Montana Administrative Register Notice 17-412 No. 16   08/28/2020    
Prev Next


                                          OF THE STATE OF MONTANA


In the matter of the adoption of New Rule I pertaining to natural and nonanthropogenic water quality standards









            TO: All Concerned Persons


           1. On April 30, 2020, the Board of Environmental Review (board) published MAR Notice No. 17-412, pertaining to the public hearing on the proposed adoption of the above-stated rule at page 765 of the 2020 Montana Administrative Register, Issue No. 8.


           2. The board has adopted NEW RULE I (ARM 17.30.618) exactly as proposed.


3. The board has thoroughly considered the comments received. A summary of the comments received and the board's responses are as follows:


COMMENT NO. 1:  We appreciate and thank the department for its extensive work gathering data, modeling, carrying out research, meeting with stakeholders, and drafting complicated technical documents that have led to this rulemaking.

RESPONSE:  The board and department thank you for the comment.


COMMENT NO. 2:  Since this is the first nonanthropogenic based standard rulemaking, it is important to get the rule correct so that it protects beneficial uses and provides for reasonable and effective implementation.

RESPONSE: The board agrees with the comment.


COMMENT NO. 3:  I do not understand why it is in the public interest to allow polluters to add arsenic to the Yellowstone River at above 10 µg/L even if 75-5-222(1), MCA, says it is allowable.

RESPONSE:  The board, as well as the department, must follow the requirements of 75-5-222(1), MCA.  The department has collected considerable data to establish the nonanthropogenic condition of total recoverable arsenic within the identified segments of the Yellowstone River. When formulating and adopting standards of water quality, the board must also consider the economics of waste treatment and prevention under 75-5-301(2), MCA. Requiring water that will be discharged to the river to be treated to 10 µg/L arsenic when the river's nonanthropogenic condition has been established at higher concentrations incurs an unnecessary economic burden on dischargers.  The legislature directed the board and the department to ensure that water quality standards are applied at the nonanthropogenic condition of a water body.


COMMENT NO. 4:  The most protective arsenic standards for human health and the environment for each segment of the Yellowstone River should be adopted, regardless of economic investment by MPDES permittees to meet such standards.

RESPONSE:  See response NO. 3.


COMMENT NO. 5:  We support the explicit prohibition of mixing zones and intake credits as there is no assimilative capacity for nonanthropogenic standards and we support permittees being required to meet end-of-pipe nonanthropogenic standards.

RESPONSE:  The board agrees with the comment.  See responses NO. 6 and NO. 7.


COMMENT NO. 6:  Given the unique issues that arise from naturally occurring pollutants, it would be appropriate to include a provision that allows for consideration of intake credits when implementing the standard. Recognizing that there may not be a practical way to ensure the standard and the natural condition are equal all the time, and that sometimes the standard will be more stringent than the natural condition, including a provision for intake credits provides another tool that may be used to ensure compliance with the Montana Water Quality Act.

RESPONSE:  The board disagrees with the comment. With NEW RULE I, the board is directly addressing the naturally occurring pollutant (arsenic) in the Yellowstone River by establishing new standards at concentrations greater than the current standard.  By using annual median nonanthropogenic arsenic levels in the Yellowstone River, the proposed standards already give dischargers credit for naturally occurring concentrations which are above the current standard. As a result, any need for a water quality standards-based intake credit is precluded by the nonanthropogenic standard itself. Even if the board were to adopt a water quality standards-based intake credit rule, as other states have done, such a tool could not be used to provide intake credit where nonanthropogenic standards already apply.

The board also recognizes the river's concentrations will vary from year to year. However, variability is already accounted for within the new standards. While approximately half the years will have somewhat higher arsenic concentrations than the new standards, the other half will have somewhat lower concentrations. Allowing intake credits only for the "high arsenic years" while not also requiring treatment to better than the standard during the "low arsenic years" will lead to increase in the river's arsenic concentration over the long-term.


COMMENT NO. 7:  The board should consider adding provisions to the rule that provide access to current and appropriate regulatory tools that specifically provide for consideration of dilution and mixing zones, or at a minimum ensure the rule is silent on those provisions so the more appropriate governing portions of the federal Clean Water Act and the Montana Water Quality Act may continue to govern without conflict. Including reference to mixing zones in this new rule is unnecessary and may lead to unforeseen consequences and conflicts.

RESPONSE: The board considered the request and concludes that the rule should address mixing zones as currently proposed in (3) of NEW RULE I.  Mixing zones are only appropriate when the background condition of the receiving water is below the applicable water quality standard. Here, the nonanthropogenic standards are established right at the long-term median nonanthropogenic condition of a waterbody; that is, at the central tendency of the naturally occurring pollutant. The board believes that a measure of central tendency (in this case the median nonanthropogenic concentration) is the best representation of the nonanthropogenic condition. Any anthropogenic increase in the concentration of such a waterbody would move the nonanthropogenic condition away from its central tendency and away from the nonanthropogenic condition. As a result, there is no assimilative capacity with nonanthropogenic standards and mixing zones are not appropriate.


COMMENT NO. 8:  The board should consider adding provisions to the rule that provide access to current and appropriate regulatory tools that allow implementation of the standards either as a load or as a concentration.

RESPONSE:  The board disagrees with the comment. The standards have been developed as concentrations and any MPDES permit limits will be expressed as concentrations to ensure the discharge is meeting the standard. This is consistent with the large number of concentration-based water quality standards that have been adopted by the board.


COMMENT NO. 9:  If the arsenic standard becomes artificially low during a "high arsenic concentration" year, a permittee is at risk of permit violations, enforcement actions, and perhaps a citizen suit under the federal Clean Water Act. The rule and/or technical support documents should clarify that such a situation is not a violation of the permit limits.

RESPONSE:  Permittees will be required, under NEW RULE I, to treat their discharge effluent to the nonanthropogenic standard concentration, unless a permittee's discharge will not cause or contribute to an exceedance of the standard.  Adoption of the proposed arsenic standards increases allowable concentrations to levels above the currently applicable standard of 10 µg/l, thereby lessening the burden of compliance. While variability is already accounted for within the new standards, the standards may be revised should median nonanthropogenic concentrations change significantly.


COMMENT NO. 10:  If the nonanthropogenic condition of the river trends upward over time and results in a higher standard, it should be clear in the rule or the supporting technical documents that the permit limit may be increased in accordance with the higher nonanthropogenic level without risking an anti-backsliding claim.

RESPONSE: The anti-backsliding provisions of state and federal law prohibit the renewal, reissuance, or modification of an existing permit to contain effluent limitations less stringent than those established in a previous permit, unless an exception applies. In general, revised standards do not justify the application of a less stringent effluent limitation. See 40 C.F.R. § 122.44(l). Anti-backsliding requirements are applied on a case-by-case basis through the MPDES permitting process and are outside the scope of this rulemaking.


COMMENT NO. 11:  The department should, in the proposed rule, provide a categorical exemption stating that "point source dischargers who discharge water utilized for non-contact cooling purposes only into the same segment of the river from where the water was withdrawn are exempt from the proposed water quality standards limitations."

RESPONSEThe purpose of this rule is to adopt water quality standards based upon natural and nonanthropogenic conditions and, specifically, the establishment of total recoverable arsenic standards for four segments of the Yellowstone River.  The board disagrees this is the appropriate rule for such an exemption and finds the request to be outside the scope of this rulemaking.


COMMENT NO. 12:  The board should consider removing or modifying footnote 16 of Department Circular DEQ-7. Currently, the footnote indicates no sample shall exceed the human health standard.

RESPONSE:  Thank you for your comment. However, it is outside the scope of this rulemaking.


COMMENT NO. 13:  Are there any public water systems in the segments of the Yellowstone River with proposed site-specific arsenic criteria that have data demonstrating that the river source water with arsenic of 60 µg/L can be treated to below 10 µg arsenic per liter?

RESPONSE: The comment refers to the highest anticipated instream arsenic concentration (60 µg/L arsenic) which was estimated using the department's modeling for the Yellowstone River from the Montana/Wyoming border (44.9925, -110.5172) to the mouth of Mill Creek (45.4165, -110.6548). The standard being proposed for the segment is 28 µg/L. Currently, there are no public water supply systems on that segment of the river; the town of Gardiner, which is located on the segment, stopped using the river as a water source over ten years ago and now only uses water sourced from wells. The other public water supply on a segment with proposed new arsenic standards is in the city of Laurel, which draws water from the Yellowstone River in the segment from the mouth of the Stillwater River (45.6399, -109.2829) to the mouth of the Clarks Fork of the Yellowstone River (45.6510, -108.7145). The proposed arsenic standard in this segment is 13 µg/L. The department examined the arsenic concentrations in Laurel's finished drinking water and the corresponding concentrations in the river when the water was withdrawn, using methods identical to those used for Billings and described in Section 2.1 of its 2020 technical document Addendum to Derivation of the Nonanthropogenic Standards for Segments of the Upper and Middle Yellowstone River. Over the time period data was available (2009-2018), the department found that the Yellowstone River's arsenic ranged from 10 to 19 µg/L, and Laurel's drinking water complied with the arsenic standard (10 µg/L) on all but one occasion—when it measured 11 µg/L. Importantly, the exceedance did not occur when the river's arsenic was particularly high (it was 13 µg/L at the time) and is unrelated to the time periods when the river's arsenic ran highest. These findings indicate that the Laurel public water supply—the only system actively drawing water from the Yellowstone River in the segments addressed by NEW RULE I—can treat arsenic to ≤ 10 µg arsenic per liter when the river's arsenic concentration is as high as 19 µg/L.


COMMENT NO. 14:  NEW RULE I states that the site-specific arsenic criteria are "Water quality standards for human health." Please provide information to explain how the criteria will protect human health from exposure to arsenic through fish consumption.

RESPONSE: The United States Environmental Protection Agency (EPA) provides two equations to calculate an arsenic concentration standard protective of human health; one equation assumes the waterbody is used for drinking and that a drinking water treatment process will not further lower the contaminant concentration, and also that fish are eaten from the same waterbody. The other equation assumes that the only route of exposure is via consumption of fish from the waterbody. The latter equation (referred to as "organism-only") can be used to determine a protective arsenic concentration for fish consumption, and that result can then be compared to the nonanthropogenic arsenic standards being proposed for the Yellowstone River. Key assumptions adopted in Department Circular DEQ-7 (June 2019 version) are as follows:  an average human body weight of 80 kg, fish consumption of 0.022 kg/day, and an arsenic bioconcentration factor of 44. Using these assumptions, the organism-only equation indicates 47 µg arsenic per liter would be protective for fish consumption (at Montana's arsenic carcinogen risk factor of 10-3, per 75-5-301(2)(a), MCA). The highest nonanthropogenic arsenic standard being proposed on the Yellowstone River is 28 µg arsenic per liter, lower than 47 µg arsenic per liter. The board notes that river water is used for drinking within the affected Yellowstone River segments (Laurel has a public water supply), but arsenic in the river's water is first treated to ≤ 10 µg/L before distribution. Thus, the board concludes the proposed Yellowstone River nonanthropogenic standards will protect human health from exposure to arsenic through fish consumption.


COMMENT NO. 15:  If an anthropogenic source introduces water with a concentration at or below 28 µg/L, the concentration in the river does not increase, but the total mass of arsenic in the river does increase.

RESPONSE: The board agrees with the comment. Any additional mass of arsenic added to the river from a water source which did not originate from the river itself will increase the river's total load.


COMMENT NO. 16:  Under the proposed rule, simple water evaporation (of Yellowstone River water) due to ambient temperatures would increase the non-impacted arsenic load to an arsenic concentration higher than what was diverted from the river. The user of the water would then be forced to treat the water to remove nonanthropogenic arsenic before discharge.

RESPONSE:  In the scenario provided, the user is not simply using and then returning Yellowstone River water in its original state; the user's actions have resulted in the return water having a higher concentration than when it was initially diverted. When returned to the river, the higher arsenic concentration of the returned water will increase the river's arsenic concentration. The standards are written to concentration; therefore, the end result of the commenter's scenario is no different than if the user had mixed water with elevated anthropogenic arsenic from some other source with the withdrawn Yellowstone River water, and then returned all the water to the river. Either way, the river's concentration has increased due to anthropogenic actions.  Therefore, treatment to the non-anthropogenic standard is appropriate.


COMMENT NO. 17:  The department should allow an option to implement procedures/criteria utilizing a 12-month rolling average, calculated monthly, in order to comply with the nonanthropogenic condition present in the waterbody at all times of the year.

RESPONSE:  The board disagrees with the comment. The board understands that the request represents a potential way for a permittee to remain in compliance with a nonanthropogenic standard by accounting for near-term natural variability which temporarily increases the river's concentration above the nonanthropogenic standard. However, the department analyzed this approach using its modeled arsenic data and permittee arsenic discharge data, and found that it does not resolve the compliance concern at hand. For arsenic in the Yellowstone River, the department found that a rolling 12-month median is basically the same as other retrospective data compilations; it uses historic data to predict the present.  The department found that the median or average arsenic concentration of the preceding 12 months may have little or no predictive relationship with the current month. And since permit compliance is based on meeting the current month's limits, if the current month happens to be high (i.e., is naturally elevated above the nonanthropogenic standard) comparing the current month to the previous 12-month rolling value may still indicate the permittee's discharge is above the standard.


COMMENT NO. 18:  The language in the reason section of the MAR Notice No. 17-412 sets the tone for future rulemaking and should clarify what reasons apply to the Yellowstone River for arsenic but may not apply elsewhere or for other parameters. Therefore, revisions should be made to the MAR notice. The last sentence on page 766, which carried to page 767, should be revised for the final notice, as follows:  "The proposed nonanthropogenic arsenic standards for the Yellowstone River are protective of human health, which is the beneficial use in the Yellowstone River that is most sensitive to arsenic levels."

RESPONSE:  The board disagrees with the comment. Future rulemakings must contain reasonable necessity statements supporting related rules. Here, the proposed nonanthropogenic arsenic standards for the Yellowstone River are protective of human health when the river's water is conventionally treated for drinking water purposes. The human health drinking water use in the Yellowstone River is the most sensitive to nonanthropogenic arsenic levels.


COMMENT NO. 19:   Revisions should be made to MAR Notice No. 17-412. The first full sentence on page 767 should be revised for the final notice, as follows:  "Because the proposed standards reflect the nonanthropogenic condition of the Yellowstone River, they protect beneficial uses, comply with Water Quality Act, and enable regulation of point source discharges."

RESPONSE:  The board disagrees any revisions to the MAR notice are necessary.  The proposed standards do not enable regulation of point source dischargers; such authority is provided by the Water Quality Act, Title 75, chapter 5, MCA, and the related permitting rules.  See also response NO. 18.


COMMENT NO. 20:  Section (3) of the rule, as well as the last paragraph in the reason section of MAR Notice No. 17-412, precludes the possibility of assimilative capacity for the applicable nonanthropogenic or natural standards, and denies mixing zones. Section (3) of the proposed rule should be removed.

RESPONSE: The board disagrees that (3) of the proposed rule should be removed. See also response NO. 7.


COMMENT NO. 21:  If (3) is not removed, it should be modified to have appropriate sideboards placed on it. More appropriate language would be as follows:  "In accordance with 40 CFR 122.44(d)(1)(iii) and Title 17, chapter 30, subchapter 5 of these regulations, dilution and mixing zones may be considered for discharges to the waterbodies and for the parameters listed in this rule; however, for toxic and carcinogenic parameters, dilution and mixing zones may only be considered for discharges with an average flow of less than 1 percent of the 7Q10 low flow of the waterbody and an annual load of less than 1 percent of the annual average of the load of the parameter."

RESPONSE: The board disagrees with the comment. See also responses NO. 7 and NO. 20.


COMMENT NO. 22:  Including the term "assimilative capacity" in (3) of the rule injects a new term into the rules, is unnecessary, and may lead to unforeseen consequences. Based on current regulatory and statutory language, the department already has the ability to determine when loading (or assimilative) capacity exists, which makes (3) of the rule unnecessary and confusing.

RESPONSE:  The board disagrees with the comment. In (3) of the proposed rule, the term "assimilative capacity" provides context as to why mixing zones are not allowed for nonanthropogenic standards. Assimilative capacity is a fundamental requirement for the implementation of water quality standards and any related mixing zone or dilution consideration.  See also response NO. 7.


COMMENT NO. 23:  Discussion of permitting should be deleted from the technical support document, specifically Section 4.2 of the document Derivation of the Nonanthropogenic Arsenic Standards for Segments of the Upper and Middle Yellowstone River.

RESPONSE:  The board disagrees with the comment. The guidance document was developed cooperatively between the department's Standards & Modeling and Permitting sections, and released as final in late 2019. As a final technical document, it provides the department's non-binding recommendations for how to implement nonanthropogenic standards.


COMMENT NO. 24:  We would like to have the inclusion of intake credits to prevent the need for further investment and operation costs where in the end we are really not going to have any kind of measurable impact on the river.

RESPONSE: The board disagrees with the comment.  Please see response NO. 6.


COMMENT NO. 25:  To enable an intake credit provision, the following text should be added either to proposed NEW RULE I or to the supporting technical documents:  "The standards provided herein may be implemented as annual average standards, either in terms of load or concentration; intake credits may be considered for permittees that take surface water directly from, and/or groundwater that originates or is influenced by, the same waterbody to which the effluent discharges."

RESPONSE:  The board disagrees with the comment. Please see also responses NO. 6 and NO. 8. The board is aware that interactions between surface waterbodies and adjacent groundwater occur, however they are not the same waterbodies and it is common for them to have drastically different water quality.  The nonanthropogenic standards in NEW RULE I apply to the Yellowstone River and groundwater standards are outside the scope of this rulemaking.



Reviewed by:                                                BOARD OF ENVIRONMENTAL REVIEW



/s/ Edward Hayes                              BY:  /s/ Christine Deveny                                    

EDWARD HAYES                                     CHRISTINE DEVENY

Rule Reviewer                                           Chair


            Certified to the Secretary of State August 18, 2020.

Home  |   Search  |   About Us  |   Contact Us  |   Help  |   Disclaimer  |   Privacy & Security