The Maryland Senate barely mustered the votes for a bill to require Maryland homeowners living within 1,000 feet of the Chesapeake Bay to install environmentally friendly sewage systems when current ones fail. The 24-23 vote came after a contentious debate. Opponents say the nitrogen removal technology the bill requires will put an unfair burden on residents who could have trouble affording the sewage systems. Supporters say the measure is needed to clean up nitrogen pollution in the nation’s largest estuary.