The Iowa Code sections 455B.113 through 455B.115 require certification of laboratories performing analyses of samples which are required to be submitted to the Iowa Department of Natural Resources (IDNR). The rules detail the requirements of the laboratory certification program and will eventually include all sample analyses required to be submitted to the IDNR. Certification of laboratories for analysis of solid waste and contaminated site program samples began in 2004. The certification program applies to laboratory analytical methods for analysis of water, soil, or solid samples for the Solid Waste or Contaminated Sites programs. With the new rules effective 2/11/2004, the IDNR groups the SW/CS parameters into three analyte groups for the purpose of certification. Solid Waste or Contaminated Sites r laboratory certification is performed in accordance with the, Manual for the Certification of Laboratories Analyzing Environmental Samples for the Iowa Department of Natural Resources , Criteria and Procedures, Quality Assurance, Chapter 4 (August 2003). This document lists and discusses the evaluation factors and states the criteria that will be used for evaluation of laboratories seeking certification in Iowa for provision of Wastewater program data to IDNR. Laboratories are required to perform satisfactorily on a blind proficiency evaluation study annually.