Strategy for Resolving MeHg and Low Dissolved Oxygen Events - Northern Suisun Marsh, 2007 - 2011

Project Description

The 116,000-acre Suisun Marsh is the largest contiguous brackish water marsh remaining on North America’s west coast and is a critical component of the San Francisco Bay-Delta estuary ecosystem. Almost half of the marsh is comprised of managed wetlands that experience seasonal flood-drain-flood cycles depending on environmental conditions and property manager objectives. In northwestern areas of the Marsh, fall flooding cycles cause severe drops in dissolved oxygen (DO) concentrations. Low DO plumes impact aquatic ecosystems, killing at-risk fish species and impairing valuable fish nursery habitat. The low DO may lead to elevated levels of methylated mercury (MeHg) and dissolved organic carbon (DOC), both linked to ecological and human health concerns.

The study (1) identified processes and practices that drive severely low DO events and produce MeHg and DOC in managed wetlands, (2) tested new management practices to mitigate poor water quality conditions, and (3) assessed Best Management Practices for the broader managed wetlands community in Suisun Marsh. To achieve these goals, Bachand & Associates partnered with a broad stakeholder group. The collaborative nature of this demonstration project allowed for robust data collection, including continuous water quality monitoring, discrete water quality sampling, soil and vegetation analyses, and aquatic toxicology measurements. Our findings aid regulatory agencies in developing policies that concurrently improve management strategies and environmental quality in the Suisun Marsh and the greater Bay Area.

Publications and Final Reports

Siegel, S., P. Bachand, D. Gillenwater, S. Chappell, B. Wickland, O. Rocha, M. Stephenson, W. Hei, C. Enright, P. Moyle, P. Crain, B. Downing. B. Bergamaschi. 2011. Final Evaluation Memorandum, Strategies for Resolving Low Dissolved Oxygen and Methylmercury Events in Northern Suisun Marsh. Prepared for the State Water Resources Control Board, Sacramento, California. SWRCB Project Number 06 283 552 0. May. Available on AquaDocs, Published: 2011.

Siegel, S., P. Bachand, D. Gillenwater, S. Chappell, B. Wickland, O. Rocha, M. Stephenson, W. Heim, C. Enright, P. Moyle, P. Crain, B. Downing. B. Bergamaschi. 2011. Best Management Practices Report , Strategies for Resolving Low Dissolved Oxygen and Methylmercury Events in Northern Suisun Marsh. Prepared for the State Water Resources Control Board, Sacramento, California. SWRCB Project Number 06 283552 0. July. Available on CA. State Water Resources Control Board, Published: 2013.