Complaints about increased mosquito activity near Ridgway State Park have prompted officials to ask what happened with preventative treatments, which usually happen in the spring and curb the population of nuisance pests.
It seems a disagreement over how leftover larvicide was stored led to the state park not receiving treatment earlier this spring, when the application is most effective.
The majority of the complaints appear to be from residents in Dallas Meadows — the subdivision nearest to the southern boundary of the state park — and visitors to the state park and surrounding areas. Several Dallas Meadows residents showed up to voice concerns during the Ouray County commissioners’ meeting Tuesday morning.
“This is a health issue. This is a quality of life issue,” said Dallas Meadows resident Holly Bennett, who told commissioners she can’t leave her house without being surrounded by a cloud of insects.
She said she hasn’t noticed such a big problem since 2014, when the town of Ridgway created a mosquito control map and hired its current employee to perform mitigation to control the population, including at Ridgway State Park through an informal agreement with Colorado Parks and Wildlife.
Most years, the town performs treatment with fresh larvicide purchased by the park. But that handshake agreement fell apart this year when the park didn’t respond to the town’s request for fresh larvicide or inquiries about performing treatment, according to a town employee. According to information provided to the county health department by the park, CPW used larvicide it had on hand just last week — months after Ridgway Reservoir filled high enough to create breeding ground for mosquitoes and beyond the window of time considered effective for application in the mosquito season.
Mosquito treatment history
Ouray County and its municipalities don’t have a formal mosquito control district, which is used in some other places to keep tabs on and treat mosquito populations.
One Dallas Meadows resident raised the possibility of creating such a district to control the pests here during Tuesday’s commissioners’ meeting.
But historically, the town of Ridgway has taken on the task and charged other local government entities for the treatments.
According to Plaindealer archives, Ridgway began mosquito control in 1965, spraying chemical treatments by plane. The program had intermittent pauses and varying methods of control. In 1980, the town switched its mosquito control method from “broadcast spraying” to using larvicide. The town currently uses a granular larvicide called VectoBac G to kill mosquito larvae before they mature into adult insects, according to the town’s employee who applies the larvicide.
In 2014, the town hired Rodney Paulson to perform the town’s annual treatment, which usually begins in late spring. It depends on when snowmelt begins filling the reservoir, creating mosquito breeding grounds. Mosquito eggs laid in stagnant water begin hatching into larvae within 48 hours after being submerged. Female mosquitoes can live up to six months, with an average lifespan of six to eight weeks, and the insects are much harder to control once they reach adulthood.
When Paulson started, the town created a map informing where and when he applies treatments on a weekly schedule. The majority of those locations are outside of town limits. The 2014 map designates high-problem areas for early treatment, including Ridgway State Park. Paulson said he monitors reservoir levels using U.S. Geological Survey records.
“I kind of need to be down there the minute that water starts hitting the terrain where the eggs are laying,” he said.
The funds for treatment come from the town and county. Since at least 2019, Ouray County began contributing $8,000 to the town’s mosquito control efforts, which vary in cost year to year, according to Ridgway Town Manager Preston Neill.
In 2024, the town reported spending $13,200 on larvicide, around $1,000 in gas money and 660 hours of staff time on treatment.
According to Paulson, the town’s agreement with Ridgway State Park for mosquito control on the property is a handshake agreement, rather than in writing. The town performs treatment if the park purchases its own larvicide, which usually costs between $4,000 and $5,000, he said.
The disagreement
Paulson said he didn’t treat the areas of Ridgway State Park this spring because of a disagreement over how the state park stored leftover bags of larvicide granules.
He told the Plaindealer he was concerned about the efficacy of 10 bags of leftover larvicide the park left outside in the snow and sun. He said he asked a state park employee to purchase new larvicide, since the leftover bags were stored improperly. He said he learned the park wouldn’t purchase new larvicide for the town this year until the old larvicide was used.
The park employee didn’t return multiple requests for comment from the Plaindealer. The Plaindealer also attempted to contact Ridgway State Park interim manager Jed Potter for comment but didn’t receive a response.
Paulson said when he asked about beginning treatment and the park purchasing fresh larvicide this spring, he never heard back. He figured it wasn’t worth the effort to apply larvicide he wasn’t sure was going to work.
“You’re in some of the nastiest, willowy terrain. I mean, you get lost in there. Sometimes you don’t even know which way is out,” Paulson said. “I’m thinking, if I’m going to go in there and basically sacrifice blood, sweat and tears, because I do usually, that I didn’t want to be using a product that might not be effective.”
Hearing nothing from the park, Paulson said he only performed treatment within town limits and on private property where he had approval to do so.
County Vegetation Manager Julie Kolb said she also has received several complaints about mosquitoes. She isn’t involved in mosquito control, but holds a pesticide applicator license and believes any larvicide left in an uncontrolled environment for more than a year is likely ineffective.
“I do support Rodney in that,” Kolb said. Colorado Parks and Wildlife spokesman John Livingston said park employees this year “decided to utilize a stockpile of granules that the park still had on hand at the park,” in comments he emailed to the Plaindealer.
According to Ouray County Public Health Director Kristin Kelley, who said she spoke with the park employee responsible for ordering larvicide, it was only applied last week, long after the breeding season began.
Kelley said the employee told her the larvicide was not expired. CPW refused to answer requests from the Plaindealer for more information, including how the larvicide was stored, whether it was expired or when the treatment was applied.
“If there is a need for additional mosquito control at the park this summer, the park will look into possibilities of ordering more product and distributing it as needed,” Livingston wrote in an email.
According to Paulson, the window of time where larvicide is effective has already passed, now that peak adult mosquito season has arrived.
“Once the mosquitoes are airborne, I can’t do anything about them anyways. I’ve never had the ability of killing adults,” Paulson said.
What now?
Officials will discuss possible solutions during a work session next week, including whether anything can be done to mitigate this crop of adult mosquitoes, using tools such as traps.
Kelley told commissioners she believes future treatment at the state park should be resolved through a formal agreement, rather than the current informal arrangement.
She’s also exploring options for testing the insects for mosquito-borne diseases such as West Nile Virus. The county doesn’t currently test its mosquitoes and would need to find funding for the program to begin testing.
According to Livingston’s emailed comments, “Ridgway State Park looks forward to continuing the previous partnership with the Town of Ridgway on mosquito control in future years and appreciates that relationship with the town.”
Lia Salvatierra is a journalist with Report for America, a service program that helps boost underserved areas with more reporting resources.
