The sewage coming down the Cannon River has dissipated to the point people may again swim in Lake Byllesby.

Goodhue County temporarily closed the beach Tuesday, July 3, following the discharge of up to 1 million gallons of sewage that day from the Northfield wastewater treatment facility. The ban was lifted at noon on Friday, July 6.

The closure was systematic from the moment Northfield alerted authorities downstream that day and involved Goodhue County Sheriff's Office, Public Works and Land-use Management as well as Dakota County officials.

"When the Sheriff's Office was contacted reference the spill, we did send deputies over to Byllesby to alert the people that were using the lake and beach area. The Sheriff's Office also made contact with rental agencies along the Cannon River to alert them - Cannon Canoe Rental and Welch Mill Canoe and Tubing," Sgt. Scott Powers said Friday.

Goodhue County Public Works barricaded the beach off. Both agencies then posted warning/advisory signs along the beach and at boat access areas on Byllesby.

The Goodhue County Lake Byllesby Park amenities remained open, but the public was advised not to have direct contact with the water. Risky activities included swimming, tubing, water-skiing, paddle-boarding or other recreational activities. Boating and fishing were permitted, but anyone who has contact with water while launching boats or fishing should wash with soap and clean water. Those warnings apparently were enough to deter anyone from using the park.

"Our Water Patrol checked the lake on the Fourth and there was no boat traffic on the lake and Byllesby park was empty. For the most part, people did heed the warnings and stayed out of the water on Lake Byllesby," Powers said.

The Cannon River flows into Byllesby Reservoir, which widens into a "lake" because of the Byllesby hydro-electric dam. Dakota and Goodhue counties have parks along the reservoir.

Dakota County Parks started sampling water at Lake Byllesby that afternoon and followed state health recommendations on testing, Goodhue County officials said. When results from at least two consecutive days of sampling indicated the water had returned to safe levels for contact, Dakota County will reopen Lake Byllesby beach and Goodhue County Lake Byllesby beach will follow.

In its advisory to local authorities, Northfield reported that at 8 p.m. Monday, July 2, staff at the wastewater facility responded to an alarm. They determined a PVC pipe had broken. The facility then operated under "critical to stable condition," according to Northfield Public Works Director David Bennett.

The discharge occurred between 1-4 a.m. July 3, and the Minnesota Pollution Control Agency was alerted.

Bennett said the approximately 1 million gallons of treated and untreated wastewater that entered the Cannon is less than 1 percent of the river's total flow during the three-hour time frame.

Northfield officials initially advised no contact with water downstream of the city through 6 a.m. Friday, July 6. That was extended to 2 p.m. due to test results.