Water and Sewer holding ponds being tested for leaks

Lab to dye ponds as part of yearlong lawsuit

By Bella Butler EBS STAFF

Editor’s Note: This story was updated on July 14 following the dyeing of the wastewater holding ponds.

BIG SKY – Last year, a lawsuit was filed against the Big Sky County Water and Sewer District alleging the wastewater holding ponds were leaking and effluent was finding its way into the Gallatin River. Within a month, it could be clear whether or not the pond liners are leaking.

On July 14, a hydrologist from a Missouri-based lab colored the district’s holding ponds with a bright green tracer dye to perform tests related to a lawsuit between the district and plaintiffs Cottonwood Environmental Law Center, Montana Rivers and Gallatin Wildlife Association. 

The lawsuit, filed July 10, 2020, alleges that the district is violating the federal Clean Water Act by discharging polluted water leaking from the holding ponds into the West Fork of the Gallatin River without a National Pollutant Discharge Elimination System permit. The district countered during an interview with EBS on July 9, stating that it discharges water from an under-drain system that collects groundwater and transfers it back into the river through pipes that run beneath the holding pond liners. 

In order to find out if the holding pond liners have tears and are leaking, allowing wastewater to be discharged into the West Fork, the plaintiffs hired Missouri-based Ozark Underground Laboratory to dye the holding ponds with fluoresceine, a fluorescent tracer dye, that the lab can then track.

“We’re just doing the test and answering the question: does it leak and can we detect it?,” Tom Aley, the hydrologist with Ozark Underground, told EBS on July 13.

In addition, several samplers have been placed in the Westfork that will detect whether the fluoresceine-dyed wastewater makes it into the Gallatin River tributary, according to John Meyer, executive director of Cottonwood and the attorney representing the plaintiffs in the suit.

Meyer said in a July 8 interview with EBS that the plaintiffs had samples collected and tested of the water being discharged into the West Fork prior to filing the lawsuit and found “high levels of nitrogen.” This led the plaintiffs to believe that the water being discharged is wastewater, which requires a permit to be discharged. 

“[The district] created a tributary of what they call groundwater and we think it’s just wastewater,” Meyer said. “We have reason to believe the liners are ripped and … they’ve created a tributary to the West Fork that’s probably just pollution.”

Ron Edwards, executive director of the water and sewer district, is named as a defendant alongside the district. “We don’t think that [the ponds are] leaking,” Edwards said during a July 9 interview with EBS. 

Whereas the plaintiffs’ tests that yielded high levels of nitrogen were conducted in-stream, the district pulls water samples directly from the under-drain groundwater and has not found high levels of nitrogen, according to Edwards. 

“I don’t have any presumption of what they’re going to find,” Edward said, later explaining that wind drift from the nearby golf course irrigation could affect the outcome. “Every night we’re irrigating and if [effluent used for irrigation] were to blow in stream it could show up as a positive in their samples,” he said.  

A series of samples will be collected over a period of 42 days and will be split between the district and the plaintiffs. The plaintiffs’ samples will be processed at Ozark and the district will send their samples to another lab to ensure accuracy. Results will be available after the last sample is collected 42 days after the ponds are dyed. 

The green dye is the same as what is used to turn the Chicago River green every St. Patrick’s Day, and Meyers, Aley and Edwards said the dye will not have significant environmental impacts. 

In a public notice, the water and sewer district said the holding ponds, which are visible from many areas around Big Sky including from Highway 64, are expected to be bright green for two to three days, though the dye is not expected to impact water in Big Sky homes. 

The district added that landscaping and golf courses irrigated with the treated wastewater should not be impacted other than potentially visible traces of bright green that should not be of concern.