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Western Geographic Science Center (WGSC) OFFSET RESEARCH GUIDANCE
The following section provides general guidance from the WGSC for researching the feasibility of offsets and other water-quality market-based programs for meeting mercury TMDLs and discharge-permit requirements.
The purpose of the following checklist is to provide decisionmakers with a list of questions regarding environmental and implementation concerns and sources that may provide guidance to addressing some of these concerns. A yes/no answer for each of these questions does not imply that an offset is feasible or not but only serves to highlight some of the outstanding uncertainties of mercury fate and transport, methylation, bioavailability, trophic transfer, and implementation issues.
A. Environmental Assessment
1. Fate and Transport Modeling/Source Assessment
| Concern |
Source |
| Are the contributions from [(atmospheric deposition) (geothermal springs) (NPDES dischargers) (soil erosion) (mercury/gold mines) (benthic sediments] loading significant? |
Scientists |
| Can any of these significant loadings capable be reduced? |
Scientists |
| Are there any positive impacts from reducing these loadings? |
Scientists |
| Can we model mercury transport from sources to depositional environments? |
Modelers |
| Can we model chemical transformations from sources to depositional environments? |
Modelers |
| Are the data necessary to implement an offset program available or estimable? |
Scientists |
| Are there enough data to understand mercury loading/concentration? |
Scientists |
| Can we account for episodic events/time lags/heterogeneous geographic impacts/transboundary effects on mercury transport? |
Scientists |
2. Methylation Potential
| Concern |
Source |
| Can we model methylation potential in a single watershed with varying environmental conditions? |
Modelers |
| Will reducing methylation potential in one area reduce methyl-mercury contents in fish at that location? |
Scientists |
| Can we influence methylation factors to reduce methyl-mercury contents in fish? |
Scientists |
3. Bioavailability
| Concern |
Source |
| Which factors influence bioavailability in your watershed? |
Scientists |
| Which sources are more bioavailable? |
Scientists |
| Which depositional areas are more susceptible to bioavailable conditions? |
Scientists |
| Is it more bioavailable at this particular offset site than another? Can we reduce bioavailability at this site? Will reducing bioavailability reduce methyl-mercury contents in fish? |
Scientists |
| Can we model bioavailability? |
Modelers |
4. Trophic Transfer/Human Transfer
| Concern |
Source |
| Can we estimate which areas have higher concentrations of fishermen (who catch for subsistence)? |
U.S. Fish and Wildlife Service |
| Can we estimate the risk of fish contamination? |
EPA |
| Can we measure the risk of consumption of fish with methyl-mercury concentrations? |
Scientists |
| Can we measure the linkages between the methyl-mercury in zooplankton and sport fish? |
Scientists |
| Does reducing mercury loading, methyation potential, or bioavailability (or any other remediation options) from an area reduce methyl-mercury concentrations in fish? |
Modelers |
B. Implementation
1. Legal Concerns
| Concern |
Source |
| Is the stream reach on the Clean Water Act’s 303 (d) list? |
EPA TMDL List |
| Is the area being remediated on public land? |
Ownership Map |
| Would offset participants be protected from contingent liabilities? |
EPA |
| Would the offset project cause localized impacts or “hotspots”? |
Scientists |
| Has the point source complied with the CWA’s provisions for performing technology- based effluent limitations (TBELs) as the floor minimum? |
EPA Clean Water Act (CWA) |
| Does the proposed offset prevent noncompliance with anti-backsliding rules of the CWA? |
EPA CWA |
(for example, CWA; Resource Conservation and Recovery Act; CERCLA; Emergency Planning and Community Right to Know Act; Surface Mining and Reclamation Act; Porter Cologne Water Quality Control Act; Water Code, Section 13397-13398.9; CA Fish and Game 5650; Health and Safety Code 105705; Public Resources Code 2755-2764; Toxic Pits Clean-up Act of 1984; Historical Preservation Act)
2. Project Logistics/Administrative Concerns
| Concern |
Source |
| Does the proposed offset agree with all of the proposed guidelines governed by the regulatory community? |
RWCQB |
| Are governmental authorities and potential offset participants capable of administering an offset program? |
WWTP/RWQCB/EPA |
| Do governmental authorities have enforcement mechanisms to ensure that offsets are being implemented correctly and applicable limits are being met? |
RWCQB |
| Is the offset site accessible? (road access/steepness of slope) |
WWTP |
| Is it possible to change land use? (for example, wetlands) |
EPA |
| Is accountability for implementation of remediation measures clearly established? |
EPA/RWQCB |
3. Remediation Costs
| Concern |
Source |
| Are remediation techniques identifiable to clean up this particular site? |
Engineers |
| Are there unit-cost estimates for each remediation technique? |
Engineers |
| Is there good confidence in remediation results and cleanup for various techniques? |
Engineers |
| Is there good confidence in the predicted cost of the proposed offset project? |
Engineers |
| Are transaction costs less than cost savings from the offset? |
Research |
| Do total incremental costs (marginal) for pollution reduction differ among non-point-source and point-source sites and dischargers, [for example, wastewater-treatment plants (WWTP), mines, etc.]? |
Research |
| Can point sources estimate their direct costs for reducing a specified unit of mercury/methyl-mercury? |
WWTP |
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