The purpose of the project is to compile extensive existing data and provide a comprehensive analysis of channel mercury (Hg) load response to various proposed management scenarios in order to determine the most cost effective method for achieving Guadalupe River TMDL Hg load reduction goals. If such modeling is not completed there is a greater risk that expenditure of public funds will not result in desirable load reductions or that expectations for a trend in the system in response to management may be unrealistic leading to disappointment and perhaps discontinuation of management activities that are in fact beneficial. This project will:
1. Develop a comprehensive water quality model based on a calibrated and verified hydrologic model using the BASINS/HSPF (v. 3) modeling suite recommended by the EPA. 2. Use this model to test combinations of feasible management scenarios to assist stakeholders in the prioritization of activities and the level of effort required to meet the 10 and 20 year load reduction targets. Specific questions include: Q1. What influence will the various management options (sediment dredging, channel modifications, reservoir management, hot-spot removal in tributaries and mining areas) have on concentrations and loads? Q2. What the differing influences on grainsize and quality are of suspended and bed sediment? Q3. How long will it take to see a trend and will this trend be sufficient to meet the proposed 10 year loading target (11 kg/y) and the 20 year loading target (7 kg/y)? 3. Provide a completed watershed module ready for inclusion into future modeling of the south Bay salt pond restoration project areas (e.g. Pont A8). Note the proposed modeling component will not model processes in the tidal portions of Alviso Slough or within restoration ponds.
The purpose of the project is to provide a comprehensive analysis of channel and mercury (Hg) load response to various proposed management scenarios in order to determine the most cost effective method for achieving TMDL Hg load reduction goals. Guadalupe River and a number of it tributaries and reservoirs are on the 303(d) list of impaired water bodies for Hg. The draft Guadalupe River Watershed Hg TMDL just released for public review (Austin, 2006) prescribes load allocations for Hg and calls for a substantial reduction of Hg loads in urban and mining runoff over 10 and 20 years. In order to meet these management targets, a number of measures have been proposed including removal of sediment from channels, further mitigation of mine waste, application of urban BMPs, and changes to reservoir management, however it is not clear how effective these initiatives will be and how long it will take for load reductions to be realized. In addition to efforts to manage Hg in the watershed, there is a developing need to understand and manage fluxes of Hg in the large wetland restoration project area in the receiving water bodies downstream (Alviso Slough and adjacent former salt ponds, e.g. A8). A current weakness in the TMDL is the lack of a comprehensive model to decipher complex Hg sources-release, transport-transformation, and loading processes. Numeric models provide an ideal framework for data compilation and interpretation and can be used to develop, test and prioritize management options for control of NPS pollution, guide further targeted data collection, reduce redundancy, and achieve TMDL goals. The goal of this project is to build upon existing District modeling and develop a mercury module to test a variety of management scenarios. If such modeling is not completed there is a greater risk that public funds spent will not result in desirable load reductions or that expectations for a trend in the system in response to management may be unrealistic.
Watershed Management, Technical Analysis, stakeholder involvement, Funding/Financing, Water Quality, Bay Area Water Supply and Conservation Agency, Rivers, Data Management
Ecosystem Restoration,
Environmental and habitat protection and improvement,
Land use planning,
NPS pollution control,
Recreation and public access,
Water quality protection and improvement,
Watershed planning
