Lead is unusual among drinking water contaminants in that it seldom occurs naturally in source water supplies like rivers and lakes. Rather, lead enters drinking water primarily as a result of the corrosion of materials containing lead in the water distribution system and in household plumbing. These materials include lead service pipes that connect a house to the water main, household lead-based solder used to join copper pipe, and brass plumbing fixtures such as faucets. The Safe Drinking Water Act is the key federal law protecting public water supplies from harmful contaminants. The Act established a federal-state arrangement in which states may be delegated primary implementation and enforcement authority (“primacy”) for the drinking water program. Except for Wyoming and the District of Columbia, all states and territories have received primacy. For contaminants that are known or anticipated to occur in public water systems and that the EPA Administrator determines may have an adverse impact on health, the Act requires EPA to set a non- enforceable maximum contaminant level goal (MCLG) at which no known or anticipated adverse health effects occur and that allows an adequate margin of safety. Once the MCLG is established, EPA sets an enforceable standard for water as it leaves the treatment plant, the maximum contaminant level (MCL). The MCL generally must be set as close to the MCLG as is “feasible” using the best technology or other means available, taking costs into consideration. The fact that lead contamination occurs after water leaves the treatment plant has complicated efforts to regulate it in the same way as most contaminants. In 1975, EPA set an interim MCL for lead at 50 parts per billion (ppb), but did not require sampling of tap water to show compliance with the standard. Rather, the standard had to be met at the water system before the water was distributed. The 1986 amendments to the Act directed EPA to issue a new lead regulation, and in 1991, EPA adopted the Lead and Copper Rule. Instead of an MCL, the rule established an “action level” of 15 ppb for lead in drinking water, and required that water systems take steps to limit the corrosiveness of their water. Under the rule, the action level is exceeded if lead levels are higher than 15 ppb in over 10 percent of tap water samples taken. Large systems, including WASA, generally must take at least 100 tap water samples in a 6-month monitoring period. Large systems that do not exceed the action level or that maintain optimal corrosion control for two consecutive 6-month periods may reduce the number of sampling sites to 50 sites and reduce collection frequency to once per year. If a water system exceeds the action level, other regulatory requirements are triggered. The water system must intensify tap water sampling, take additional actions to control corrosion, and educate the public about steps they should take to protect themselves from lead exposure. If the problem is not abated, the water system must annually replace 7 percent of the lead service lines under its ownership. The public notification requirements of the Safe Drinking Water Act are intended to protect public health, build trust with consumers through open and honest sharing of information, and establish an ongoing, positive relationship with the community. While public notification provisions were included in the original Act, concerns have been raised for many years about the way public water systems notify the public regarding health threats posed by contaminated drinking water. In 1992, for example, we reported, among other things, that (1) there were high rates of noncompliance among water systems with the public notification regulations in effect at that time and (2) notices often did not clearly convey the appropriate information to the public concerning the health risks associated with a violation and the preventive action to be taken. The 1996 Amendments to the Safe Drinking Water Act attempted to address many of these concerns by requiring that consumers of public water supplies be given more accurate and timely information about violations and that this information be in a form that is more understandable and useful. Drinking water is provided to District of Columbia residents under a unique organizational structure: The U.S. Army Corps of Engineers’ Washington Aqueduct draws water from the Potomac River and filters and chemically treats it to meet EPA specifications. The Aqueduct produces drinking water for approximately 1 million citizens living, working, or visiting in the District of Columbia, Arlington County, Virginia, and the City of Falls Church, Virginia. Managed by the Corps of Engineers’ Baltimore District, the Aqueduct is a federally owned and operated public water supply agency that produces an average of 180 million gallons of water per day at two treatment plants located in the District. All funding for operations, maintenance, and capital improvements comes from revenue generated by selling drinking water to the District of Columbia, Arlington County, Virginia, and the City of Falls Church, Virginia. The District of Columbia Water and Sewer Authority buys its drinking water from the Aqueduct. WASA distributes drinking water through 1,300 miles of water mains under the streets of the District to individual homes and buildings, as well as to several federal facilities directly across the Potomac River in Virginia. From its inception in 1938 until 1996, WASA’s predecessor, the District of Columbia Water and Sewer Utility Administration, was a part of the District’s government. In 1996, WASA was established by District of Columbia law as a semiautonomous regional entity. WASA develops its own budget, which is incorporated into the District’s budget and then forwarded to Congress. All funding for operations, improvements, and debt financing come from usage fees, EPA grants, and the sale of revenue bonds. EPA’s Philadelphia Regional Office has primary oversight and enforcement responsibility for public water systems in the District. According to EPA, the Regional Office’s oversight and enforcement responsibilities include providing technical assistance to the water suppliers on how to comply with federal regulations; ensuring that the suppliers report the monitoring results to EPA by the required deadlines; taking enforcement actions if violations occur; and using those enforcement actions to return the system to compliance in a timely fashion. The District’s Department of Health, while having no formal role under the Act, is responsible for identifying health risks and educating the public on those risks. Providing safe drinking water requires that water systems, regulators, and public health agencies fulfill individual responsibilities yet work together in a coordinated fashion. It is particularly important that these entities report and communicate information to each other in a timely and accurate manner. In the case of drinking water in the District of Columbia, one of the key relationships is the one between WASA, the deliverer of water to District customers, and EPA’s Philadelphia Office, the regulator charged with overseeing WASA’s compliance with drinking water regulations. Of particular note, one of WASA’s key obligations is to monitor the water it supplies to District customers through a tap water sampling program, and to report these results accurately and in a timely manner to EPA’s Philadelphia Office. As EPA itself has noted, one of the Philadelphia Office’s key obligations is to ensure that WASA understands the reporting requirements and reports monitoring results by required deadlines. It is noteworthy that WASA and EPA have taken or agreed to take steps that are clearly intended to improve communication and coordination between the agencies. For example: Under the Consent Order signed by EPA and WASA on June 17, 2004, WASA agreed to improve its format for reporting tap water samples by ensuring that the reports include tap water sample identification numbers, sample date and location, lead and copper concentration, service line materials, and reasons for any deviation from previously sampled locations. The monitoring reports are also to include the laboratory data sheets, which contain the raw test data recorded directly by the laboratory. Under the Order, WASA also agreed to submit to EPA for comment a plan and schedule for enhanced information, database management, and reporting. The plan is to describe how monitoring reports will be generated, maintained, and submitted to EPA in a timely fashion. EPA’s Philadelphia Office has altered the way in which it will handle compliance data from WASA and the Washington Aqueduct. According to the office, compliance data from both water systems will now be sent to those in the Office responsible for enforcing the Safe Drinking Water Act, so as to separate the enforcement/compliance assurance function from the municipal assistance function. Aside from the tap water monitoring issue, EPA’s Philadelphia Office acknowledges that its oversight of WASA public notification and education efforts could have been better, noting that “In hindsight, EPA should have asked more questions about the extent, coverage and impact of DC WASA’s public education program, and reacted to fill the public education gaps where they were evident.” To address the problem, the Philadelphia Office reported on its website that it will have to make some improvements in the way it exercises its own oversight responsibilities. Suggested improvements include obtaining written agreement from WASA to receive drafts of education materials and a timeline for their submission, reviewing drafts of public education materials for compliance with requirements, as well as effectiveness of materials and delivery, and acquiring outside expertise to assist in evaluating outreach efforts. As our work continues, we will seek to examine (to the extent it does not conflict with active litigation) other ways in which improved coordination between WASA and EPA could help both agencies better fulfill their responsibilities. We will also examine interrelationships that include other key agencies, such as the Aqueduct and the D.C. Department of Health. We will also examine how other water systems in similar situations interacted with federal, state, and local agencies. These experiences may offer suggestions on how coordination can be improved among the agencies responsible for protecting drinking water in the District of Columbia. WASA is not the first system to exceed the action level for lead. According to EPA, when the first round of monitoring results was completed for large water systems in 1991 pursuant to the Lead and Copper Rule, 130 of the 660 systems serving populations over 50,000 exceeded the action level for lead. EPA data show that since the monitoring period ending in 2000, 27 such systems have exceeded the action level.