The regulation for the first cycle of the Unregulated Contaminant Monitoring Rule (UCMR 1), covering the period 2001 - 2005, was published in the Federal Register September 17, 1999 for a list of 26 contaminants. UCMR1 was a redesign of the original UCM Program, and incorporated a tiered monitoring approach along with EPA implementation. UCMR1 had Assessment Monitoring (List 1) and Screening Survey (List 2) components.

• Federal Register September 17, 1999

Assessment Monitoring was conducted by large public water systems (PWSs) serving more than 10,000 people, and 800 representative small PWSs serving 10,000 or fewer people, for 12 List 1 contaminants. These contaminants were measured with analytical method technologies in common use by drinking water laboratories. Assessment Monitoring was conducted by each PWS over a 12-month period between 2001 and 2003.

Screening Survey monitoring was conducted by a randomly selected set of 300 large and small PWSs. There were 13 organic chemicals and one microorganism that were monitored for List 2 Screening Survey. Screening Survey monitoring for chemical contaminants was conducted in 2001 at selected small PWSs and in 2002 at selected large PWSs. Screening Survey monitoring for the List 2 microorganism, Aeromonas, was conducted in 2003 for both large and small selected systems.

• Fact Sheet - Basic information on UCMR 1 and fact sheets on aspects of the rule
• Regulation - Regulations associated with UCMR 1
• Contaminant List - Contaminants monitored under UCMR 1
• Water Systems - Drinking water utilities participating in UCMR 1 monitoring
• Laboratories - Laboratories approved to carry out analyses under UCMR 1
• Guidance - Guidance and technical documents that explain the rule
• Methods - Approved analytical methods for contaminants in UCMR 1
• Reporting - Portal for electronic reporting and approving analytical results
• Updates - Information for utilities and laboratories participating in monitoring
• Meetings & Materials - Materials from meetings held on UCMR 1 issues
• Occurrence Data - UCMR data from all rounds of monitoring