The City of Ketchikan is seen from the water on a cloudy day.

The City of Ketchikan is seen from the water on a cloudy day.

The Ketchikan City Council meets Thursday, and an issue related to the city’s source of water will be up for discussion and consideration.

Here’s the good news: Ketchikan’s new chloramine water disinfection system so far has brought down the levels of regulated byproducts. They tested under the limits set by federal regulators, and city officials hope that trend will hold through the warmer months, so the city can continue to avoid building a filtration plant.

Here’s the bad news: The city’s raw water supply – the source prior to treatment – has its own set of problems. And that could prompt the federal government to require an expensive filtration plant, after all.

Environmental Protection Agency requirements for unfiltered surface-water systems are strict. In addition to regulations for the treated water that comes into people’s homes, the EPA has requirements for the source water, before it’s treated.

Ketchikan Lakes is the city’s source, and before 2011 it always tested OK. Since then, though, it has exceeded allowed levels of coliform.

Coliform can come from fecal matter deposited by animals living in the watershed, but it also is formed by the natural decay of wood and other organic material. The city stresses that coliform is destroyed through its water treatment system.

The concern is what could happen if that treatment system fails.

Last year, the city hired consulting firm CH2MHill to study the source water at Ketchikan Lakes. In a recent report, the consultants say that weather pattern changes could be the reason for the increased levels.

According to the report, spikes in coliform levels have been associated with periods of warm, dry weather followed by heavy rains.

Possible ways to fix the problem without resorting to filtration include changing the location of intake pipes to deeper in the water; and controlling the flow of runoff from one area that could be the source of contamination.

CH2MHill recommends continuing the study for another year, and state Department of Environmental Conservation officials have agreed that would be the reasonable next step.

The Ketchikan City Council will consider authorizing a $31,000 contract with CH2MHill to continue the work.

The Council meeting starts at 7 p.m. Thursday in City Council chambers. Public comment will be heard at the start of the meeting.