ROCHESTER — The city called for a mandatory evacuation Monday morning of nearly 2,000 homes along Salmon Falls Road from the Spaulding Fiber Dam to the Maine border as rain continued to drown the region.

Authorities, using an automatic phone system, told residents to head to a shelter at Rochester Middle School and said the city planned to start a second shelter at Spaulding High School.

New Hampshire National Guard troops and emergency crews from New Hampshire and Maine toiled starting Sunday to secure the edges of Milton’s Three Ponds Dam with a slew of sandbags. The efforts allowed the dam to cope with five extra feet of water flowing into the Salmon Falls River, protecting communities downstream.

Milton Fire Chief Andy Lucier said Sunday night he was sure the dam would not lose structural integrity.

“The dams were never in jeopardy,” he said. “Our goal is to keep an even keel all the way down the river.”

The dam was opened briefly this morning to relieve some of the pressure.

The flooding concerns come after area firefighters a month ago were praying for rain to fall while they battled dry conditions. Now they hope for a reprieve from the rain after swollen lakes, rivers and runoff washed away roads, threatened dams and forced evacuations.

Lucier credited the untiring efforts of volunteers helping at the dam, which included firefighters and emergency personnel from Milton, West Ossipee, Rochester and Wakefield in New Hampshire and Lebanon and York County in Maine. Highway and road crews and prisoners from York, Strafford and Carroll counties also helped.

“Without these guys, we wouldn’t be here,” Lucier said Sunday evening.

While there were a few evacuations to the dam’s south, communities did not require more residents to leave their homes in low-lying areas along the waterway. Emergency crews watched the dam throughout Sunday night.

The battle to save homes, businesses and property throughout the area began on Saturday night as firefighters and road crews began coping with an increasing amount of water, which flooded basements, overflowed swamps and waterways and blocked culverts after heavy rains struck the region.

Their problems with roads, rivers and water mushroomed on Sunday morning. Town, city and state officials began shutting down numerous roads and highways after bridges were flooded and pavement buckled or collapsed when the underlying ground gave way because of the rains.

Wakefield firefighters and police at about 4:30 a.m. evacuated about 50 Union residents after the swollen waters of the Branch River washed over the Maple Street bridge, flooded a nearby business and began eroding the embankment about 10 feet away from a residence, according to Wakefield Police Chief Tim Merrill.

Merrill said police, firefighters and members of the Wakefield Public Works Department and New Hampshire Department of Transportation responded to assess and try to remedy the problems in Union.

Wakefield officials went door-to-door to alert residents and advise them to leave. Many were reluctant to leave, but agreed to the precaution.

“We live on Maple Street, and when we left, the water was already over the girders” of the bridge, said Seth Williams, 13, of Union.

Some sought shelter with other family members. About 20 residents stayed in the Public Safety Building for a few hours.

“I think we’d be high enough, but when they told us to get out — what do you do?” asked Adele Garvin, 60, who left with her 92-year-old father, Dell, and their three cats.

Police worked with local American Red Cross representatives to prepare in case more residents needed shelter.

“It’s all voluntary — you could go home if you want, but the problem’s not over,” said Wakefield Police Lt. Kenneth Fifield.

Merrill said it’s only a matter of time before water in the higher areas descend into the lakes and adds to already overburdened waterways.

“At the moment, this the only one (area) we’ve had to evacuate,” he said Sunday morning.

Soon thereafter, residents in Farmington, New Durham, Barrington and Lebanon, Maine, also were evacuated from water-logged areas. Other residents left their flooded homes after power was shut off for safety purposes.

Many residents in those communities also chose to stay with relatives rather than at shelters.

Shelter locations included Barrington Middle School, Nute Middle High School in Milton and Sanford High School in Sanford, Maine. Shelters also were established in Exeter, Newmarket, Kingston and Kensington, according to the American Red Cross.

Individual towns determine when to open a shelter, which are manned by local volunteers and members of the American Red Cross, said Sarah Cherne, Great Bay Chapter executive director.

“We can’t just self-deploy, we need to be called by the towns,” she said, adding that the Red Cross will assess whether more shelters or other services are needed this morning

Many people voluntarily evacuated their homes along the Isinglass River in Barrington after officials released a foot of water from the Bow Lake Dam in Strafford. Residents evacuated from the Strafford town line to Route 202, Barrington Fire Chief Rick Walker said.

Emergency personnel knocked on doors and called more than 150 residents Sunday morning, but it’s unclear how many evacuated. Ten people took shelter at the Barrington Middle School while many others went to stay with family and friends.

Two cats also are being sheltered at town hall. Red Cross representatives are assisting residents at the middle school, and local Boy Scouts came to entertain the group on Sunday and brought games for children.

Barrington Town Administrator Carol Reilly said it was fortunate they contacted people early in the day Sunday because roads were impassable by noon. Some residents were advised to stay put because those roads were impassable, such as on French Mill Road and New Bow Lake Road. Reilly added that some residents left their homes by boat.

Others on Long Shore Road and Berry River Road were told to stay put because of washouts on those roads. Two other homes have become islands on the Isinglass, and town staff are making periodic calls to check on the residents who live there, Walker said.

Evacuating residents became even more difficult later in the day on Sunday because Route 202A became the only evacuation route after Route 202 on the Rochester end was shut down, Reilly added.

Barrington Town Hall was set up as an emergency operation center, which lets it act as a call center. Town staff had compiled a database of residents in potential flood areas using tax maps to help during evacuations.

Walker said police and fire crews are checking on the Isinglass River hourly today, and the town was waiting for news on whether more water would be released later today on Bow Lake Dam, which affects Barrington, Rochester and Dover. Swains Dam is also under close scrutiny by the emergency crews, who have been working since 11 p.m. Saturday.

Road crews also are trying to prevent more roadways from washing out.

“Hopefully Mother Nature will cooperate pretty quick and get this rain slowed down,” Walker said.

Two areas causing Barrington officials most concern are bridges that cross the Isinglass at Greenhill Road and Route 202, Reilly said. Water levels are very high and could cause washouts.

“The source water at Greenhill (Road) also could undermine the integrity of the bridge abutments,” Reilly said.

Depending on how long the rain lasts, the call center at town hall could be in operation through tomorrow, though Reilly said it was too soon to tell. Amazingly, she added, people from all over New Hampshire have been calling the Barrington center to learn if they can get home, if roads were passable and if schools would be open. She said she was referring them to other contacts who could better help them in municipalities such as Manchester, Canaan, Lebanon, Farmington and Rochester.

“People were thankful for the little help we could give,” she said.

During the weekend, Rochester officials were on high alert and notified residents and businesses in affected areas — especially along the Cocheco, Salmon Falls and Isinglass rivers — and warned residents of the potential dangers as a precaution.

Three businesses in the Gonic Mill — Arts Rochester, All Doors and Locks Glass & Mirror and Athletic Innovation — are “completely flooded out” due to rising waters in the Cocheco River, Fire Chief Norm Sanborn said. There is more than a foot of water in the building. Rescue personnel have to wait to move in until the water recedes on its own, Sanborn said.

Sanborn received word around 8:30 a.m. that the East Rochester mill, home to Boston Felt, had 10 inches of water in it.

The first floor of the Wyandotte Mill senior complex, not far from the downtown dam, was evacuated. Some of the residents went to the Roberge Center, officials said.

Residents of Cocheco River Estates and the Chestnut Hill left their homes to be with family and friends elsewhere, Sanborn said. The Rochester Middle School shelter had only two people in it Sunday night.

Emergency crews continue to monitor the Spaulding Fiber Dam on the Salmon Falls River. It’s downstream from the dam in Milton.

Sanborn said the department has responded to “tons and tons” of flooded basements. The Department of Public Works said four roads — part of Salmon Falls Road, Flat Rock Bridge Road, Chesley Hill Road just south of Route 202, and Rochester Neck Road at the Isinglass River either are washed out or impassable because of flooding. About two dozen road shoulders in low-lying areas are also washed out.

City Engineer Tom Willis said he expects a hefty cleanup bill.

“We’re going to have to expend a fair amount of time, money and resources,” Willis said.

While the Three Ponds Dam held much of the waters, Lucier said about 75 percent of the roads in town sustained heavy water damage, making most of them impassible on Sunday. He added that town and school officials, like in many other communities, already decided to postpone school for local students on Monday.

Lucier said despite widespread road problems, there were relatively few accidents, although at least one person fell into trouble after failing to heed road closure signs along Route 75, which connects Milton to Farmington.

“The pavement gave way and it (the car) drove right into it,” Lucier said, adding that firefighters found the car in a large water-made ditch which prevented any access.

No one was injured in the accident.

Lucier said as a result of the floods along Hare Road on Saturday and the washout on Route 75 on Sunday, Farmington firefighters agreed to cover western Milton since local crews could not access that part of town. Though many Middleton roads were cut off or closed down due to water damage on Sunday, about 50 area residents still managed to attend the annual Mother’s Day Breakfast, sponsored by firefighters, who enjoyed a light moment between storm-related chores around town.

As of this morning a section of Silver Street between Maple Road and Sunrise Drive and part of Route 153 near Union hill remain closed.

New Durham Fire Chief John Nicastro III said firefighters and road crews remained busy responding to road-related problems throughout the storm. He added that all of the town’s roads are passable for the moment, but will need more permanent repairs.

“It was a long day — my guys and the highway crews worked really hard,” Nicastro said, adding that local firefighters later responded to Alton to help fill and place sandbags at one of that town’s smaller dams.

Strafford Fire Chief Loren Pierce said it was fortunate that Bow Lake’s water levels had been low prior to the constant rain because it was able to absorb some precipitation before water was released. No residents had to be evacuated in the town, though portions of a couple of roads were closed.

Northwood was not as affected by the heavy rains either, also with only portions of two roads closed.

Staff writers Amanda Dumond, Adam Krauss and Jeremiah Rood contributed to this report.