A "boil water advisory" issued by the New Mexico Environment's Drinking Water Bureau on Friday, July 16, for the Socorro Water System was lifted Monday afternoon.

NMED issued the boil water advisory after E. coli was found in a water source — which, according to the report, can indicate that the water may have been in contact with sewage or animal waste. Although some strains of E. coli are harmless and live in the intestines of healthy humans and animals, other strains are dangerous the report indicated.

Mayor Ravi Bhasker said the E. coli detected was found in the source water, or water from Sedillo Springs prior to the water being disinfected and distributed to city residents.

"At no time was there fecal coliform in the city water," Bhasker said. "Only in the source water."

Bhasker said according to the NMED guidelines, a boil water advisory had to be issued to make sure the city water did not contain E. coli.

Wastewater Superintendent Dixie Daniels said it was during a routine sampling that the department conducts on a monthly basis, at random places throughout the city, that a positive test for coliform bacteria from a home on Granada Street was found.

That sample was taken Tuesday, July 13, Daniels said, but since results take 24 hours to complete it was late afternoon on Wednesday, July 14, that the NMED called to alert her that the sample came back positive for coliform bacteria, but negative for E. coli.

"That triggers re-sampling," Daniels explained of the test. "Within 24 hours, we have to re-sample, sample upstream and downstream (from where the positive test for coliform was detected) so we can isolate it."

Another thing required of the city that came into effect in December 2009, is called the groundwater rule that requires a sampling of the water source prior to any treatment or disinfection being conducted. What that means is water from Sedillo Springs was tested, but the test was made on untreated water before it is stored and treated in the Evergreen water storage tank.

Daniels said eight samples were then taken Thursday, July 15, and at approximately 4:45 p.m. on Friday, July 16, NMED called to say the samples taken upstream and downstream from the original source was absent of total coliform. However, the water source, or Sedillo Springs, came back positive for total coliform and E. coli.

"That threw the city into a boil water alert," Daniels said.

Alerting the Public

Daniels said a boil water advisory was then issued by the NMED and the public was notified of the advisory on Friday.

"We went door-to-door, took pamphlets to Tech, to the police department to distribute, to parks and we attempted to distribute notices at Walmart," Daniels said. "Mr. (Peter) Romero was at the Plaza handing out notices, too."

The media was also informed.

Daniels said of the approximate 3,300 residents on city water, between 600 and 700 homes are serviced by the Evergreen tank and those were the residents that were notified.

Daniels also said they took calls from 6 a.m. to 10 p.m., over the weekend to answer any questions citizens had regarding the advisory.

Mario Gonzales, of the New Mexico Rural Water Association, also arrived in Socorro on Saturday, to go through the city's water system.

"I informed him what we were doing," Daniels said of how water is treated. "He was here to see if we had any equipment breakdowns."

Gonzales said in a July 20 phone interview, that his office was contacted by the NMED to provide technical assistance to the city. Gonzales said he evaluated the situation, measured the flow of spring water coming into the reservoir and the Evergreen storage, calculated the contact time and measured the pH temperature.

"Everything checked out great as far as the water being treated properly and they (Wastewater Department) had good records," Gonzales said.

Monitoring levels

The wastewater department is also taking chlorine readings every 3-1/2 hours, 24/7, Daniels said. And, she said, they intend to update equipment to prevent this type of thing from happening again.

"A scare like this won't happen again," Daniels said of the boil water advisory. "We will make changes so we will qualify for a 4-Log disinfection that guarantees 99.99 percent disinfection."

What this will require will be equipment to be purchased and installed on water distribution systems that measure chlorine residuals. A data logger will monitor levels and an emergency auto dialer will send a notification if there is a drop in levels.

"We will know immediately if something changes," Daniels said.

Gonzales explained there are two systems: the trigger response and the 4-Log Treatment. He said one is not better than the other but sometimes it takes something to happen for a municipality to look at the system they are using and decide if they want to try the other route.

Right now, the City of Socorro is on a trigger response system, which is why the source water had to be tested prior to treatment.

With the new equipment in place, should a test come back positive for coliform, testing of water sources prior to chlorination will not have to be conducted. But, re-sampling the origin as well as upstream and downstream testing will have to be done. If testing comes out negative, Gonzales said you are done at that point.

"The state was pleased with everything the city did," Gonzales said."I don't think the public was in harm's way because of the treatment. They did everything by the book."

Following the Process

Although E. coli was not detected in the city's water system, Bhasker said the environmental department was correct on how they proceeded, and had the city not met the NMED's criteria, the boil water advisory would still be in effect.

"The public was never at risk," Bhasker said. "But the environment department was correct in how they proceeded on the side of caution. If we hadn't met their criteria we would have had to continue to boil water."

Daniels said the equipment they will purchase has to be approved by NMED, but her department is already preparing for it so that when it does come in, all they will have to do is plug it in.

Daniels said they will take more samples on Tuesday, July 20, in the area serviced by the Evergreen storage tank as well as in other parts of the city.

"We want to provide the safest drinking water as possible," she said. "It's not required by NMED but for the public's confidence we need to run more samples."

The Socorro Water system has five sources of drinking water. Only one source, Sedillo Springs, tested positive for E. coli prior to the water being treated and disinfected.

Contact Jackie Schlotfeldt