Drinking-Water Wells May Contain Chemical Contaminant. More than 300 drinking-water wells in the San Martin area may be contaminated with a chemical, used in the manufacturing of rocket fuel and highway flares, that could cause health hazards for pregnant women and infants.
The chemical, perchlorate, has spread in a four-mile underground plume and could affect drinking-water supplies for more than 2,000 people, officials said. Residents are being urged not to drink the water until it’s been tested by the water district.
Perchlorate has been detected in 12 of 100 wells tested in the unincorporated area between Gilroy and Morgan Hill. One municipal well in Morgan Hill has been closed because of the contamination. Santa Clara Valley Water District officials said Thursday that an additional 350 wells must be tested.
County and state water and health officials announced the findings Thursday at a news conference at the Santa Clara Valley Water District headquarters in San Jose. Once the extent of the problem is determined, systems must be designed to pump out and treat the contaminated water.
“We now believe that as many as 450 private wells in South Santa Clara County could potentially have low levels of the chemical perchlorate,” said Walt Wadlow, the water district’s chief operating officer.
The area of concern is bounded by Tennant Avenue on the north, Center Avenue on the east, Monterey Highway on the west and Masten Avenue on the south, Wadlow said.
Perchlorate is a salt, artificial as well as naturally occurring. It primarily is used as an oxidizer for rocket fuel, highway safety flares, matches, fireworks and other products.
Perchlorate, which is considered to have adverse health effects, disrupts iodine intake in the thyroid gland, which regulates hormone functions. Some studies suggest it may be a cause of thyroid cancer.
Pregnant And Infants Are At Higher Risk
Pregnant women and infants are at the highest risk because perchlorate may impair neurological development in fetuses, said Dr. Martin Fenstersheib, Santa Clara County’s public health officer.
Contaminated water should not be used for drinking or cooking, although bathing should pose no hazard, Fenstersheib said. Boiling water only concentrates the perchlorate in food being cooked.
Fenstersheib said it will take extensive research to determine whether there is a concentration of people with thyroid disease in the affected area. “Thyroid illness is not a reportable disease,” he said. “It has not been seen yet in hospital data. You have to go out and look for it.”
There are no federal or state safe drinking-water standards or maximum allowable contaminant levels for perchlorate. However, the state Department of Health Services has set four ppb (parts per billion) as the level at which action must be taken to resolve the problem.
A law authored by state Sen. Byron Sher, D-Palo Alto, requires the state to adopt a standard by Jan. 1, and the state Office of Environmental Health Hazard Assessment has proposed a public health goal of six ppb.
Concentrations in the South County wells ranged from four ppb to 98 ppb, Wadlow said.
In Southern California, much of the lower Colorado River has been polluted by perchlorate and hundreds of wells have been shut down. In Redlands, east of Los Angeles, more than 1,000 people are suing Lockheed Martin Corp. over pollution at a former rocket engine-testing facility.
The chemical was first discovered in the area more than two years ago at a 13-acre site near the intersection of Tennant and Railroad avenues in southern Morgan Hill where Olin Corp. operated a flare-manufacturing plant from 1955 to 1996. The company mixed chemicals in metal bowls, which were then washed out. The rinse water was dumped into an evaporation pond, from which it percolated into the ground, said Harvey Packard, a resource engineer for the Central Coast Regional Water Quality Control Board, the state agency leading the investigation.
Olin cleared the property and put it up for sale in 1997. An environmental analysis at the time didn’t raise any red flags because perchlorate was not yet identified by scientists as a possible health hazard.
In 2000, a potential buyer did another study and found perchlorate. The chemical by then had been listed as an environmental hazard in groundwater.
Last March, perchlorate was found in a Morgan Hill municipal well 250 feet from the Olin site. The city immediately closed the well and now is drilling a replacement, with costs paid by Olin.
That discovery triggered the regional water board and the valley water district to sample more wells off the Olin site, which turned up the contamination that officials disclosed on Thursday.
“We have to drill more borings to isolate the source and clean it up,” said Packard, of the regional water board. “It will take a long time to clean up.”
Packard said a long-term solution may even be replacing the contaminated water sources.
Home filtration systems do not remove this chemical.
Pastor Drake Fenn of the Family Worship Center in San Martin said he met with Olin representatives Tuesday. “They’re very cooperative. We’re going to help them notify families,” said Fenn. “Our head and heart in this matter is to keep calm and take things logically.”