Water contact advisory for John Martin Reservoir as Pueblo sewage spill moves downstream; arrival anticipated Monday

Sunset at John Martin Reservoir State Park, Aug 29. Park officials are in coordination with the Colorado Department of Public Health and Environment and the Colorado Parks and Wildlife water resources staff as 4.2-million gallons of untreated sewage makes its way down the Arkansas River from Pueblo. The sewage is expected to reach the reservoir on Monday. CPW Photo/Justine Butchart

Aug. 30, 2026

HASTY, Colo. – Colorado Parks and Wildlife advises visitors to John Martin Reservoir State Park to avoid contact with the Arkansas River and John Martin Reservoir beginning Monday, Aug. 31, as water affected by a 4.2-million-gallon untreated sewage spill in Pueblo moves downstream.

The sewage entered the Arkansas River in Pueblo Aug. 26-27 and is expected to reach the reservoir by Monday morning.

CPW is coordinating with the Colorado Department of Public Health and Environment and CPW’s Water Resources staff. That coordination has kept park staff informed as the spill moves downstream and allowed the park to prepare a monitoring plan. CDPHE will collect water-quality samples at the park.

“I’m grateful for the communication that has kept us up to speed from the onset,” said Dan Kirmer, JMRSP Manager. “While we cannot fix what is coming downstream, we have an opportunity to prepare and communicate with our visitors before it arrives.”

The park remains open and the advisory applies to activities involving direct contact with water in the Arkansas River and John Martin Reservoir.

Beginning Monday, visitors should avoid swimming, wading, tubing, paddleboarding, fishing and other activities involving direct water contact. Visitors should also keep pets away from affected water.

Warning signs will be posted at the park and around the reservoir to alert visitors to the contamination and water contact advisory.

The sewage spill comes as park staff are monitoring separate water-quality concerns involving cyanobacteria, commonly called blue-green algae. The reservoir was recently downgraded to a yellow caution level for possible algae-producing cyanobacteria and toxins, and regular testing continues.

Lake Hasty, a separate body of water at the park, remains under a red danger algae condition and closed to full-body water contact after its most recent test showed levels had increased again.

“Lake Hasty will not be impacted by the sewage spill, but its existing algae restrictions remain in place,” Kirmer said. “We will continue testing and communicating with our visitors as conditions change.”

CDPHE will collect water-quality samples at the park, and CPW will update the advisory as sampling results become available.

Visitors should follow posted signs and check the John Martin Reservoir State Park webpage for current park conditions and updates.

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