State environmental regulators are overseeing upgrades to a Denton city wastewater system near Lewisville Lake after rains on May 2 caused it to overflow twice, spilling 2,500 gallons of sewage onto nearby properties and into a private pond.

Local and state officials say the spills — the 10th and 11th at the Grissom lift station in far east Denton since 2002 — weren’t big enough to pose a danger, and the city won’t face a fine.

Still, some area residents are outraged, saying spills from the outdated lift station are ruining their land and endangering pets and livestock that drink from the pond.

“They have just flat taken our property — they’ve taken the value,” said Ginger McCormack, who lives across the street from the lift station on South Trinity Road, which straddles the city limits line. “I have no clue what it’s going to take to clean it up.”

The city is spending some $400,000 on sewer system upgrades to prevent future spills at the lift station, according to records filed with the Texas Commission on Environmental Quality.

But officials say no cleanup is needed at the pond, which borders several private properties.

Neighbors “shouldn’t necessarily be concerned about the water in that pond,” said Vanetta Webb, a city consultant on water issues, acknowledging that samples taken after the May 2 spills showed minor traces of fecal matter. “If I don’t see any dead fish, then chances are it’s as safe as it’s going to be.”

State environmental officials say the city is handling the problem appropriately.

“The city is taking reasonable steps to respond and to come up with some long-term solutions to the situation,” said Sid Slocum, TCEQ water safety manager for the Dallas-Fort Worth region. “They had a discharge, but they did not report what we would call a documented environmental impact, such as a fish kill.”

To residents like McCormack and neighbor Pat Blankenship, those explanations aren’t reassuring. They’re fed up with sewage problems, they say, including the failure May 29 of a private sewer system for a mobile home park that spilled an estimated 1,200 to 2,000 gallons into the pond, according to records.

Nancy Rose, the manager of the Denton Falls mobile home park, described the May 29 spill as small and said it was quickly cleaned up.

The neighbors say the issue affects more than just them, noting that excess water from the pond flows into nearby Lewisville Lake, a regional source of drinking water.

“Is our pond safe? I ask the same question [repeatedly],” McCormack said. “The only response I get is that there was no fish kill. What does that have to do with anything?”

Lift stations are used to pump sewage through pipes from lower to higher elevations, and heavy rains or equipment failures can cause them to overflow.

City officials blame the May 2 spills on pump failure during a storm that dropped 5 inches of rain. They reported the spills to TCEQ within 24 hours, as required by law, according to state records.

City records show nine other reported spills at the lift station since 2002, the earliest year for which records were available. The lift station is believed to be about 40 years old, said Webb, the city consultant.

The spills include two 49,500-gallon overflows during a 10-inch rainfall April 24, 2007 — part of a storm that flooded much of the city. Webb blamed most of the spills on heavy rains and said only a couple involved equipment failures.

Still, city officials knew that overflows from the Grissom lift station had been “an issue for some time now” because it lacks the capacity to handle flow from an upstream lift station, according to the TCEQ investigator’s report.

For years, city officials planned to upgrade the area sewer system in partnership with a private developer, Canyon Energy Partners Ltd., according to records filed with the state. The developer bought more than 400 acres and planned to build roughly 1,300 homes but repeatedly postponed construction, eventually causing the Planning and Zoning Commission to deny an extension of the plat, records show.

Now, the city is working independently to improve the system, including adding wider pipes and larger pumps, according to plans filed with TCEQ.

State officials required the city to submit a plan to fix the problems, along with quarterly progress reports. City officials expect the work to be done within six months.

McCormack said the state investigation failed to take a comprehensive look at the problem, including the May 29 mobile home park spill. She said she’s notified several elected officials, including Mayor Mark Burroughs, and is considering legal action against the city for property damage.

Burroughs said he asked city staff members for a full report on McCormack’s concerns.

“I understand the problems out there have been there for at least some length of time and I acknowledge that something’s got to get done,” he said. “What that actually means, I’m awaiting the report to help elucidate that for me.”

LOWELL BROWN can be reached at 940-566-6882. His e-mail address is lmbrown@dentonrc.com.