PROJECT SUMMARY The hydroecological characterization of Arroyo Alamar, in Tijuana, Baja California, Mexico, will be accomplished. The project will rehabilitate the stream channel to enable a seamless interaction of diverse stream functions and uses, including flood mitigation, groundwater replenishment, preservation of riparian corridors, enhancement of water quality, satisfaction of federal stream zoning restrictions, and multipurpose land use such as agriculture, light industry, recreation, urban landscaping, and ecotourism. The characterization will use design flood discharges obtained in a previous SCERP-funded project to provide a multi-terraced channel within a planned environment. Examples of successful hydroecological rehabilitation of the Rio Atoyac, in Oaxaca, Mexico, and elsewhere will be used as guidelines. The study will use the U.S. Army Corps of Engineers Hydrologic Engineering Center's River Analysis System (HEC-RAS), a federally funded model which calculates flood stages. One-hundred transects will be used to assure the accuracy of horizontal and vertical coordinates, variability in friction coefficients, and bank stability. The design will be based on sound hydroecological principles, which aim to maximize natural components and features. The outcome will be a design for Arroyo Alamar which properly accounts for relevant hydrological, ecological, and environmental aspects. The results will be used by the Municipality of Tijuana to carry out the project to its financing and construction stages. The project will replace the existing condition, which is substandard and a recognized health hazard. Once implemented, the Arroyo Alamar rehabilitation project will be an architectural and lanscape feature that the city is certain to be proud of.