A June 4 article incorrectly said that the D.C. Water and Sewer Authority added chloramine, a combination of chlorine and ammonia, to treat the drinking water four years ago. Also, a May 24 article incorrectly said that WASA planned to add orthophosphate to the water to solve recent lead leaching problems. The Washington Aqueduct, run by the Army Corps of Engineers, was responsible for both water treatments. (Published 6/8/04)

D.C. Water and Sewer Authority Chairman Glenn S. Gerstell said yesterday that the agency's Board of Directors probably will approve a plan next month to replace the city's estimated 23,000 lead service lines by 2010, at a cost of up to $350 million.

After board members spoke in favor of the plan at their monthly meeting yesterday, Gerstell said in an interview that the policy "is the right course of action," despite concerns by Mayor Anthony A. Williams (D) and water quality experts.

Williams and some engineers and scientists familiar with WASA's water distribution system have said that replacing lead service lines, which is costly and disruptive to city streets, is not necessary to stem the leaching of lead into the water.

This month, officials at the Washington Aqueduct began adding orthophosphate to the water in part of the distribution system. If there are no problems, orthophosphate will be added to the entire system next month in hopes of coating the pipes and stemming the leaching. WASA has found excessive lead levels in the water of thousands of city homes.

Despite that, Gerstell said WASA's board believes that getting as much lead as possible out of the distribution system will help prevent similar problems in the future.

"Even though we have unanswered questions, a responsible course of action is to go ahead and forge new ground and recognize that in the nation's capital we should lead the way and take the extra step despite the cost and uncertainty," Gerstell said.

D.C. Council members Carol Schwartz (R-At Large), Adrian M. Fenty (D-Ward 4) and Jim Graham (D-Ward 1), said yesterday that they support the plan.

"We know lead pipes cause a problem," Schwartz said. "Let's get rid of them."

WASA would pay for the replacement program through its capital budget, possibly deferring other projects or raising water rates to pay for debt service on new bonds, WASA General Manager Jerry N. Johnson has said. Some city leaders have called on the federal government to contribute money because the lead pipes were installed decades ago when federal officials ran the city.

In April, Williams cautioned that removing all lead service lines might not be wise without first learning of "best practices" used by other cities. Although some cities have decided to remove all their lead service lines, others have tried to control leaching through chemical treatment of the water.

Williams's spokesman, Tony Bullock, said yesterday that the mayor still has concerns.

"The disruption to traffic and people's property, the endless jack-hammering and street closings could really be disruptive," Bullock said. "It's premature to make a hard commitment to that total replacement. A smarter course would be to see how the orthophosphate works."

In the District, as in many cities, the water utility owns the portion of the service line that runs from the water main to the property line of each home. Residents would therefore be responsible for replacing their portion of the service line, which could cost more than $3,000 in some cases.

Studies have shown that replacing only part of a lead service line could actually make the problem worse because flakes of lead can fall off where the copper and lead pipes are joined.

Council member Harold Brazil (D-At Large) has offered legislation that would help homeowners pay for such work, but no specific amount of money has been made available by the city.

The WASA board also voted to set a fixed rate for homeowners who want a WASA contractor to replace lines on private property. The proposed rate would be $100 per linear foot for the line outside the home and a $500 fee for replacing the line from the point of entry outside the house to the plumbing inside.

Some estimates have put the number of lead service lines at 23,000, but there could be thousands more. WASA's records, some dating back more than 100 years, are incomplete.

Erik Olson, a lawyer for the Natural Resources Defense Council, said his organization supports WASA's plan to replace the lead service lines. Relying simply on changing the water chemistry to control lead leaching is just as uncertain a prospect, Olson said.

Four years ago, for example, WASA began adding a chemical called chloramine -- a combination of chlorine and ammonia -- to control possible carcinogenic byproducts. Now agency engineers believe that chemical could have contributed to the lead problems.

WASA Chairman Glenn S. Gerstell calls removing lead pipes "the right course of action."