Montecito Water District Corrects Facts on January 9 Debris Flow Incidents
(March 7, 2018 - Montecito, California)
Since the debris flow that occurred on January 9th, widespread reporting of inaccurate information has occurred. In advance of last week’s rain, Montecito Water District (MWD) responded to numerous customer inquiries about the functionality and condition of District infrastructure. The District provides this press release in an effort to alleviate concerns and disseminate accurate information.
Matrix of Fact Corrections
Erroneous reports included mention of damage to the South Coast Conduit, damage to District storage reservoirs, remote valve operation failures, and more.
|MWD’s storage reservoirs were ruptured.||There was no damage to MWD’s storage tanks (reservoirs) or treatment facilities during the storm.|
|8 to 9 million gallons of water drained downhill from MWD reservoirs.||Seven storage tanks containing a total of 5.8 million gallons of water drained slowly, over the course of 11 hours, through more than 300 geographically disbursed ruptures in the system. These leaks were caused by debris impacts to infrastructure on January 9th. Illustrative photos of pipeline breaks can be found on MWD’s website in the presentation from the February 1, 2018, Board Meeting: www.montecitowater.com|
|Remote shutoff for valve system failed due to power outage.||There is no remote shutoff system. Valves are manual. The power outage had no impact on this. Water distribution would not have been shut off prior to or during the event, as water is necessary for public health and safety, fire protection, etc.|
|Employees did not have access to generators.||See above. Critical District staff sheltered in place during the storm, and crews were on site by 6 a.m. on January 9th, inspecting damage, shutting down leaks, and making repairs.|
|“Highline” refers to a high-pressure line.||The District has a transmission pipeline that appears on maps to run high along the hills and over the years it has come to be called the “Highline” for ease of reference. This is a 14-inch diameter pipe that conveys water to the distribution system pressurized as low as 40 psi and up to 150 psi. It is sited below the origin of the debris flows, which were initiated by rainfall intensity in the highest mountain elevations of the watersheds. The transmission pipeline was ruptured and drained slowly at nine separate locations where it was clearly impacted by boulders or attached to bridges that were damaged and/or destroyed.|
|MWD’s water loss occurred instantly at a single location.||The loss was gradual and spread across a geographically wide area and across more than 300 leaks in the District’s distribution system through nine transmission pipeline breaks, 15 distribution main breaks, 25 sheared off fire hydrants, and approximately 290 damaged service connections.|
|The South Coast Conduit was damaged in the storm.||While this was a concern early on and assessment was required, it was confirmed on January 11th that there was no damage to the South Coast Conduit delivery system which is operated by the Cachuma Operations and Management Board (COMB).|
In the early hours of January 9th, Montecito experienced a storm of near record-setting intensity. Depending on the data source – National Weather Service, County of Santa Barbara or the National Oceanic Atmospheric Administration – rainfall met or exceeded a 200-year storm standard, dropping more than 0.5 inches in 5 minutes and 0.75 inches in 15 minutes. The rainfall was of extremely high intensity and short duration, resulting in significant amounts of runoff in the watersheds above Montecito.
Natural watersheds that feed the creeks that flow through Montecito cover over 11,000 acres and are of steep terrain, ranging from an elevation of 0 feet at the beach to approximately 3,600 feet at East Camino Cielo. The storm’s impact was intensified because the Thomas Fire in December burned these watersheds extensively. The Thomas Fire, the largest in California history, stripped the vegetation from mountainous hillsides, leaving little or no earth-binding root structures in place, and reduced the water-absorbing properties of the soil. Preliminary analysis indicates that nearly 200 million gallons of rainfall accumulated within the watershed during the first 15 minutes of the storm. In addition, the peak rainfall runoff intensity within the watershed has been estimated to have exceeded 14 million gallons per minute.
The high intensity rainfall caused mud and debris flows at the highest elevations in the watershed which accumulated while traveling downhill. This caused devastation within and throughout Montecito, including damage to District infrastructure. Water, mud, and debris overflowed debris basins and continued downstream, causing damage to the District’s transmission pipeline (“highline”) at multiple locations. Damage occurred at numerous creek crossings, including San Ysidro, Cold Spring, Hot Springs, Buena Vista, Romero, and Toro Canyon. Overall, District infrastructure was damaged in more than 300 locations, resulting in leaks through which a gradual loss of water occurred.
Review of MWD system data confirms that the District had approximately 5.8 million gallons of water stored in seven water storage tanks at the start of the storm on January 9th. The 5.8 million gallons of water was lost over the course of 11 hours, between 3 a.m. and 2 p.m. The loss was gradual, and leakage was spread over a geographically wide area and across the District’s distribution system through nine transmission pipeline breaks, 15 distribution main breaks, 25 sheared off fire hydrants, and approximately 290 damaged service connections; in total there were more than 300 leaks.
As compared to the peak rainfall intensity of 14 million gallons per minute, the District’s peak combined release rate was a mere 24,000 gallons per minute – less than one quarter of one percent (<0.25%) of the estimated peak rainfall intensity that fell during the storm. At the time of the first reports of destruction at 3:57 a.m., the total accumulation of rainfall is estimated at nearly 200 million gallons, while approximately 300,000 gallons is estimated to have been lost from the District’s water system by that time, again less than one quarter of one percent (<0.25%) of the rainfall figures. To put this amount in perspective, 300,000 gallons is a bit less than half the total volume of an Olympic size swimming pool.
Critical District staff sheltered in place during the storm, and crews were on site by 6 a.m. January 9th, inspecting for damage, shutting down leaks, and making repairs. While District access was prohibited in some areas due to rescue operations and debris, staff worked rapidly to organize a large team to assist and was able to secure needed materials without delay. Within 30 days of the event, the District had restored full water service to the Montecito community, including all work to access, repair and disinfect its heavily damaged facilities. These facts are provided by the District to help facilitate customer understanding of the storm’s impacts. As the community continues to be restored, MWD is here to help.Photo Credit: Montecito Water District. Photo Credit: Montecito Water District. Photo Credit: Montecito Water District. Photo Credit: Montecito Water District. Photo Credit: Interactive Map by ZWORLD GIS
Montecito Water District's mission is to provide an adequate and reliable supply of high quality water to the residents of Montecito and Summerland, at the most reasonable cost. In carrying out this mission, the District places particular emphasis on providing outstanding customer service, conducting its operations in an environmentally sensitive manner, and working cooperatively with other agencies. For additional information visit www.montecitowater.com, like Montecito Water District on Facebook, and follow on twitter @MontecitoWater.