Incumbant Ward 1 Council member Jim Graham greets volunteers and supporters at Haydees restaurant in Mount Pleasant on Tuesday. (Evelyn Hockstein/ The Washington Post)

Community activist Brianne Nadeau has defeated incumbent Jim Graham in the D.C. Council Ward 1 race, ending his 15 years of service in a rapidly changing corner of the city after a nasty campaign that featured dueling accusations of ethical lapses.

“We are really excited about the opportunity to serve Ward 1,” Nadeau said late Tuesday. “It’s been a long campaign.”

In the at-large contest in the Democratic primary, incumbent Anita D. Bonds held onto her seat with a commanding victory. Although she has been in the post for only 15 months, Bonds won by a more than two-to-one margin over her nearest challenger, Nate Bennett-Fleming.

And in the third competitive Council race of the reason, Charles Allen overwhelmingly defeated Darrel Thompson in the Ward 6 contest to replace Tommy Wells (D), who gave up a chance at re-election to run for mayor. Wells came in third place Tuesday, after Muriel Bowser and incumbent Vincent C. Gray.

All results are based on numbers posted by the D.C. Board of Elections, which shows 100 percent of precincts reported across the city.

Brianne Nadeau poses for a photo inside her campaign headquarters on 14th Street. (Astrid Riecken/The Washington Post )

In Ward 1, Graham, a four-term incumbent, struggled to weather the ethical issues that had dogged him for the past two years. In the end, Nadeau, a former Advisory Neighborhood Commission member, surged from a thicket of potential candidates.

Questions about Graham’s conduct began circulating in 2012, when he was found to have improperly intervened in a Metro contract on behalf of a campaign contributor. In the case, an independent investigation found that Graham “acted in a manner contrary to Metro’s standard of conduct” when he tried to persuade a businessman to withdraw from a development project. In exchange, investigators found, Graham promised to support the businessman’s bid for a D.C. lottery contract.

In February 2013, a D.C. ethics board considered the same matter and found that Graham “engaged in conduct that adversely affected the public confidence in the integrity of government.” Even so, the board said it had no authority to sanction Graham because the contract was from 2008 — outside the board’s mandate to impose penalties.

The D.C. Council reprimanded Graham after the ethics board’s report; the council also revoked some of his powers over alcohol issues as head of a council committee. Graham became the second council member under home rule to be reprimanded by his colleagues; Marion Barry faced a censure from the council in 2010.

In the days leading up to the primary, Graham questioned the size of his opponent’s interest-free home loan. He alleged that Nadeau, a public relations consultant, solicited and received special consideration for a loan to buy her Northwest Washington condominium.

Council members Wells and David Grosso (I-At Large) endorsed Nadeau’s candidacy, a rare move by council members, who usually stay out of competitive contests.

With Wells running for mayor, the race for the Ward 6 seat pitted Allen and Thompson, two relative newcomers.

Both brought previous experience in government: Allen is Wells’s former chief of staff and Thompson is a former deputy chief of staff to Senate Majority Leader Harry M. Reid (D-Nev.).

Both Allen and Thompson promised to improve the condition of schools and provide more affordable housing for young families and older residents.

Allen’s supporters said Thompson’s national exposure is impressive but did not trump Allen’s knowledge of Ward 6 constituents. Thompson raised more than $196,000 for the contest.

In the race for the at-large seat, Bonds faced Bennett-Fleming as well as John F. Settles II and Pedro Rubio. Bonds, 68, held the seat vacated by Phil Mendelson when he became council chairman.

Bonds sponsored the Senior Citizen Real Property Tax Relief Act of 2014, which Gray (D) signed into law in March. But her detractors accused her of not doing enough beyond that measure.

Mendelson, who was opposed by Calvin Gurley for chairman, handily won re-election Tuesday.

In Ward 5, incumbent Kenyan McDuffie won nearly 80 percent of the vote in his race with Kathy Henderson and Carolyn C. Steptoe.

And in Ward 3, Mary Cheh was unopposed.