A project located at the VPI & SU Swine Center was used to investigate the utilization of a waste treatment lagoon as an energy source to heat swine housing. The investigation test procedure consisted of two main components: (1) the design and testing of a heating system using a solar assisted heat pump and (2) the development of a computer model to simulate lagoon response to energy gains and losses. The energy lost by the lagoon was considered to occur by conduction, convection, evaporation and radiation. Under natural weather conditions, the losses due to these factors become gains when the lagoon temperature is less than the temperature of the surrounding earth and air. Energy gain by the lagoon under most operating conditions was due to solar insolation. By using the information generated by the computer model and data collected during the testing of the system, it was concluded that there is low level energy available in the waste treatment lagoon. Also, the removal of the low level energy for heating swine housing has little effect upon the thermal stability of the lagoon. / Master of Science