By Mark Waite
Think this tranquil valley is immune to natural disaster?
A Nye County hazard mitigation plan being submitted to the Federal Emergency Management Agency outlines such fun facts like the chances of an earthquake striking Pahrump, the possibility of catastrophic flooding and subsidence.
Then there’s the potential for infectious diseases — a local death in 2005 due to the West Nile Virus and another from the swine flu make clear residents are anything but immune.
The only thing many Nye County residents may have had concerns about in the past was the transportation of nuclear waste to Yucca Mountain.
Nye County ranks at a high danger of wildland fires and drought. Floods, wind storms, earthquakes, winter storms and terrorist attacks are ranked a medium threat to the county.
The plan is an update to a 2005 version, according to Nye County Emergency Services Director Vance Payne. By preparing the plan, Nye County is able to qualify for presidentially declared disasters, should one occur.
The plan, prepared by Dyer Engineering Consultants Inc., gives Pahrump a 30 to 40 percent probability of experiencing an earthquake greater than 5.0 on the Richter scale, according to data from the University of Nevada, Reno, Bureau of Mines and Geology; chances rise to 70 to 80 percent for Tonopah and Beatty, and 90 percent probability for Gabbs.
Nevada has 270 known normal slip faults, with several relatively small faults in Nye County still capable of delivering earthquakes of magnitude 6 to 7 on the Richter scale.
There is a 60-mile Pahrump Valley fault, in the south, with a potential to deliver a 6.9 to 7.2 magnitude quake, as well as the 71-mile Death Valley fault, and the 111-mile Furnace Creek fault, which the study notes pose equally seismic hazards to Nye County.
The 5.6 magnitude Little Skull Mountain earthquake occurred on the National Nuclear Security Site on June 29, 1992, thought to have been triggered by the Landers, California earthquake a day earlier. On Aug. 1, 1999, a 5.7 magnitude earthquake occurred near Scotty’s Junction. The plan notes repeated, clustered, low magnitude earthquakes are often recorded along the Rock Valley fault zone at the NNSS.
While a 5.0 magnitude quake was described as a 100-year event, the plan notes it could affect 22 percent of the county’s population, or 7,100 people and damage up to 2,934 residences at a cost of $241.3 million within high or moderate ground-shaking zones.
Land subsidence has been documented, with four large fissures approximately a mile long, to the south and southeast of Pahrump. Subsidence of one inch to 18 inches was noted at 14 U.S. Geological Survey monument markers from 1981 to 2004, data from interferometric, synthetic aperture radar InSAR suggest a maximum subsidence rate in the near future of one and a half to two inches per year.
The report notes: “Because there is no source of artificial recharge for the Pahrump Valley aquifer, this problem may become more severe if overdrafting as a practice continues or grows.”
Then there’s communicable diseases. The West Nile Virus caused an epidemic that grew from an initial outbreak of 62 cases nationwide in 1999 to 4,156 reported cases, including 284 deaths, in 2002. An outbreak in Nye County in spring 2005 led to a mosquito vector program. One death due to West Nile virus was reported in Nye County that year, according to the report.
West Nile virus staged a comeback this year; 3,142 cases have been reported nationwide as of Tuesday with 134 deaths. Two-thirds of these have occurred in seven states: Texas, Mississippi, Michigan, South Dakota, Louisiana, Oklahoma and California.
From 2009-2010, the H1N1 or swine flu became a global pandemic, even reaching remote Nevada, leading to 40 deaths in this state and one death in Nye County in 2009, the plan reported.
“Both are very much under-reported,” said Martha Franstead, a spokesman for the Nevada Health Division of the two diseases.
There were actually two Nye County deaths believed linked to the swine flu in 2009, but Franstead said in one case the cause of death wasn’t clearly specified. When it comes to the West Nile virus, she said unfortunately funding has been cut for mosquito abatement programs, but so far this year, only one reported case of the illness was reported in Clark County and another in Churchill County.
In 2011, there was a significant outbreak of whooping cough in Nye County.
Africanized honey bees are mainly in southern Nye County, where they can survive the winter, but the plan states they remain a concern.
Payne said the updated plan includes information about the oil industry in Railroad Valley; it mentions the possibility of a spill or hazardous incidents not only in Railroad Valley, but in transporting the oil. The plan notes there have been 47 oil and chemical spills in the county since 1999, over half occurred at the facility.
No nuclear tests have been conducted at the Nevada National Security Site, formerly the Nevada Test Site, since 1992, but the plan notes, “the site remains one of the most radioactively contaminated places in the U.S. due to the number of tests conducted there.” That included 100 atmospheric and 828 underground nuclear detonations. The 2004 Nye County Water Plan by former hydrologist, the late Tom Buqo, estimated 5 million acre feet of water has been contaminated at the NNSS.
Thirty-nine facilities in Nye County are regulated by the U.S. Environmental Protection Agency to handle hazardous waste, but the plan notes, “in general these facilities do not pose a significant risk to the county.”
There are numerous examples in Nye County where well-defined washes routinely channel flash flood waters, the report notes, like Wheeler Wash in Pahrump and Forty Mile Wash in Amargosa Valley. The plan suggests the construction of retention basins at places like Wheeler Wash, which drains 78.6 square miles, Carpenter Canyon and in Crystal.
A state of emergency was declared in Pahrump after two days of heavy rain on Sept. 2-3, 1997 caused numerous road closures and resulted in property damages estimated at $2.7 million. Hurricane Nora reached southern Nevada later that month, cutting off access to some outlying homes in Pahrump. A storm on Sept. 21, 2007 dumped 2.7 inches of rain and washed out several roads. The latest flooding was on Dec. 22, 2010 that closed off parts of Blagg Road.
The risk posed by a 100-year flood event is moderate, the report notes, affecting 8 percent of the Pahrump Valley population, with 1,378 homes having exposure to the 100-year floodplain.
The latest Federal Emergency Management Agency flood maps will be presented at an open house from 1 p.m. to 3 p.m. and 6 p.m. to 8 p.m. Thursday at commissioner’s chambers.
Understandably, the risk of wildfires is rated moderate to extreme in forested, mountainous communities of northern Nye County like Belmont, Manhattan and Ione, but low in Pahrump, Beatty and Amargosa Valley.
The study includes a statistic of 111 severe windstorms reported in Nye County by the National Data Center between 1994 and 2011.
The major disruption to infrastructure in Pahrump occurred in January, 2007, when the area experienced a 28-hour power outage after a vandal had shot the main Valley Electric Association power line between Sandy Valley and Goodsprings.
Abandoned mining operations create hazards, like discoveries of explosive caches. A boy was lost for 19 hours in a shaft of the old Mizpah mine near Tonopah in March 1990; in another instance, an 11-year-old girl died after falling 130 feet down a mineshaft near Beatty in October 1999. Out of 2,036 abandoned mine sites in Nye County, only 1,351 have been secured, according to the Nevada Division of Minerals.
The plan states there are 52 registered dams in Nye County, mostly for tailings and potentially hazardous materials used in mining operations, but the report states they don’t pose any potential for inundating homes.
The study doesn’t mention concerns over terrorism at the NNSS, only the proximity of Pahrump to Las Vegas, which would cause Clark County residents to seek refuge in neighboring counties in the event of a terrorist attack.