Jonathan Thornton 720-450-7554 thorntonj@bouldercolorado.gov

If it becomes established, EWM grows quickly, forms thick mats and disrupts aquatic ecosystems. The invasive plant is not harmful to humans.

With this discovery, the city will work closely with Colorado Parks and Wildlife this fall to determine whether the plant has been established in the Reservoir.

The city has watercraft inspection and aquatic nuisance species (ANS) programs in place at the Reservoir to protect water quality and recreation. Despite these robust efforts, EWM may have arrived at the Reservoir via wind, fishing, animals, humans or watercraft. This plant can easily be transmitted without the carrier’s knowledge.

“The extent and location of EWM in the Reservoir is not yet known as just a fragment was discovered,” said Parks and Recreation Director Ali Rhodes. “We’ll work with Colorado Parks and Wildlife, who will conduct a more comprehensive aquatic plant survey this fall to determine the extent of the invasive plant’s growth at the Reservoir.”

If EWM establishes and spreads at the Reservoir, the following services could be impacted:

At this time, the city and Northern Water are not planning to make any changes to water supply operations or recreation activities at the Reservoir. The city will continue to run its existing watercraft inspection and decontamination program and implement the following additional precautionary measures to minimize EWM’s spread and educate Reservoir visitors:

The city encourages all visitors who enjoy the water to follow a “Clean, Drain, and Dry” practice to confirm that they are not transporting any ANS, such as EWM, to or from the Reservoir.

With more information from Colorado Parks and Wildlife’s follow-up survey, the city will evaluate EWM mitigation strategies or future adjustments to recreation and water utilities operations.

“Although this invasive plant doesn’t affect public health, because it could impact water quality and recreation activities in the future, we will work closely with Colorado Parks and Wildlife to get more information and keep the community informed about any impacts and changes at the Reservoir,” said Rhodes.

More information will be posted at boulderparks-rec.org and bouldercolorado.gov/locations/boulder-reservoir.

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