Lawrence Berkeley National Laboratory

Seasonally managed wetlands in the Grasslands Basin of California's San Joaquin Valley provide food and shelter for migratory wildfowl during winter months and sport for waterfowl hunters during the annual duck season. Surface water supply to these wetland contain salt which, when drained to the San Joaquin River during the annual drawdown period, negatively impacts downstream agricultural riparian water diverters. Recent environmental regulation, limiting discharges salinity to the San Joaquin River and primarily targeting agricultural non-point sources, now addresses return flows from seasonally managed wetlands. Real-time water quality management has been advocated as a means of matching wetland return flows to the assimilative capacity of the San Joaquin River. Past attempts to build environmental monitoring and decision support systems to implement this concept have failed for reasons that are discussed in this paper. These reasons are discussed in the context of more general challenges facing the successful implementation of environmental monitoring, modelling and decision support systems. The paper then provides details of a current research and development project which will ultimately provide wetland managers with the means of matching salt exports with the available assimilative capacity of the San Joaquin River, when fully implemented. Manipulation of the traditional wetland drawdown comes at a potential cost to the sustainability of optimal wetland moist soil plant habitat in these wetlands - hence the project provides appropriate data and a feedback and response mechanism for wetland managers to balance improvements to San Joaquin River quality with internally-generated information on the health of the wetland resource. The author concludes the paper by arguing that the architecture of the current project decision support system, when coupled with recent advances in environmental data acquisition, data processing and information dissemination technology, holds significant promise to address some of the problems described earlier in the paper that have limited past efforts to improve Basin water quality management.