Local communities prepared for the expected arrival of Hurricane Irene late today by urging residents of vulnerable neighborhoods to evacuate, activating disaster plans, preparing to open emergency shelters and checking storm drains and other infrastructure.

One major concern, in addition to the wind damage expected from the hurricane, is possible flooding from the 5 to 10 inches of rainfall and storm surge during high tide at about 9 tonight.

"The ground's already saturated," noted Joseph Sastre, Groton's emergency management director. "Is it possible the same neighborhoods that were flooded a year ago will get flooded again? Absolutely."

While the March 2010 flooding was mainly inland and caused by heavy rainfall and overflowing rivers and streams, the flooding Hurricane Irene is threatening to bring could affect both coastal and inland areas with both sea water and fresh water.

The Northeast River Forecast Center has identified the western two-thirds of Connecticut and a band to the north through Massachusetts and Vermont, New Hampshire and Maine as an area where "significant river flooding is likely" through Tuesday.

The remainder of eastern Connecticut and New England is identified as an area where "significant river flooding is possible" through Tuesday. The forecast center is part of the National Weather Service.

High groundwater levels

Virginia de Lima, director of the U.S. Geological Survey's Water Science Center in East Hartford, said Friday that stream gauge and groundwater data indicates that rivers and streams could reach flood stage relatively quickly with the heavy rains predicted. Already this month, the New London County area has had about five inches of rain, about two inches above normal. Rainfall totals for the year thus far are also above normal.

"The streamflows are up, and the groundwater levels are relatively high, so there's not a lot of storage capacity left in the hydrological system," de Lima said.

On Friday and today, USGS teams from her office were placing 30 storm surge monitors at locations along the Connecticut coast and the state's major rivers. The monitors will document the height of the surge and how far inland it travels, she said, as well as the data used to refine the U.S. Army Corps of Engineers flood maps.

Sastre, the Groton emergency management director, said areas of town he's concerned about include Groton Long Point, Mumford Cove and River Road in Mystic, which was flooded in March 2010. River Road, he noted, is vulnerable both from tidal waters surging upriver and rainfall draining from the north.

"We prefer people to get out before the storm," he said.

Making a call

on ordering evacuations

Town officials in Groton and several other communities planned to meet today after consulting the latest storm forecasts to determine whether to order evacuations. Several towns, including East Lyme, Old Saybrook, Waterford and Stonington, on Friday asked residents of vulnerable neighborhoods to voluntarily evacuate and announced the opening of shelters. Several towns also declared states of emergency.

Westerly issued a mandatory evacuation order for Shelter Harbor and all residents and businesses in the Weekapaug, Misquamicut and Watch Hill areas. Residents are to leave by 6 p.m. today.

In Old Saybrook, Emergency Management Director and Police Chief Michael Spera and First Selectman Michael Pace met Friday afternoon with the heads off eight beach neighborhoods. Spera announced that town emergency crews would go door-to-door starting at 8:30 this morning to urge residents of those neighborhoods to leave well before the storm begins.

Flooding of roads could isolate some neighborhoods, he warned, making it impossible for people to leave if they wait too long. All the areas south of Route 1 are considered vulnerable, Spera said. The causeway to Saybrook Point on Route 154 will be closed at the beginning of the storm.

Paula Satmary, president of the Cornfield Point Beach Association, said many of the homes in her neighborhood are on high ground out of the flood zones, but a few are in low-lying areas. Most of those on high ground plan to stay, she said.

Another beach association president, who asked not to be named, said residents of lower areas in her neighborhood are relocating to neighbors' homes in safer areas.

"The people next to the water will move to higher ground," she said. "I don't think there'll be any resistance."

One beach association president said some residents might be reluctant to leave for fear of looting. Spera assured him that there will be police stationed in all beach neighborhoods.

'If it's flooded before,

this time it will be worse'

In Stonington, First Selectman Ed Haberek said some of the areas most vulnerable to flooding from Hurricane Irene are Mason's Island, Stonington Borough and parts of Pawcatuck, which endured heavy flooding in March 2010.

Friday evening, the town sent a message to residents of low-lying and flood zone areas that they are in a "likely mandatory evacuation zone" and strongly urged them to evacuate.

"We also advised them that we cannot guarantee that emergency services will be able to respond to them in the hurricane," Haberek said in an email message.

Waterford First Selectman Daniel Stewart urged residents in the Millstone, Mago Point, Pleasure Beach, Ridgewood and The Avenues neighborhoods to be particularly aware of their vulnerability to flooding.

Keith Chapman, interim public works director for New London, said residents should be prepared for overflowing storm drains and road flooding. Some of the area along Pequot Avenue are the most flood-prone.

"Our stormwater system will not be able to handle" all the rain that's expected, he said. Chapman urged people to stay away from any downed utility lines and to have patience as city crews work to clear any downed trees and reopen blocked roadways.

Chapman reminded drivers not to drive through any water deeper than 4 inches and asked that people not drive their vehicles during or immediately after the storm.

East Lyme First Selectman Paul Formica warned residents that "a good rule of thumb is that if it's flooded before, this time it will be worse."

He said town engineers would lower water levels at Powers Lake, Pattagansett Lake and Gorton Pond to create extra storage capacity for rainwater and minimize flooding. Residents along Pine Grove Road will have access to Camp Niantic to reach their houses if floodwaters make that road impassable.

Waterford and East Lyme will join with Lyme and Old Lyme in operating a shelter at East Lyme Middle School that will be able to house up to 500 people. Old Lyme First Selectman Timothy Griswold said many of the beach neighborhoods south of Route 156 are vulnerable.

j.benson@theday.com

Day staff writer Stephen Chupaska contributed to this report.