For the second year in a row emergency officials have opened two diversion ditches near Mayo to alleviate winter flooding of the Mayo River.

Just before Christmas last year, rising river waters infiltrated dikes and flooded parts of the yard where Yukon Energy has its diesel generation plant, about 300 metres from the river.

Officials say they were forced to act again two weeks ago after flooding in a new spot, in the McIntyre Park area, was cutting off access to the emergency diversion ditches themselves.

"If we hadn't taken action, we faced the possibility that we'd lose the solution from last year's issues to keep the village safe for this winter,” Chris MacPherson, an emergency measures planner, told a news conference Tuesday afternoon in Whitehorse.

The two channels, located about a kilometre north of the village, had been sealed off following last year's flooding to protect the environment in the area.

"Whenever we are doing these works, we do them under emergency authorization from a number of different acts,” MacPherson said.

"While that allows us to go around existing permitting processes, when we're finished, we need to observe responsibilities, to clean it up and make sure we haven't left any lasting damage.”

MacPherson said leaving the channels open over the warmer months could have affected salmon breeding in the river.

Since the channels were completely reopened as of last Saturday, the flooding appears to be under control, he said. However, officials are currently looking for expert help to prevent future problems.

"Last year's flooding was in a much more localized area; this year, we're seeing it in areas that we didn't see last year,” MacPherson said.

"It really indicates to us that there's a number of factors at play here and we're trying to gain a further understanding of what those factors are.”

Finding that help may prove a challenge.

"One of the immediate things that comes up is that there's very little in the scientific literature talking about small stream flows such as the one we're dealing with,” MacPherson said.

"So in many ways, we're being told that there's new ground being covered here, so a lot of the work has to start from scratch.”

Last year, some expressed concern that work on new hydro generation facilities may be causing the flooding, but Yukon Energy says there is no extra water going into the river.

"Last year, we did not change anything; we ran the existing Mayo facility as we always would run it,” said Lawrence Joudry, director of engineering services for Yukon Energy.

"This year, we're just finishing the commission of the Mayo B unit (see separate story, p. 7), so there is no additional water being put down the Mayo River.”

"Last year, there was a lot of focus around the berm dike structure; however, since we've seen a different presentation, we really need to go back and look at what those solutions might be,” MacPherson said.

"Given the pattern of flooding, it's obvious that the dike alone is not the one and only solution.”

So far this year, about $200,000 has been spent dealing with the flooding.

Last year's effort cost about $360,000 plus restorative work through the summer and fall.

The flooding has not damaged any homes nor affected the village's water supply.