IERCA operates the largest indoor biosolids composting facility in the USA. It produces a wood-based, nutrient-rich compost, made from recycled green waste, biosolids and horse-stable bedding. IERCA was created by a Joint Powers Agreement (JPA) between the  Inland Empire Utilities Agency (IEUA) and County Sanitation Districts  of LA County (CSDLAC).
This agreement empowered both IEUA and CSDLAC  to acquire, construct, operate and maintain a composting facility. IEUA and CSDLAC have jointly evaluated composting as an economically and environmentally sound method of beneficially reusing biosolids that are generated from the wastewater treatment facilities operated by each.