RBI led the preparation of the hydrology, water quality, and aquatic biological resources sections of the Environmental Impact Report (EIR) evaluating the Sacramento Regional County Sanitation District’s proposed EchoWater Project, on a project team with Ascent Environmental as the lead EIR preparer. The project would improve the quality of effluent discharged from the Sacramento Regional Wastewater Treatment Plant. RBI assessed the effects of the discharge under four different alternatives, each with different effluent quality, on the Sacramento River and Sacramento-San Joaquin Delta. The water quality assessment evaluated the discharge of priority pollutants, nutrients, salinity-related parameters, and total organic carbon. The aquatic biological resources assessment evaluated effects of the thermal plume created by the discharge on benthic macroinvertebrates, drifting plankton, and resident and anadromous fish in the Sacramento River. Thermal effects to lower Sacramento River and Delta aquatic life upon full mixing of effluent discharges with river flows also was assessed. The project involved extensive coordination with the project team, including District personnel, CEQA legal team, and technical team members conducting hydraulics, hydrologic, and water quality modeling.