Concerns rise over severe flooding risk Snowpacks, spring rains key factors

With snow still coming down by the foot seemingly every week, it may not feel like spring is around the corner.

But the combination of large snowbanks and warmer temperatures – whenever they finally arrive for good – has heightened concerns about severe spring flooding throughout Maine.

On Thursday, more than 20 field researchers, emergency management officials and dam experts will gather in Augusta to discuss the potential for flooding as one of the snowiest winters in recent history melts away.

“The flood potential is going to be higher because of the snowpack,” said Greg Stewart, data section chief for the U.S. Geological Survey office in Augusta.

Many areas of Maine are already well on their way to getting into the record books for total snowfall this winter. Bangor was just an inch or two shy as of Wednesday evening of breaking into that city’s top 10 snowiest winters, according to figures provided by the National Weather Service.

Caribou, meanwhile, already has recorded more than 160 inches, which is enough to rank the 2007-08 season No. 2 since record-keeping began in 1939, the NWS said.

Snowpack figures are only one of many factors that members of Maine’s River Flow Advisory Commission will be examining Thursday, however. The biggest factor – namely, how Mother Nature behaves in the coming six to eight weeks – is the one that’s impossible to predict.

“I’ve seen huge snowpacks just evaporate,” said Dana Murch, who oversees dams and hydropower facilities for the Maine Department of Environmental Protection. “On the other hand, if we get two inches of rain and really warm weather,” the likelihood of a flood rises considerably.

Scientists attempt to determine the flooding potential by measuring not only the size of the snowpack but also its density and water-holding capacity. Right now, most snowpacks have the capacity to absorb some rain like a sponge. But as the snowpack becomes more dense, rain will roll off and swell rivers and streams.

If Wednesday was any indication, some areas of Maine could be in for a soggy start of spring.

The National Weather Service issued a flood advisory for areas of central Maine on Wednesday afternoon as the early-morning snow and freezing rain changed to plain old rain. Localized flooding was reported in several areas.

At least one flooding factor is low this year, however.

“You can never be sure with predictions, but the ice jam potential is going to be considerably lower this year,” Stewart said.

Maine’s hydropower facility owners along the state’s major rivers – especially the Penobscot, Kennebec and Androscoggin – also play a key role in flood mitigation.

State officials work with the owners of the dozen or so major impoundments around Maine to decide how much to draw down the water levels in these storage lakes before the big spring melt. By releasing water well in advance, they can then use Moosehead, Chesuncook and other impoundments to absorb much of the spring melt.

“They are really looking at historic records and current conditions and deciding whether they should make a bigger hole in their lake,” Murch said.

Lynette Miller, director of special projects for the Maine Emergency Management Agency, said 1987 has become the benchmark year for spring flooding. An April Fool’s Day storm that year dumped up to 8 inches of rain in the mountains, which combined with the saturated snowpack to cause millions of dollars of damage.

The state has been relatively fortunate in recent years and escaped major flooding, at least among the large rivers, Miller said. She hopes this season’s heavy snows will at least help raise awareness about the potential for floods.

“If it gets people thinking about it, … then that’s the positive part of having a lot of snow,” Miller said.