The requirements for a wastewater treatment plant microcomputer based Laboratory and Operations Information System (LOIS) were considered. Emphasis was placed on combining data generated by the laboratory and the operations divisions of the Alexandria Sanitation Authority. Goals were established to meet the information needs of key decision makers within the Authority and external information consumers such as regulatory authorities and design engineers. Integration of laboratory analysis and plant operational data was of prime importance. A series of related computer programs was developed to manage laboratory and operational data and calculate results derived from both sources. The programs stressed data integrity, flexible report generation, statistical and graphical data analysis, and ease of use. A program was developed to address laboratory quality control data management and the production of quality control charts. The computer programs were written in a generic fashion so as to be applicable to other water or wastewater treatment plants and to provide maximum flexibility for future expansion. Programs were developed in a modular fashion to allow greater ease of maintenance and revision in the future. Common subroutines were employed wherever possible. Some report generation subprograms were written specifically to the requirements of the Alexandria Sanitation Authority. / Master of Science