“The rest of the river could have been heavily impacted by it,’’ said Michele Grzenda, Weston’s conservation agent. “There could have been a number of effects. For example, the habitat for the fish in the area could have been severely impaired as a result of the sediment entering the river. The river definitely needed to be restored . . . as soon as possible.’’

The break in the 10-foot-diameter pipe carrying water from Central Massachusetts to the Boston area forced the Massachusetts Water Resources Authority to shift to a backup system, and a boil-water order was issued for 2 million area residents, a disruption that lasted 2 1/2 days.

While the water gushing from the underground pipe alongside the Charles was stanched fairly quickly, nearby Weston residents, conservationists, and MWRA officials alike knew something had to be done to repair the damage caused by the millions of gallons of water and eroded material that had flooded into the river after the May 1 rupture.

Almost immediately, the MWRA and the Weston Conservation Commission moved to assuage the impact of the sandbar that formed roughly 200 feet from the site of the break.

It took about a month to remove the bar and restore the site, though work to replace vegetation continues.

The MWRA’s executive director, Fred Laskey, said that leaving it in the river was not an option.

“It was absolutely critical that we removed the sandbar as quickly as possible,’’ he said. “The flow of the river could have been changed if we left it in there. That could have impacted boating in the river. Erosion could have also been caused as a result from the change in water flow. It was important to remove the sand bar in a speedy fashion.”

About $200,000 was spent to remove the sandbar and restore the affected area, Laskey said.

But the work is not over.

Grzenda said vegetation will be closely monitored for the next two growing seasons, and additional sediment clumps may be removed from the river.

The sandbar was created when a large amount of soil, gravel, and other materials was carried into the river by the force of the water flowing from the broken main and over an embankment. As a result, the materials settled in the river, forming the sandbar.

According to Grzenda, the sandbar was about 150 feet long and 50 feet wide, and was 8 feet thick in some places.

“It was a pretty dramatic sight to see,’’ said Grzenda, adding that it was the single biggest impact she had seen to the river during her tenure in Weston.

Work to remove the sandbar began less than a week after the water-main break. Before the material was removed, a silt curtain was established around the perimeter to prevent additional sediment from flowing into the water. And because the area was wooded, the MWRA had to clear vegetation to gain access with their equipment.

The MWRA worked on the excavation of the bar and the restoration of the site, Grzenda said, and the Conservation Commission oversaw the work, making sure the Charles River was not damaged any further.

She said the Conservation Commission was very pleased with the MWRA’s swift response to the sandbar.

“It was great that the MWRA worked so quickly with everything that was going on at the time,’’ said Grzenda.

“They were on such a rigorous schedule, as they were also trying to correct everything that was going on with the water main break at the same time,’’ she said, and noted that the MWRA “worked so hard to restore the river back to where it was before this all happened.’’

The excavation of the sandbar took less than two weeks, according to Grzenda.

The MWRA then submitted a restoration plan for the surrounding area. After the agency’s plan was accepted, the restoration, which included adding vegetation and erosion controls, took just over two weeks.

Nearby residents say they are encouraged by the restoration work, considering the potential damage to the Charles River ecosystem.

“I think it’s a relief that the MWRA was able to respond so quickly,’’ said Ana Carolina Gomez, who lives near the river. “It’s really great to know that they were able to restore the river, not just to remove the sandbar itself, but also to protect the environment, too.’’