A jammed gate in Ottawa's sewer system has led to another raw sewage spill in the Ottawa River and a precautionary no-swim advisory for the Petrie Island beach downstream.

Dave McCartney, manager of wastewater and drainage services for the City of Ottawa, said the incident occurred early Saturday morning when a regulator on Booth Street was jammed open with sand and debris following Friday's heavy rainfall.

The gate was fixed within two hours, and both public health and Ontario's Ministry of the Environment were immediately notified, McCartney said

A similar incident occurred in 2006 — when the same type of gate remained stuck for 15 days, sending an estimated 1.2 billion litres of raw sewage into the river — and was blamed for high bacterial counts and 45 "no swimming" advisories at Petrie Island beach that year.

McCartney said the city is in the process of trying to estimate the volume of toilet, sink, laundry and storm sewer waste that spilled into the Ottawa River on Saturday .

The city's public health department issued a no-swim advisory for Petrie Island beach in the city's west end as a precaution.

Gates are 50 years old

Five 50-year-old regulator gates, including the one that jammed on the weekend, are integral parts of the city's combined sanitary and storm sewage system, and they are routinely inspected after heavy rainfalls.

McCartney warned that more spills are likely to happen as the city's infrastructure ages.

The city is planning to upgrade the regulators and put in a system that uses computers and automated gates to minimize sewage spills, he said, but it would be too expensive to do all that at once.

Eliminating spills altogether would require building a sewage storage facility or expanding the sewage treatment plants and building more pipes. That could cost $300 million, he added.

Coun. Bob Monette, who represents the ward containing Petrie Island beach, said in this case, city staff followed proper protocol.

However, given that it is the second such spill in two years, he wonders whether something might be done to prevent the spills.

He also warned the public to be careful about visiting beaches before noon, as bacterial counts are done at 11 each morning.