MISSOULA — The City of Missoula has partnered with the University of Montana’s pesticide monitoring program to study which contaminants are emerging in local watersheds.
Pesticides were found in Pattee Creek, however, while the City says levels are currently low, they’re looking into how this impacts the environment and how to better water quality.
“We have six sites across the city, including one that's actually upstream of the city. So we can kind of see what kind of water quality is coming into the city and what is leaving," City Stormwater Superintendent Tracy Campbell told MTN.
The City of Missoula is required by the Environmental Protection Agency (EPA) to monitor where runoff meets the rivers.
That’s why they teamed up with the University of Montana’s (UM) Pesticide Stewardship Partnership Program, which samples 12 western Montana counties for contaminants.
"Really want to have our runoff from our subdivisions, roads, to not be negatively impacting water quality," Campbell said.
Through a multi-million dollar EPA Upper Columbia River Basin Toxic Reductions grant, UM’s program has been helping the city by collecting data on emerging contaminants.
"We have 102 different pesticides, which is really a drop in the bucket of how many pesticides are out there. But, that's the number that the lab can analyze," Flathead Lake Biological Station Assistant Research Professor Rachel Malison explained.
At Pattee Creek, two sites were sampled in 2025. One was sampled once and the other twice.
"Think of the data that we collected as more of a snapshot. This is not a Pattee Creek is contaminated everywhere or we know about how it is in time or anything, but just an indicator that we are finding some things there," Malison stated.
Pesticides like Carbaryl, 2,4-D, and others were found.
“Tebuthiuron, diurin, prometon, some other pesticides too," Malison added.
The City attributes these chemicals to lawn and landscape spraying. Yet, remnants are lingering for months in the water, long after a spring or summer spray.
"Most of our sites, the levels are pretty low, so it's not a human health risk, but the fact that we're finding them in the water as an ecologist makes me concerned and we don't know exactly what they do to all of our aquatic insects. Especially in combination with other things and if they're present in the water for a long time period," Malison detailed.
When a contaminant is detected, opens opportunities for further funding to address it.
"They do stick around. Even if they break down, they can break down into another kind of pesticide that can take a really long time. So, a lot of our efforts are focusing on what can we do, how do we help people understand what other options there might be, and then if pesticides are the tool to be used, what are the right things to do? Like the right kind of pesticide, the right time to use it, the right amount, all of those things," Malison said.
One of City Stormwater's goals is to institute more environmentally friendly practices. One can be seen at Takima Park off of Pattee Canyon Drive.
"Things like constructed wetlands, bio-retention basins, things that can help to use nature to mitigate for pollutants and trap them," Campbell explained.
For further information and ways to volunteer with the monitoring program, click here.
