Research and Development Office

An Integrated Modeling Tool to Assess Mercury Transport and Transformation Processes at Reservoirs

Project ID: 3425
Principal Investigator: Yong Lai
Research Topic: Water Quality
Funded Fiscal Years: 2015, 2016 and 2017
Keywords: methylmercury control, water quality in reservoir, integrated modeling tool for mercury

Research Question

This research is an outcome of the 2014 USBR-USACE Research Workshop. An urgent research need was raised by Jobaid Kabir (MP Region, Reclamation) about mercury control at Reclamation reservoirs; and USACE has expressed strong interest in collaboration with Reclamation to incorporate USACE's water quality and mercury modules into Reclamation SRH-2D model. A multi-agency team is thus formed to adress the mercury issue leading to this reserach proposal.

Mercury is a toxic metal that is found both naturally and as an introduced contaminant in an aquatic environment. Methylmercury (MeHg) is the most toxic form. Presence of MeHg in many western reservoirs has led to the identification of state-level water quality standards and control programs, e.g., in California, Oregon and Washington. Reclamation will be required to comply with these new standards and they need to develop and implement various reservoir mercury management practices. However, there is currently no standard for such management practices. Research has indicated that each aquatic environment should be evaluated individually because similar conditions in separate reservoirs have been shown to produce different rates of mercury bioaccumulation. Untested management practices may be ineffective at providing the appropriate level of mitigation and can be cost prohibitive for large reservoir operators at Reclamation.

In this study, we propose to develop an integrated mercury transport and transformation modeling tool, involving hydrodynamic, sediment and water quality, to answer the following questions:

(1) Can a reliable integrated mercury dynamic model be developed that will allow Reclamation to assess the feasibility and effectiveness of mercury management measures in its facilities?
(2) What factors (temperature, nutrients, organisms, etc.) control the MeHg process?
(3) What are the factors that govern the mercury cycle in a particular reservoir environment?

Need and Benefit

Methylmercury in reservoirs is becoming an urgent water quality issue for Reclamation since state water quality regulatory agencies have established water quality standards for mercury in many states such as California, Oregon, Washington, Colorado, and many other states. Enforcement of the mercury water quality standard varies by state but Reclamation will be required to comply with the new standards. Some states choose to mandate management practices while others choose collaborative approaches. The State of California, for example, has performed an extensive research and is using the research to develop and encourage mercury management practices as a part of the TMDL development process. A number of Reclamation reservoirs have been on the list in California which need future actions for mercury mitigatyion.

A number of current research projects have demonstrated that some management practices may lead to MeHg reduction, but that there is no standard for reservoir environment. Research has also indicated that each aquatic environment should be evaluated individually; similar conditions in separate reservoirs have been shown to produce different rates of mercury bioaccumulation. On the one hand, current management practices can be cost prohibitive for Reclamation and other large reservoir operators within the state. On the other hand, even if they are implemented, the success of providing the appropriate level of mitigation in Reclamation facilities is uncertain since these practices have not been tested and researched.

There is an urgent need at the Reclamation-wide level to have access to a reliable mercury model that may be used to assess the feasibility of mercury management measures at each specfic Reclamation reservoirs. Without a means to evaluate reservoir mercury processes Reclamation may be forced to implement unreasonable mercury control practices. In the Mid-Pacific Region, for example, the need has been identified to develop a framework for decision making related to mercury management in reservoirs. This research will assist in finding the most efficient and cost effective solutions. At the present, a reliable modeling tool to assess methylmercury processes is the best alternative. A modeling tool may benefit the reservoir managers and operators to answer the question of whether reservoir operational changes can be developed to reduce mercury methylation.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

An Integrated Modeling Tool to Assess Mercury Transport and Transformation Processes at Reservoirs (final, PDF, 3.7MB)
By Yong G. Lai
Research Product completed on September 30, 2017

An Integrated Modeling Tool to Assess Mercury Transport and Transformation Processes at Reservoirs (final, PDF, 4.6MB)
By Yong G. Lai
Research Product completed on September 30, 2017

An Integrated Modeling Tool to Assess Mercury Transport and Transformation Processes at Reservoirs (final, PDF, 3.7MB)
By Yong G. Lai
Research Product completed on September 30, 2017

An Integrated Modeling Tool to Assess Mercury Transport and Transformation Processes at Reservoirs (final, PDF, 4.6MB)
By Yong G. Lai
Research Product completed on September 30, 2017

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