Protecting Public Health and the Environment.
DEQ's water quality criteria may not always reflect the toxicity of a pollutant in a specific water body. They represent only a limited number of the natural and humanmade chemicals that exist in the environment that may pose a threat to designated or existing beneficial uses. Therefore, it may be prudent in some water bodies to develop new water quality criteria or modify existing criteria through site-specific analyses that will effectively protect designated and existing beneficial uses.
Site-specific criteria are allowed by regulation and are subject to EPA review and approval. As with all water quality criteria, site-specific criteria must be based on sound scientific principles in order to protect the designated use.
The following are acceptable conditions for developing site-specific criteria:
DEQ's procedures to derive site-specific criteria can be found in Idaho's Water Quality Standards (IDAPA 58.01.02, Section 275.01(h)).
Some site-specific criteria have been established for specific Idaho water bodies to reflect local environmental conditions.
Site-specific criteria have been established for cadmium, lead, and zinc in the South Fork Coeur d'Alene River (SFCDA) subbasin. The SFCDA site-specific criteria were developed using EPA's "resident species" approach that involved testing the toxicity of cadmium, lead, and zinc in actual site water near the headwaters of the SFCDA (upstream of pollution from mining activities) using native species that occur in the subbasin. The studies included toxicity tests with 14 species, including westslope cutthroat trout, shorthead sculpin, mayflies, stoneflies, caddisflies, other insects, and snails.
The following DEQ technical documents describe the criteria derivation for cadmium, lead, and zinc and an evaluation of whether criteria developed for cadmium, lead, and zinc using species and water from the headwater reaches of the SFCDA watershed are appropriate to apply to the lower SFCDA and tributaries.
Site-specific criteria have been established for copper and lead in the Boise River. The Boise River site-specific criteria were developed using EPA's “water-effect ratio” (WER) approach that involved comparing the relative toxicity of copper and lead in river water and in lab water that was intended to represent the typical lab waters used by EPA to develop national criteria guidance. The WER studies used standard aquatic test organisms (fathead minnows and the water flea Ceriodaphnia dubia) in side-by-side comparisons in actual site (river) water and lab water. The following document describes this project in detail.
On November 14, 2003, Idaho adopted a site-specific temperature criterion to protect fall Chinook spawning in the reach of the Snake River from Hells Canyon Dam to the Salmon River. That criterion is a maximum weekly maximum temperature of 13°C, based on EPA’s Region 10 recommendation to protect salmonid spawning, and applies from October 23 through April 15 of each year. EPA, after consultation with NOAA Fisheries, approved this criterion on July 20, 2004.
In 2011, DEQ initiated rulemaking to revise Idaho’s Water Quality Standards to modify the existing site-specific temperature criterion. The rule, which was approved by the Board of Environmental Quality and adopted by the Idaho Legislature, established a site-specific criterion of maximum weekly maximum temperature of 14.5°C from October 23rd through November 6th and a maximum weekly maximum temperature of 13°C from November 7th through April 15th.
On January 30, 2012, Simplot Corporation delivered to DEQ for the agency’s consideration a proposal for a site-specific selenium criterion and supporting technical documents. The proposal is for a fish egg/ovary criterion, with translation to wholebody tissue selenium and water selenium concentrations as well, and would apply to certain streams draining Simplot’s Smoky Canyon Mine in southeast Idaho.
DEQ is reviewing the proposal and its supporting documents. When that is done, DEQ will make a decision to either proceed with rulemaking to adopt the selenium site-specific criterion as proposed, modify the proposal and then proceed, or request further information from Simplot before proceeding. DEQ anticipates reaching this decision within a couple of months of receiving the proposal.
If DEQ proceeds with rulemaking, at least one negotiated rulemaking meeting will be held. This meeting will be announced in Idaho’s Administrative Bulletin will be open to the public. Based on the negotiations, DEQ could publish a proposed rule and take formal public comment or end the process.
The opportunities for public comment during rulemaking include the following steps:
All final water quality rules must be submitted to EPA for approval. Only with EPA approval would the site-specific criterion become be effective for purposes such as 303(d) listing decisions, TMDLs, or NPDES permitting under the Clean Water Act.
Each state step—initiation of negotiated rulemaking, proposed rule, pending rule, and final rule—is published in the Idaho Administrative Bulletin. DEQ also tracks the process on its website. Check back for further developments.
Water Quality Standards CoordinatorDon EssigDEQ State Office1410 N. HiltonBoise, ID 83706(208) email@example.com