I. Statewide Rule 57 Water Quality Values

General Information

The following are instructions for Interpreting the Rule 57 Water Quality Values Spreadsheet:

Using Rule 57, the following values are determined:

• Human Noncancer Value (HNV): “drink” and “non-drink”
• Human Cancer Value (HCV): “drink” and “non-drink”
• Wildlife Value (WV): (calculated only for Bioaccumulative Chemicals of Concern)
• Final Chronic Value (FCV)
• Aquatic Maximum Value (AMV)
• Final Acute Value (FAV)

The above terms and their uses are defined in the Part 4 Rules.  The use of these values to assess point source discharges and venting groundwater is described in the Part 8 Rules, Water Quality-Based Effluent Limits for Toxic Substances of the NREPA.  Within the Rule 57 Water Quality Values spreadsheet, the identification of a value as “drink” or “non-drink” refers to whether or not a surface water body is designated and protected as a source for a public drinking water supply (See Rule 100 [R 323.1100] – Designated Uses, of the Part 4 Rules).

The following are links to statewide and site-specific Rule 57 water quality values that have been derived for the state of Michigan.  Due to the complexity of the equation used to derive aquatic life values for ammonia, a link is provided to tables showing what the ammonia aquatic life values would be at different temperatures and pHs.

Each chemical is identified by a Chemical Abstract Service number (CAS#) and each Rule 57 water quality value has a Tier status associated with it (Tier 1 or Tier 2) and the year the value was verified.  Tier 1 values are calculated using an optimal set of toxicological data while Tier 2 values are calculated using a lesser amount of data (see Rule 57 for further description of tier designation).  The verification date refers to the year the water quality value was approved for entry into the spreadsheet.

If a substance is not listed in the spreadsheet or if a value is identified with an “ID” (insufficient data) or “NLS” (no literature search), then final values have not been derived. 

Ammonia

The toxicity of ammonia to aquatic life is pH- and temperature-dependent; therefore, the Rule 57 aquatic life values are equation-based. Equations for calculating the aquatic life values for total ammonia are provided below the Rule 57 table. Due to the complexity of these equations, the following tables are provided to facilitate the determination of aquatic life values at various pHs (6.5-9) and temperatures (0-30°C).

Download Ammonia Aquatic Life Value Tables

II. Site-specific Rule 57 Water Quality Values

R 323.1057(2)(r) of the Part 4 Rules gives procedures for deriving site-specific aquatic life values that reflect local environmental conditions.  The following documents contain the site-specific aquatic life water quality values that have been derived for copper for select streams in the Upper Peninsula of Michigan, and supplemental information used in deriving criteria.

Site-Specific Aquatic Life Values for Total Copper for Select Water Bodies in the Upper Peninsula of Michigan

Development of Site-Specific Aquatic Life Values for Total Copper for Water Bodies in the Upper Peninsula Waters - Supplemental Information

Development of a Copper Criteria Adjustment Procedure for Michigan’s Upper Peninsula Waters - Supplemental Information

III. Procedure for Updating Statewide Rule 57 Water Quality Values

 In fiscal year (FY) 2024, a revised procedure for prioritizing routine updates to published Rule 57 values was implemented. The key principle in the procedure is to prioritize chemicals with the highest potential human health or aquatic life impacts (i.e., highest hazard) as well as chemicals with high frequency of occurrence and/or relevance within EGLE’s water quality-based permitting processes. Four criteria associated with the current Rule 57 values are utilized in determining priority:

1. Chemical hazard classification using the Globally Harmonized System framework.
2. EGLE, Water Resources Division (WRD), priorities.
3. Last Review Date (LRD), which is the year the chemical was last reviewed.
4. Rule 57 assessment tier, which reflects available chemical data when last reviewed.

Separate prioritization lists are developed for Rule 57 human health values and aquatic life values.

It is the intent to use this prioritization procedure to determine which Rule 57 chemicals are to be reviewed in each fiscal year. The review process consists of identifying any new scientific literature for the selected Rule 57 chemical and determining if such new data supports a revision to the currently published Rule 57 values. If prior Rule 57 values are still acceptable, the LRD for the target chemical will be updated to reflect that year that the review was performed.

An exception to this prioritization procedure may occur if new data for a specific chemical becomes available that suggests the current Rule 57 values represent a significant risk to either aquatic life or human health, then such chemical may be subject to an updated review ahead of its overall prioritization score.

For development of novel Rule 57 values, selected chemicals are based on review of current scientific literature as well as EGLE, WRD, priorities.

The Rule 57 Water Quality Values Spreadsheet will be updated, as necessary, to include new or revised values.

IV. What’s New in FY 2024?

As an additional process improvement beyond the prioritization procedure described above, the “verification year” column, in the previous published online Rule 57 table (dated October 12, 2023) has been replaced with two separate columns: (1) Current Value Date (CVD); and (2) Last Review Date (LRD). The CVD represents the year when the current listed Rule 57 values were established while the LRD represents the year when current Rule 57 values were last reviewed. This adds clarity to the Rule 57 table as prior “verification year” date was inconsistent as to the date Rule 57 values were established and date of last review. An internal review of all electronic and paper documentation was used to derive the CVD and LRD dates.

An update to Rule 57 human health values for 2,4-dichlorophenoxyacetic acid (CAS #95-75-7), commonly known as 2,4-D, was completed. The revised human health non-cancer Rule 57 values are 430 micrograms per liter (µg/L) (drinking water) and 4700 µg/L (non-drinking water). The previous Rule 57 human health values were 240 µg/L (drinking water) and 1900 µg/L (non-drinking water).

New Rule 57 human health values were developed for both parathion (CAS #56-38-2) and methyl parathion (CAS #298-00-0). From review of the literature for parathion, it was determined that it was appropriate to assign human health values for both parathion and methyl parathion. For parathion, Rule 57 human health non-cancer values were 17 µg/L (drinking water) and 54 µg/L (non-drinking water). For methyl parathion, Rule 57 human health non-cancer values were 5 µg/L (drinking water) and 88 µg/L (non-drinking water).

An updated literature search and review was performed for diquat (CAS #2764-72-9). Following review of any new literature and published risk assessments, it was determined that no changes were necessary to the current published Rule 57 human health non-cancer values for diquat.