Even as they continue overseeing their towns' cleanup and recovery from Tropical Storm Irene, officials of lower Connecticut River communities still have to keep an eye on another possible threat.

The National Weather Service has issued a flood warning for the Connecticut River, from its northern reaches in New Hampshire and Vermont and as it flows south through Massachusetts and Connecticut. The main threats for flooding in Connecticut appear to be in Hartford and Middlesex counties, which could see "moderate flooding and possibly major flood levels on Wednesday," according to a weather service advisory Monday afternoon.

The river is still swelling with runoff from the heavy rains that came with the storm, which was downgraded from hurricane status as it reached Connecticut early Sunday.

The lower part of the river is not expected to crest until late Wednesday, the weather service said.

Old Saybrook First Selectman Michael Pace said Monday that he was hoping to meet with the chief elected officials of other lower river towns today to assess the situation and determine whether actions are needed to protect any areas.

At this point, the river flooding does not appear to be a major threat to riverfront neighborhoods in Old Saybrook, such as North Cove, unless the high river flows occur during or approaching high tide, he said.

There is extra capacity for floodwaters at the mouth of the river as it meets Long Island Sound, reducing the flood threat compared to towns to the north along narrower stretches of the river. There are also marshes along parts of the riverfront to absorb much of the floodwaters.

Pace said he witnessed the effectiveness of wetlands while touring his town after the storm and noting how marshes protected several beach neighborhoods.

"The tidal wetlands did their job," he said. "They accepted a phenomenal amount of water."

Tidal marshes also buffer much of the riverfront in Lyme and Old Lyme.

Old Lyme First Selectman Timothy Griswold said there are a few homes along the river that could see some flooding, but he doesn't expect extreme high water.

"It'll be like the spring high tides," he said.

j.benson@theday.com