Chlorine discharge kills fish in Las Vegas Wash

Wednesday, Dec. 31, 1997 | 11:12 a.m.

The Nevada Division of Environmental Protection is investigating a recent breakdown at the Las Vegas wastewater treatment plant that released enough chlorine to kill fish in the Las Vegas Wash, a state environmental official said Tuesday.

The NDEP is expected to issue a violation notice over the incident to the city wastewater treatment plant next week, said Allen Biaggi, the agency's deputy administrator in Carson City.

About 4:30 a.m. on Dec. 15 plant workers noticed that a sensor used to control chlorine entering the wastewater stream had shut down.

This allowed too much chlorine, used to disinfect and treat the sewage, to enter the Las Vegas Wash, Biaggi said. Roughly 50 carp and up to 24 catfish died from toxic exposure to chlorine, Biaggi said.

"They caught it right away," he said of plant workers on duty at the time of the chlorine release.

It took three hours for the crew to correct the machinery to stop pumping chlorinated water into the wash.

An NDEP inspector along with city crews remained at the site during the breakdown, Biaggi said. The city's wastewater plant can treat up to 66 million gallons a day of sewage before sending it to the Las Vegas Wash.

The wash is located about six miles upstream from Southern Nevada's drinking water intake pipeline. Once the effluent has been exposed to chlorine, the disinfectant is removed to prevent events such as the fish kill, Biaggi said.

After the state issues a violation notice, investigators will examine why the plant broke down in greater detail, Biaggi said.

Then the state will issue any penalties or corrective actions deemed necessary.

"At the minimum, we will issue a notice of alleged violation," he said.

A pump leading to a chlorine sensor apparently broke down, allowing chlorinated water to run into the wash, according to Debbie Hauth, spokeswoman for the city Public Works Department.

In addition to notifying the state, the city also called Clark County, Henderson and the National Park Service, Hauth said, alerting them to possible larger amounts of chlorine than normal arriving downstream.

However, the chlorine did not escape the wash in a concentration great enough to harm other living things, Biaggi said.

The city, like the two other wastewater treatment plants in Clark County and Henderson, operates under a discharge permit issued by the state.

By law, a discharger must take "all reasonable steps to minimize damage from a problem that upsets water quality."