Debris-Flows & Mudslides

	After the Fire Information What dangers did the fire create ? Which areas are at risk ? How can you be aware of adverse weather conditions ? How does the NOAA weather radio receiver operate ? How do the rain gauges work ? Will I be safe driving these roads ? Severity & Debris Flow Potential Chart
OEM Brochure	FLOOD INSURANCE IS IMPORTANT	Haflin Creek after small rainstorm

What dangers did the fire create ?

On June 9, 2002 the Missionary Ridge Fire started near a forest access road on the east side of the Animas Valley approximately 12 miles north of Durango. Within the first day, the fire left the valley floor and grew to 6,500 acres as it burned eastward up the Coon Creek drainage to the top of Missionary Ridge. The extreme drought conditions which were prevalent throughout Southwest Colorado allowed the fire to eventually form a fire perimeter of 112.2 miles with an interior acreage of 70,485 acres of private, State and Federal lands. Consuming over a thousand acres an hour the first day, the fire would burn for the next 36 days and move eastward through numerous tributaries to four separate river drainages.

Fire officials indicate this type of fire only occurs once every 100 to 200 years. Put in a different perspective, only once in 100 to 200 years does an extreme drought sufficiently dry all vegetation and fuels in the forest to a point a large devastating fire can occur like the Missionary Ridge Fire. All forms of vegetation from trees, to scrubs, to the duff or litter layer on the forest floor burned with such intensity and severity that all that remained after the fire was standing trunks of larger trees and varying depths of powder ash on burned ground. Thirty-one percent or 22,542 acres burned with high severity which resulted in 75 - 100% of all trees and shrubs burned along with 90 - 100% of ground litter. Moderate burn occurred on 30% or 21,822 acres of the total fire area. In the moderate burn area 25 - 75% of evergreen/conifer destroyed with 50 - 75% of aspen and oak destroyed. Combined, 44,364 acres of the 70,485 acre total have now been burned to a point that storm water and spring snow melt runoff characteristics have been severely altered.

Further altering the runoff is a phenomenon known as “Hydrophobic soil condition.” This is a process of the fire which makes the soil repel water and prevents water from seeping into the dirt. Much of the severely burned area is on very steep slopes in the mid to upper elevations of canyons and drainages above private lands. Steep slopes with no vegetation or duff + exposed erodible soils and rocks + water repellent soils + large drainage areas covered with ash and debris points to the potential for catastrophic floods when moderate to heavy rains fall in those canyons and drainage basins. Moderate rains in July, August and September of 2002 moved large volumes of the ash cover from much of the fire area. That initial flush of ash filled streams and rivers with ash and debris, which adversely effected municipal water supplies for Durango, Bayfield, Ignacio and the Southern Ute Indian Tribe. Several private domestic water supplies for subdivisions and private property owners were also damaged.

As time passes, some portions of the burn area will witness regrowth of vegetation faster than other areas. On steep slopes where heavy stands of evergreen trees once stood, regrowth will be very slow. These areas will be prone to heavy erosion and increased water runoff for several years. Other areas where quaking aspen, oak brush and various species of shrubs grew will experience rapid regrowth as those species sprout new growth from the existing root systems. Evergreen or conifer species must sprout from natural reseeding processes. With no vegetation or duff layer on the ground, there is no means to slow water runoff. The increased storm runoff or snow melt is free to flow down the steep slopes and wash soils, rocks and other debris into water courses, which in turn flow into other ravines and canyons.

In almost all cases, these ravines and canyons flow downslope onto private lands and county roads before those flows enter river systems. The fire has altered some areas and drainages so significantly property owners and county road traffic will be troubled with flooding and debris each time a moderate to heavy rain storm occurs. Large rain storms that produce heavy downpours in short periods of time will prove to be extremely dangerous and could produce heavy flooding affecting homes situated next to streams or on debris fans at the mouths of canyons. All individuals living near the fire perimeter or driving county roads should always be mindful of changing weather conditions and the threat of potential flooding when rainstorms enter the burn area.

Which areas are at risk ?

In a 40 mile distance of County Roads 250, 252, 240, 243, 501 and 501-A there are 24 significant named canyon drainages which cross those roads. Each one of the canyon drainages and numerous unnamed drainage areas have all been affected by the fire. Some canyons (with several tributaries to each canyon) have experienced high burn severity over large areas which will increase storm runoff.

How can you be aware of adverse weather conditions?

In the early part of 2002, a local consortium of agencies banded together to sponsor and fund a NOAA all hazards weather radio transmitter which broadcasts weather and civil emergency information to the citizens of La Plata County and portions of surrounding counties. This radio transmitter is situated on the top of Missionary Ridge near a group of public safety radio transmitters. The transmitter broadcasts weather information specific to La Plata County - 24 hours a day. Weather information is provided by the Grand Junction office of the National Weather Service. All citizens in La Plata County should purchase a weather radio receiver for their home. In addition to receiving constant weather information, radios with the SAME (Special Area Message Encoding) will be able to receive a special signal from the weather service that activates an alarm in the home receiver to announce special adverse weather broadcasts and/or information on other civil emergencies.

The La Plata County Sheriff’s Department in coordination with the Office of Emergency Management will be able to cooperate with the Grand Junction Weather Service to activate the home radio alarms to provide specific information to residents who live or drive near the fire perimeter and could be affected by storms and flooding.

Transmit Frequency of 162.425 SAME Code 08067 (FIPS)

How does the NOAA radio receiver operate?

When the radios are purchased, they can be placed in homes or in a vehicle (with battery power) and set to the “monitor” setting. The radio sits quietly “monitoring” the frequency. When local law enforcement or emergency management officials observe dangerous storms or other civil emergencies, they can request the Grand Junction Weather Service to activate the alarm process to provide specific messages. When activated, radios with the “SAME” feature will alarm citizens with an audio alert tone and relevant message. For many people that live or drive along the fire perimeter this radio alert capability will be able to provide warning information which could provide those individuals with valuable time to leave the flood prone areas or prepare for the adverse weather effects.

One homeowner explained the weather radio and alert function would help him and his family sleep better at night. “Knowing that the alert system will alarm when adverse weather develops over the burn area gives us some comfort. When we hear the alert tone we will be able to leave our home before the roads are blocked by debris” he explained. The greatest risk to residents in the fires flood prone areas is heavy rains that fall during the night when no one can see the cloud build up. Periodically isolated heavy thunder storms produce heavy down pours in narrow bands or concentrated areas. When these storms occur at night observers cannot see the heavy precipitation falling in a particular area. The first warning of flooding may be a wall of water and debris moving down a drainage.

How do the rain gauges work ?

Recognizing the extreme flood potential members of Federal Burn Area Emergency Rehabilitation Team (BAER) urgently requested the U.S. Geological Survey install a series of rain gauges to monitor rain fall in the burn area. These rain gauges are positioned in 12 strategic locations and are linked to satellites which receive precipitation information and then send that information to ground stations. The National Weather Service Office in Grand Junction receives that “real time” information and compares the rain fall to radar images of storms over the burn area. Significant increases in precipitation recorded by the rain gauges and/or radar reading showing high potential of heavy rain will prompt weather warnings on the local weather radio.

During previous storms some drivers attempted to drive through the debris and became stranded and venerable to increased flows. During heavy rains flood waters may flow from smaller drainage areas and effect sections of roads that have not been identified by the hazard signs. If heavy rains occur avoid the hazard zones and be prepared to seek safety in areas which have no flood debris or water. When flooding and debris effect the roads heavy equipment will be maneuvering on the roads to remove debris - stay clear of that equipment. Additional warning and road signs with flashing lights will provide motorists with additional information relevant to flood watches and flood warnings with road closures.

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