Las Cruces Utilities Opens New Lab to Refresh Water Quality Testing

Sep 9, 2019

In a region as thirsty as southern New Mexico, every gallon counts. To ensure drinking water stays safe and wastewater is treated properly, Las Cruces Utilities unveiled its new Water Quality Laboratory located on West Amador Avenue.

Utility officials say the roughly $4 million facility is about five times larger than the City’s existing test site and is designed to meet green building ratings.

Water Quality Lab Manager Luis Guerra has worked for the City for more than a dozen years. He said the extra space allows the lab to keep meeting safety standards and run more tests if needed.

The facility has separate labs for water and wastewater, which Guerra said helps prevent issues like cross-contamination. He demonstrated how the lab analyzes drinking water using a container filled with residential water.

Guerra said technicians collect samples at homes served by the City more than 100 times a month.

“They’ll knock on your door, you know, ask if they can sample your water and go to a spicket or go to your faucet and get a sample just like this," Guerra said.

Federal regulations require the utility to test for dozens of contaminants like copper, lead and arsenic that could potentially seep into groundwater. In addition to testing pH and nitrogen content, Guerra said the lab checks for harmful bacteria like E. Coli. To do that, technicians use a special powder.

“We bring the samples in here and what we do is we add a special media, it’s called Colilert. Put it in here, it’s food for the micro bacteria, swish it around for a while, and then we put it an incubator right here and allow it to if you will grow for 24 hours.”

Las Cruces Utilities Water Quality Laboratory Manager Luis Guerra shines a UV light to differentiate a control sample of E. coli from other containers containing clean water or bacteria. The lab made its grand opening on Aug. 2, 2019.
Credit Michael Hernandez

If the sample stays clear, Guerra said that means no growth has formed and the water is safe to drink. But if it turns yellow, there’s bacteria. To detect E. Coli specifically, technicians use a UV light. Guerra shined the wand on two control samples containing bacteria.

“And then we'll compare it to the other growth of bad bacteria. Total coliform here and E. coli. The way we can tell the difference between total coliform and E. coli is E. coli fluoresces," Guerra said. "This test is done. If we were to see any bad results in our system itself, we’d be required within 24 hours to notify the system and then let the public know that, you know, something’s wrong. But the City always has no news to tell, so no news is always good news for you guys."

While drinking water must be completely potable before it enters the water supply, Guerra said wastewater can contain some microorganisms as long as they stay within certain levels.

According to City data, the Jacob A. Hands Wastewater Treatment Facility treats an estimated 3.3 billion gallons of sewage per year. After processing and disinfecting the waste, the City discharges the effluent into the Rio Grande.

But before that happens, it must pass inspections by Senior Lab Technician Yadira Rena. She said making sure wastewater is properly treated before it enters the river is vital for the health of the environment.

“Our expectations is that when it's going out of the plant, anything that is discharged into the river because this is where our wastewater will go, we're making sure that it's not going to hurt any fishes or any other living organisms that are in the water," Rena said.

For example, Rena also tests wastewater for E. coli. She filled a sample cup with test powder before giving it a good shake. Rena said working in quality control can be challenging because of the level of focus required.

“It's very important that when we're running the analysis that we're paying attention. Working in a lab is very detail-oriented. So, we need to pay attention to every small detail. We need to know numbers, how those numbers come in on a daily basis," Rena said. "For example, they expect numbers to be in a certain range. We need to notice 'Hey, when that number's not in a certain range, something's going on here.' They need to be notified."

Rena carefully poured the test sample into a plastic tray, which gets sealed for incubation. A UV light test on an actual wastewater sample showed four tray cells testing positive for E. coli. She compareed that number against a table of range limits.

“And we have a reporting number of 4.1. Now for this plant at the Jacob Hands Wastewater Treatment facility, the exceeding limit would be 410. So, to have a 4.1 is awesome," Rena said.

In addition to having technicians like Rena on tap, Guerra said Doña Ana Community College students help the lab as interns as part of the school’s Water Technology program. Guerra said those who work at the facility take a personal interest in the water they test.

“They have a strong drive and love for the environment. Not only being homegrown here we're working, you know, as a job in trying to keep the environment safe but we actually have families in here. So, the job that we are doing here is not only professionally satisfying but actually it protects our families ourselves and the community themselves. So, what we do here is very important, you know, in all aspects," Guerra said.

Because everyone can drink to clean water.