Copper Aquatic Life Criteria Monitoring and Assessment Issues
Supplementary Training Materials
- 1.1 What does the BLM mean for state water quality monitoring efforts?
Depending on how a state or tribe chooses to implement the BLM-based copper criteria, the impacts to state water quality monitoring programs are likely to vary. For example, if a state chooses a site-specific implementation approach and retains the existing hardness-based criteria (adopted into state standards as a hardness equation) and uses the BLM on a targeted basis, there should be minimal changes expected to that state’s existing water quality monitoring efforts. States and tribes may choose to work with direct dischargers to collect monitoring data for the BLM. If, however, a state chooses to adopt the BLM as the statewide standard, expanded water quality monitoring efforts probably would be necessary to gather data for the 10 input parameters used by the BLM.
- 1.2 How should states and tribes direct future monitoring efforts?
To the extent feasible, EPA recommends that states and tribes incorporate BLM input parameters into their statewide monitoring efforts to ensure that data are available should the State or tribe choose to adopt the BLM. The additional monitoring data also would be useful if and when the BLM is developed for other metals, such as zinc and silver.
- 1.3 How does one use ambient water quality monitoring data to assess BLM-based copper criteria?
Assessing whether receiving waters are meeting BLM-based copper criteria would be similar to assessing attainment using the previous hardness-based criteria. If a state or tribe previously adopted a site-specific numeric criteria value using the BLM, then assessment would involve measuring copper at the site and comparing it to the previously determined value. If a state or tribe uses the BLM as the basis for the criteria and did not establish a site-specific numeric values, the state/tribe would collect monitoring data for the 10 input parameters and copper at each site, run the BLM using the monitoring data, and then compare the BLM-derived copper criteria with the measured copper value at each site. Assessing copper criteria using the BLM would not alone substitute for other integrative measures of water quality standards, such as biological assessments and ambient toxicity tests.
- 1.4 How will the updated criteria affect 303(d) listings and TMDLs for waters currently listed as impaired for copper?
The impact of implementing the BLM on 303(d) listings and TMDLs will depend on whether a state implements the criterion on a site-specific basis or a statewide basis, as discussed in "Training materials on Copper BLM: Implementation." In general, EPA Training materials on the Biotic Ligand Model for copper expects that fewer water bodies will be listed as impaired due to copper because the current hardness-based criteria are potentially over-protective for many waters, particularly in point-source effluent dominated waters and those with high DOC levels. While some water bodies with high DOC levels may be de-listed (high DOC levels decrease copper toxicity), some water bodies, such as those with low pH and low DOC, may be added because the hardness-based criteria would be potentially under-protective of these waters. An example of a low pH, low DOC water body is an area experiencing acid mine drainage. EPA is currently conducting an analysis to determine the impacts of the BLM on water bodies currently listed as impaired for copper and intends to provide further information as it becomes available.
EPA expects that a State or tribe would continue to list water bodies currently listed as impaired due to copper until those waters can be assessed against the new criterion after adoption by the State (or tribe) and approval by EPA. For situations in which a TMDL has been adopted and the criterion subsequently revised, EPA intends to develop a clarification memo regarding adjusting, revising, and withdrawing a TMDL, which should address this scenario.
For further information on identifying and listing impaired waters, see "Information Concerning 2008 Clean Water Act Sections 303(d), 305(b), and 314 Integrated Reporting and Listing Decisions," October 12, 2006 and "Guidance for 2006 Assessment, Listing, and Reporting Requirements Pursuant to Sections 303(d), 305(b) and 314 of the Clean Water Act," July 29, 2005.