland habitats. The riparian habitat along the San Dieguito River, Lake Hodges, Lake Ramona, Lake Sutherland, and Lake Poway burned at moderate to high severity. In the San Pasqual Valley, the primary concern is the burn on the right bank of the San Dieguito River that extends to Lake Hodges. Anticipated impacts include high sediment load to the San Dieguito River. Burn debris, sediment, and large woody debris will be mobilized from the Lake Hodges area. The Santa Ysabel stream reach at San Pasqual will likely have increased sediment loads and transport downstream. It is also likely that aquatic species will be affected by poor water quality resulting from mobilized debris and sediment. Due to extremely high burn severity within the Lake Ramona reservoir watershed, it is likely that there will be highly mobilized ash and sediment. Possible effects to water quality could extend to other downstream reservoirs. In general, it is likely that the extent of these burn areas will have effects to downstream aquatic biota, as well as an increase in large woody debris throughout and beyond the burn areas. Debris will most likely flow downslope into Sutherland Dam reservoir. Several trees and vegetation are intact at the bottom of the hills near the west edge of the lake.

Biological Impacts of the Fire

Cultural Resources

The 197,990-acre Witch Fire burn area includes over 1,200 archaeological sites. Some of the most significant archaeological sites within the county were situated within the burn area. The prehistoric sites include artifact isolates, artifact scatters, bedrock grinding features, hearths, middens, rock shelters, rock art, and other features associated with habitation sites. There are also areas designated as sacred places and areas of significance by the Native American Heritage Commission. The prehistoric occupation of San Diego County dates as far back as 10,000 years ago.

 

There were also several historic sites affected by the Witch Fire, including artifact isolates, artifact scatters, trash dumps, camp sites, trails and roads, structural features, as well as other artifacts and features associated with the rich cultural heritage present in San Diego County.

Rice Fire

The Rice Fire began late afternoon on October 22, 2007 in the Northwestern corner of San Diego County in and around the rural community of Fallbrook. It burned for seven more days resulting in destruction to 206 homes, 2 commercial properties, and 40 outbuildings. A total of 9,472 acres were also burned (see map). There were five injuries. Two thirds of the burn was low to moderate in severity.The estimated cost of the fire to date is $6.5 million.

Five overlapping San Diego habitats were impacted by the fire: Coastal sage scrub, grassland, riparian, chaparral, oak woodlands. This section of north San Diego County also contained large amounts of agricultural vegetation, including floricultural species, avocado, citrus, and other smaller and more specialized agricultural resources.

Photo by Scott Chester

Early stages of Rice Fire near Fallbrook (October 22, 2007)


Topography of the burn area ranged from from flat areas, to rolling hills, to canyons and mountains, with an elevation range 320-1,617 feet above sea level. Some slopes are very steep, but rarely in excess of 100 percent. The burn area contained mostly granitic and similar rock with minor metamorphic inclusions. The majority of the soils had the characteisitcs of decomposed granite.


Two major watershed systems traversed the burn area, Santa Margarita River/Sandia Canyon and San Luis Rey River. While these were largely unaffected, three tributary watersheds were adversely impacted: Rainbow Creek, Stewart Canyon, and Rice Canyon.

This summary of the fire impact was based on the burned area emergency rehabilitation (BAER) team assessments immediately following the fire. The team focused on areas of moderate and high burn severity with closely correlated potential threats to life and property. Other locations and situations were noted and recommendations made when they were observed. The BAER report in its entirety, including specific recommendations for minimizing undesirable post-fire effects, is referenced and viewable below as a pdf document.

Photo by Paul Gallaher/The Village News

Fallbrook residents evacuate westward via Ammunition Road,

through Camp Pendleton (October 222, 2007)

Vegitation and Wildlife

The Rice Fire burned rapidly at a low to moderate burn severity, with large areas left unburned within the fire perimeter. Overall for the fire event 6.9% of the 9,472 acres was rated as high burn severity, 26.0% as moderate severity, 19.8% as low severity, and 47.3% as unburned.

The Rice Fire burn area impacted five separate habitats, as summarized in Table 3 below. In addition, 3,400 acres of agricultural lands and 8 acres of Eucalyptus stands were burned. (See vegitation map of burn area)   These habitat communities support a host of wildlife and native plants, including 14 Sensitive plant and animal species.

Three primary categories of threats to wildlife and habitats within the Rice Fire burn area were identified by the BAER team as 1) direct affects of erosion, 2) excessive siltation and nutrient loads, and 3) exotic plant invasions.

Table 3:

Summary of Habitat Acres Burned

Habitat

Acres Burned

Coastal Sage Scrub

2,204

Grassland

600

Riparian

360

Other Wetlands

0

Chaparral

1,500

Oak Woodlands

400

The burn area included plant and animal communities found in both upland and lowland habitats. Upland habitats are at higher and dryer elevations, more fire prone, and support plant and animal types that are adapted to cycles of drought. These include Coastal sage scrub, grasslands, chaparral, and oak woodlands habitats, as well as integrated habitats. Fire impacts to upland habitats are expected to be direct and recovery will depend on tolerance to fire, including for plants resprouting and regeneration (e.g., seed banks, tubers, corms, rehizomes) and, for animals, burrowing or mobility strategies. Indirect fire effects to animals species in these upland habitats are expected to be mostly a function of loss of habitat.

Lowland habitats are found at lower elevations and are that wetter, and include or more watershed drainages, such as, riparian woods and scrub habitats, freshwater marshes, and vernal pools. Lowland habitats are expected to experience indirect fire effects due to less outright fire-burned acreage. Additional indirect affects will occur, subsequently, due to runoff and erosion, with these concentrated in the downslope drainage basins.

Interagency State Burned Area Response (BAER) Report (2007, November 17)

Low burn severity in Santa Margarita Canyon

Upland Habitats

A threatened species found in coastal sage scrub in the burn area was the California gnatcatcher. Other animal species of concern in the same habitat as well as chaparral, oak scrub and grassland habitats were rufous-crowned sparrow, red diamond rattlesnake, coast horned lizard,  orange-throated whiptais, California pocket mouse, and the rosy boa.

Sensitive upland plants of concern within the perimeter of the fire included the yellow pincushion, Rainbow manzanita, Orcutt’s brodiaea, and Parry’s tetrococcus.

Lowland Habitats

Residing in lowland habitats were numerous species, including the endangered least Bell’s vireo, arroyo toad, and arroyo chub. Most of the riparian habitat within and along streams burned at a lower intensity during the fure and many of these habitats will recover within 2-3 year time frame to a moderately functional level.

Ash and other sediment/high nutrient loads will likely wash into streams increasing the Total Maximum Daily Loads for total nitrogen and phosphorus, Total Dissolved Solids, and Total Suspended Solids within the water courses and will cause short term problems for water quality that could affect aquatic species. Rainbow Creek and Santa Margarita River support resident populations of arroyo chub which are California Species of Special Concern (CSC), as well as native Amphibians.  Both may be negatively impacted by excessive nutrient loads. The San Luis Rey River supports a population of arroyo toad and may be similarly impacted.

With regard to both upland and lowland habitats, many of the native plant communities within low to moderate burn areas have evolved under a fire regime and are expected to regenerate naturally within 2-3 years to a moderately functional level. Areas that burned severely are at risk of poor natural plant regeneration and may have high rates of soil erosion and invasive plant expansion.

The wildlife habitat lost in the Rice Fire, however, has caused mobile wildlife species to be displaced. As vegetation communities re-colonize, wildlife species are expected to reoccupy the burned area. Plant communities with a variety of age classes arranged in a mosaic throughout the landscape, often reflective of how previous fires burned over the landscape, should provide for continued high plant and animal diversity within the Rice Fire perimeter.

Geology/Hydrology

The Rice Fire burned rapidly at a low to moderate burn severity, with large areas left unburned within the fire perimeter. The values at risk were identified by the BAER team as 1) possible loss of life and property due to slopegenerated landslides, debris flows, rock fall, and associated slope movement and 2) degradation of drinking and agricultural water reservoirs. (Potential Areas and Assets at Risk)

In general, the risk from landslides, debris flows and rock falls were possible where roads, residences or other development awere located on alluvial fans, colluvial footslopes, and debris cones. Soil hydrophobicity was tested in several locations. For those areas of moderate and high severity burn, soil conditions were highly variable, but generally found to have high hydrophobicity increading the likelihood of flooding.

 

Poomacha Fire

The Poomacha Fire started on October 23, 2007 as a house fire on the La Jolla Indian Reservation and quickly spread through Pauma Valley to the lower slopes of Palomar Mountain, the northern slopes of Boucher Hill, and into lower Doane Valley. It burned approximately 49,410 acres and was declared contained the first week of November, 2007. A total 138 homes and 78 outbuildings and one commercial property were destroyed. This included 60 structures on the Rincon Reservation (homes, mobile homes, and other facilities) and 31 structures on the La Jolla reservation. There were 379 firefighters assigned to the incident resulting in 15 injuries. The estimated cost of the fire to date was $21 million.

Photo by George Wester (© 2007)

Poomacha Fire as seen from Temecula

The northern part of the Poomacha Fire area included part of the Palomar uplands, with elevations exceeding 5,500 feet. To the southeast were low foothills, representing over a 4,000 foot elevation differential between the uplands and lowlands. The burn perimeter also consisted of scattered parcels of private land within larger Tribal and Federal lands (see map).

This summary of the fire impacts presented here was based on the burned area emergency rehabilitation (BAER) team assessments immediately following the fire. This was a rapid assessment conducted by a multidisciplinary team of experts for the purpose of assessing fire impacts on 1) human life and safety, 2) property, and 3) biological and cultural resources. The BAER report in its entirety, including specific recommendations for minimizing undesirable post-fire effects, is referenced and viewable below as a pdf document.

Photo by Wally Skalij / Los Angeles Times

Firefighter dwarfed by flames along East Grade Road on Palomar Mountain (October 24, 2007)

 

Vegitation and Wildlife

The Poomacha Fire, aided by the strong winds, was quick moving with an extremely rapid rate of spread. Approximately 15,100 acres of the fire overlapped with the 2003 Paradise Fire burn area. Seven habitat comunities were affected, including Coastal sage scrub, chaparral, oak woodlands, mixed conifer forest, grassland, riparian, and other wetland vegetation communities (see vegitation map of burn area). Specific habitat impacts are summarized in Table 4 below.

Table 4:

Summary of Habitat Acres Burned

Habitat

Acres Burned

Coastal Sage Scrub

6,197

Grassland

3,138

Riparian

823

Other Wetlands

196

Chaparral

15,958

Oak Woodlands

9,148

Mixed conifer forest
11.503

The burn area included plant and animal communities found in both upland and lowland habitats. Upland habitats are at higher and dryer elevations, more fire prone, and support plant and animal types that are adapted to cycles of drought. These include Coastal sage scrub, grasslands, chaparral, and oak woodlands, and mixed conifer forest habitats, as well as integrated (i.e. overlapping) habitats. Fire impacts to upland habitats are expected to be direct and recovery will depend on tolerance to fire, including for plants resprouting and regeneration (e.g., seed banks, tubers, corms, rehizomes) and, for animals, burrowing or mobility strategies. Indirect fire effects to animals species in these upland habitats are expected to be mostly a function of loss of habitat.

Lowland habitats are found at lower elevations and are that wetter, and include or more watershed drainages, such as, riparian woods and scrub habitats, freshwater marshes, and vernal pools. Lowland habitats are expected to experience indirect fire effects due to less outright fire-burned acreage. Additional indirect affects will occur, subsequently, due to runoff and erosion, with these concentrated in the downslope drainage basins. Species of special  interest in the burn area included:

Sage scrub/chaparral species
• Coastal California gnatcatcher

Grassland species

• Golden eagle

Mixed conifer forest species

Nevin’s barberry

Dunn’s mariposa lily

Laguna Mountains skipper butterfly

Large-blotched salamander

Riparian Species
• Arroyo toad
• Southwestern willow flycatcher

Biological Impacts of the Fire

Geology/Hydrology

The Poomacha Fire burn area contained a small number of high to moderate risks to life and property, predominately due to flood, hyperconcentrated flood, debristorrent, debris flow, rock fall, rock slide and tree fall. Residential structures built on or adjacent to steep slopes and drainage areas posed the greatest risk to life. Paved and unpaved roads in and below the burn area, that cross drainage channels and that are the sole means of ingress and egress were common, and to the extent they are at risk  threaten both life and property. Utility lines in specific areas appeared to be at risk and merited additional
evaluation.

With the Poomacha Fire a major post-fire concern was with steep slope debris flow and and flooding on parts of Palomar Mountain, debris flow in the Lake Sutherland area, and flooding near homes on the Mesa Grande Indian Reservation near Scholder Creek.

Potential Areas and Assets at Risk

 

Photo by John Gastaldo/San Diego Union-Tribune

An S2T air tanker makes a drop on the northeast side of Palomar Mountain (October 24, 2007)

 

Cultural Resources

The Witch/Poomacha Fire burned in a diverse heritage resource area including historic and pre-historic sites. At least 67 recorded sites are located within and/or adjacent to the burn areas. Ten of the sites were located within areas of moderate to high soil burn severity. Seven sites were evaluated. It was determined that there was not an emergency situation with regards to heritage resources for the Witch/Poomacha Fires.

Photo by Wally Skalij / Los Angeles Times

Firefighters hose down hotspots on Palomar Mountain

(October 24, 2007)

 

Sources:

Interagency State Burned Area Response (BAER) Report. (2007, November 17). Rice Fire

Interagency State Burned Area Response (BAER) Report. (2007, November 17). The Poomacha Fire

Interagency State Burned Area Response (BAER) Report. (2007, November 20). Harris Fire (CA-MVU-010427).

Interagency State Burned Area Response (BAER) Report. (2007, November 17). The Witch Fire.

USDA Forest Service Burned-Area Report. (2007, November 19). Harris Fire (FSH 2509.13).

USDA Forest Service Burned-Area Report. (2007, November 21). Poomacha Witch Fires (FSH 2509.13).

Photo Credits:

Alfred, K.C. (2007). Select photographs of Witch Fire. San Diego Union-Tribune. Retrieved December 2, 2007 from SignOnSanDiego http://signonsandiego.lamphost.net/northcounty?page=17

Alfred, K.C. (2007). Select photographs of Harris Fire. San Diego Union-Tribune. Retrieved December 2, 2007 from SignOnSanDiego http://signonsandiego.lamphost.net/southcounty?page=1

Cepeda, N. (2007). Select photographs of Harris Fire. San Diego Union-Tribune. Retrieved December 4, 2007 from

Chester, S. (2007). Photograph of Rice Fire. Retrieved December 4, 2007 from Facebook http://www.facebook.com/album.php?aid=2039476&page=1&l=f7721&id=19902680

Gallaher, P. (2007). Select photograph of Rice Fire. The Village News. Retrieved Decemebr 9, 2007 from http://www.palagems.com/fallbrook_fire.htm

Gastaldo, J. (2007). Select photograph of Poomacha Fire. San Diego Union-Tribune. Retrieved December 2, 2007 from http://signonsandiego.lamphost.net/northcounty/GAS_palomar278919x015

Gibbins, J. (2007). Select photographs of Harris Fire. San Diego Union-Tribune. Retrieved December 2, 2007 from http://signonsandiego.lamphost.net/southcounty?page=2

Lewis, N.E. (2007). Select photograph of Harris Fire. San Diego Union-Tribune. Retrieved Decemebr 2, 2007 from http://signonsandiego.lamphost.net/southcounty

McVeigh, J. (2007). Select phtotgrapgh of Harris Fire. Los Angeles Times. Retrieved December 7, 2007 from 

Skalij, W. (2007). Select Photographs of the Poomacha Fire. Los Angeles Times. Retrived December 6, 2007 from http://www.latimes.com/news/local/la-me-tictoc24oct24,0,449513.story?coll=la-home-center

Wester, G. (2007). Select photogrph of Poomacha Fire. Flickr, Retrieved December 6, 2007 from http://www.flickr.com/photos/gwester/1722638136/

References:

County of San Diego. (2007, October). Vegetation and Conserved Lands Affected by the Witch Creek,
Harris, and Poomacha Fires
. San Diego: Author.

 

 

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