Document ID: EPA-HQ-OW-2017-0010-0001
Agency: epa
Document Type: Proposed Rule
Title: Water Quality Standards for State of Missouri's Lakes and Reservoirs
Posted Date: 2017-12-27T05:00Z

[Federal Register Volume 82, Number 247 (Wednesday, December 27, 2017)]
[Proposed Rules]
[Pages 61213-61229]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-27621]

-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 131

[EPA-HQ-OW-2017-0010; FRL-9972-46-OW]
RIN 2040-AF69

Water Quality Standards for the State of Missouri's Lakes and 
Reservoirs

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

-----------------------------------------------------------------------

SUMMARY: The Environmental Protection Agency (EPA or Agency) proposes 
to establish federal nutrient criteria to protect designated uses for 
the State of Missouri's lakes and reservoirs. On August 16, 2011, EPA 
disapproved most of the numeric criteria for total nitrogen, total 
phosphorus, and chlorophyll a that the State submitted to EPA in 2009. 
EPA acknowledged the importance of Missouri's proactive efforts to 
address nutrient pollution by adopting numeric nutrient criteria. 
However, EPA concluded that the Missouri Department of Natural 
Resources (MDNR) had failed to demonstrate the criteria would protect 
the State's designated uses and were not based on a sound scientific 
rationale. The Clean Water Act (CWA) directs EPA to promptly propose 
water quality standards (WQS) that meet CWA requirements if a state 
does not adopt WQS addressing EPA's disapproval. On February 24, 2016, 
the Missouri Coalition for the Environment (MCE) filed a lawsuit 
alleging that EPA failed to satisfy its statutory obligation to act 
``promptly.'' On December 1, 2016, EPA entered into a consent decree 
with MCE committing to sign a notice of proposed rulemaking by December 
15, 2017 to address EPA's 2011 disapproval, unless the State submits 
and EPA approves criteria that address the disapproval on or before 
December 15, 2017. As of the date of this proposed rule, Missouri has 
not submitted new or revised standards to address EPA's 2011 
disapproval and EPA has not approved such water quality standards. 
Therefore, under the terms of the consent decree, EPA is signing a 
notice of proposed rulemaking that proposes new water quality standards 
addressing EPA's August 16, 2011 disapproval. In this proposal, EPA 
seeks comment on two primary alternatives. Under the first alternative, 
EPA proposes nutrient protection values and eutrophication impact 
factors in a combined criterion approach. Under the second alternative, 
EPA proposes a similar combined criterion approach that would mirror 
the State of Missouri's October 2017 proposal for lake nutrient water 
quality standards. EPA will not proceed with final rulemaking (or will 
withdraw its final rule, if applicable) to address its 2011 disapproval 
if Missouri adopts and submits criteria to address EPA's 2011 
disapproval and EPA approves them as meeting CWA requirements.

DATES: Comments must be received on or before February 26, 2018.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-OW-
2017-0010, at http://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from regulations.gov. EPA may publish any comment 
received to its public docket. Do not submit electronically any 
information you consider to be Confidential Business Information (CBI) 
or other information whose disclosure is restricted by statute. 
Multimedia submissions (audio, video, etc.) must be accompanied by a 
written comment. The written comment is considered the official comment 
and should include discussion of all points you wish to make. EPA will 
generally not consider comments or comment contents located outside of 
the primary submission (i.e. on the web, cloud, or other file sharing 
system). For additional submission methods, the full EPA public comment 
policy, information about CBI or multimedia submissions, and general 
guidance on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
    EPA is offering two online public hearings so that interested 
parties may provide verbal comments on this proposed rule. The first 
public hearing

[[Page 61214]]

will be on February 7, 2018. The second public hearing will be on 
February 8, 2018. For more details on the public hearings and a link to 
register, please visit https://www.epa.gov/wqs-tech/proposed-nutrient-criteria-missouri-lakes-and-reservoirs.

FOR FURTHER INFORMATION CONTACT: Mario Sengco, Standards and Health 
Protection Division, Office of Water, Mailcode: 4305T, Environmental 
Protection Agency, 1200 Pennsylvania Avenue NW, Washington, DC 20460; 
telephone number: 202-566-2676; email address: [email protected].

SUPPLEMENTARY INFORMATION:

Table of Contents

I. General Information
    A. Does this action apply to me?
    B. What action is EPA taking?
II. Background
    A. Nutrient Pollution
    B. Statutory and Regulatory Background
    C. Deriving and Expressing Numeric Nutrient Criteria
    D. Missouri's 2009 Nutrient Criteria Submission and EPA's Clean 
Water Act Section 303(c) Action
    E. Missouri Coalition for the Environment (MCE) Lawsuit and 
Consent Decree
    F. Missouri's 2017 Proposed Nutrient WQS
III. Proposed Nutrient Combined Criterion for Lakes and Reservoirs 
in Missouri
    A. Proposed Combined Criterion Approaches
    B. Proposed Combined Criterion Alternative 1
    C. Derivation of Nutrient Protection Values for Alternative 1
    D. Proposed Combined Criterion Alternative 2
    E. Additional Alternative Approaches Considered
    F. Applicability of Combined Criterion When Final
IV. Tributary Arms
V. Endangered Species Act
VI. Under what conditions will federal standards be either not 
finalized or withdrawn?
VII. WQS Regulatory Approaches and Implementation Mechanisms
    A. Designating Uses
    B. Site-Specific Criteria
    C. WQS Variances
    D. NPDES Permit Compliance Schedules
VIII. Economic Analysis
IX. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and 
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Executive Order 13771: Reducing Regulation and Controlling 
Regulatory Costs
    C. Paperwork Reduction Act
    D. Regulatory Flexibility Act
    E. Unfunded Mandates Reform Act
    F. Executive Order 13132 (Federalism)
    G. Executive Order 13175 (Consultation and Coordination With 
Indian Tribal Governments)
    H. Executive Order 13045 (Protection of Children From 
Environmental Health and Safety Risk)
    I. Executive Order 13211 (Actions That Significantly Affect 
Energy Supply, Distribution, or Use)
    J. National Technology Transfer Advancement Act of 1995
    K. Executive Order 12898 (Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations)

I. General Information

A. Does this action apply to me?

    Citizens concerned with water quality in the State of Missouri may 
be interested in this proposed rulemaking. Entities discharging 
nitrogen or phosphorus to lakes and reservoirs, or to flowing waters 
emptying into lakes or reservoirs, could be affected directly or 
indirectly by this rulemaking because WQS are used in determining 
National Pollutant Discharge Elimination System (NPDES) permit effluent 
limits. Stakeholders that rely on lakes and reservoirs for recreation 
or as a source of drinking water likewise may be interested in the 
proposed criteria. Table 1 lists categories that ultimately may be 
affected by this proposal.

      Table 1--Categories Potentially Affected by Proposed Criteria
------------------------------------------------------------------------
           Category            Examples of potentially affected entities
------------------------------------------------------------------------
Industry.....................  Factories discharging pollutants to lakes/
                                reservoirs or flowing waters emptying
                                into downstream lakes/reservoirs in
                                Missouri.
Municipalities...............  Publicly-owned treatment works
                                discharging pollutants to lakes/
                                reservoirs or flowing waters emptying
                                into downstream lakes/reservoirs in
                                Missouri.
Stormwater Management          Entities responsible for managing
 Districts.                     stormwater runoff in Missouri.
------------------------------------------------------------------------

    This table is not intended to be exhaustive; rather, it provides a 
guide for entities that may be affected directly or indirectly by this 
action. Nonpoint source contributors and other entities not listed in 
the table also could be affected indirectly. Any party or entity that 
conducts activities within the watersheds affected by this rule, or 
that relies on, depends upon, influences, or contributes to the water 
quality of the lakes, reservoirs and flowing waters of Missouri, also 
may be affected by this rule. To determine whether your facility or 
activities may be affected by this action, you should carefully examine 
this proposed rule. If you have questions regarding the applicability 
of this action to a particular entity, consult the person listed in the 
preceding FOR FURTHER INFORMATION CONTACT section.

B. What action is EPA taking?

    The EPA is proposing two alternatives to establish federal nutrient 
criteria to protect designated uses for the State of Missouri's lakes 
and reservoirs. Under the first alternative, EPA proposes nutrient 
protection values (total nitrogen, total phosphorus, chlorophyll a) and 
eutrophication impact factors in a combined criterion approach. Under 
the second alternative, EPA proposes a combined criterion approach that 
would mirror the State of Missouri's October 2017 proposal for lake 
nutrient water quality standards. This action fulfills EPA's obligation 
under its consent decree entered on December 1, 2016 to prepare and 
publish proposed regulations for nutrient criteria to address the 
Agency's August 16, 2011, disapproval of the State's nutrient criteria 
by December 15, 2017.

II. Background

A. Nutrient Pollution

1. What is nutrient (i.e., nitrogen and phosphorus) pollution?
    Excess loading of nitrogen and phosphorus compounds \1\ is one of 
the most prevalent causes of water quality impairment in the United 
States. Nitrogen and phosphorus pollution problems have been recognized 
for some time in the U.S. For example, a 1969

[[Page 61215]]

report by the National Academy of Sciences \2\ noted ``[t]he pollution 
problem is critical because of increased population, industrial growth, 
intensification of agricultural production, river-basin development, 
recreational use of waters, and domestic and industrial exploitation of 
shore properties. Accelerated eutrophication causes changes in plant 
and animal life--changes that often interfere with use of water, 
detract from natural beauty, and reduce property values.'' Inputs of 
nitrogen and phosphorus lead to over-enrichment in many of the Nation's 
waters and create a widespread, persistent, and growing problem. 
Nitrogen and phosphorus pollution in fresh water systems can 
significantly impact aquatic life and long-term ecosystem health, 
diversity, and balance. More specifically, high nitrogen and phosphorus 
loadings result in harmful algal blooms (HABs), reduced spawning 
grounds and nursery habitats, fish kills, and oxygen-starved hypoxic or 
``dead'' zones. Public health concerns related to nitrogen and 
phosphorus pollution include impaired surface and groundwater drinking 
water sources from high levels of nitrate-nitrogen, formation of 
nitrogenous disinfection byproducts in drinking water, and increased 
exposure to toxic microbes such as cyanobacteria.3 4
---------------------------------------------------------------------------

    \1\ To be used by living organisms, nitrogen gas must be fixed 
into its reactive forms; for plants, this generally includes either 
nitrate or ammonia (Boyd, C.E. 1979. Water Quality in Warmwater Fish 
Ponds. Alabama Agricultural Experiment Station, Auburn, AL). 
Eutrophication is defined as the natural or artificial addition of 
nitrogen/phosphorus to bodies of water and to the effects of added 
nitrogen/phosphorus (National Academy of Sciences (U.S). 1969. 
Eutrophication: Causes, Consequences, Correctives. National Academy 
of Sciences, Washington, DC).
    \2\ National Academy of Sciences (U.S). 1969. Eutrophication: 
Causes, Consequences, Correctives. National Academy of Sciences, 
Washington, DC.
    \3\ Villanueva, C.M. et al., 2006. Bladder cancer and exposure 
to water disinfection by-products through ingestion, bathing, 
showering, and swimming in pools. American Journal of Epidemiology 
165(2):148-156.
    \4\ USEPA. Environments and Contaminants: Drinking water 
contaminants U.S. Environmental Protection Agency, Office of 
Research and Development. Accessed December 2017. https://www.epa.gov/sites/production/files/2015-10/documents/ace3_drinking_water.pdf.
---------------------------------------------------------------------------

    Elevated nitrogen and phosphorus levels can occur locally in a 
stream or groundwater aquifer, or can accumulate much further 
downstream leading to degraded lakes, reservoirs, and estuaries and 
material impacts on fish and other aquatic life.5 6 Excess 
nitrogen and phosphorus in water bodies come from many sources, which 
can be grouped into five major categories: (1) Urban stormwater 
runoff--sources associated with urban land use and development, (2) 
municipal and industrial waste water discharges, (3) row crop 
agriculture, (4) livestock production, and (5) atmospheric deposition 
from the production of nitrogen oxides in electric power generation and 
internal combustion engines.
---------------------------------------------------------------------------

    \5\ National Research Council. 2000. Clean Coastal Waters: 
Understanding and Reducing the Effects of Nutrient Pollution. 
National Academies Press, Washington, DC.
    Howarth, R.W., A. Sharpley & D. Walker. 2002. Sources of 
nutrient pollution to coastal waters in the United States: 
Implications for achieving coastal water quality goals. Estuaries 
25(4b):656-676.
    Smith, V.H. 2003. Eutrophication of freshwater and coastal 
marine ecosystems. Environmental Science and Pollution Research 
10(2):126-139.
    Dodds, W.K., W.W. Bouska, J.L. Eitzmann, T.J. Pilger, K.L. 
Pitts, A.J. Riley, J.T. Schloesser & D.J. Thornbrugh. 2009. 
Eutrophication of U.S. freshwaters: Analysis of potential economic 
damages. Environmental Science and Technology 43(1):12-19.
    \6\ State-EPA Nutrient Innovations Task Group. 2009. An Urgent 
Call to Action: Report of the State-EPA Nutrient Innovations Task 
Group.
---------------------------------------------------------------------------

2. Adverse Impacts of Nitrogen and Phosphorus Pollution on Aquatic 
Life, Human Health, and the Economy
    The causal pathways that lead from human activities to excess 
nutrients to impacts on designated uses in lakes and reservoirs are 
well established in the scientific literature (e.g., Vollenweider, 
1968; NAS, 1969; Schindler et al., 1973; Schindler, 1974; Vollenweider, 
1976; Carlson, 1977; Paerl, 1988; Elser et al., 1990; Smith et al., 
1999; Downing et al., 2001; Smith et al., 2006; Elser et al., 2007).\7\ 
When excessive nitrogen and phosphorus loads alter a waterbody's 
complement of algal and plant species, the corresponding changes in 
habitat and available food resources can induce cascading effects on 
the entire food web. Algal blooms block sunlight that submerged plants 
need to grow, leading to a decline in the availability of submerged 
aquatic vegetation and a reduction in habitat for juvenile fish and 
some other aquatic organisms. Algal blooms can also increase turbidity 
and impair the ability of sight-feeding fish and other aquatic life to 
find food.\8\ Large concentrations of algae can also damage or clog the 
gills of fish and certain invertebrates.\9\ Excessive algal blooms can 
lead to shifts in a waterbody's production and consumption of dissolved 
oxygen (DO) resulting in reduced DO levels that are sufficiently low to 
harm or kill important recreational species such as walleye, striped 
bass, and black bass.
---------------------------------------------------------------------------

    \7\ Vollenweider, R.A. 1968. Scientific Fundamentals of the 
Eutrophication of Lakes and Flowing Waters, With Particular 
Reference to Nitrogen and Phosphorus as Factors in Eutrophication 
(Tech Rep DAS/CS/68.27, Organisation for Economic Co-operation and 
Development, Paris. National Academy of Science. 1969. 
Eutrophication: Causes, Consequences, Correctives. National Academy 
of Science, Washington, DC.
    Schindler D.W., H. Kling, R.V. Schmidt, J. Prokopowich, V.E. 
Frost, R. A. Reid & M. Capel. 1973. Eutrophication of Lake 227 by 
addition of phosphate and nitrate: The second, third, and fourth 
years of enrichment 1970, 1971, and 1972. Journal of the Fishery 
Research Board of Canada 30:1415-1440.
    Schindler D.W. 1974. Eutrophication and recovery in experimental 
lakes: Implications for lake management. Science 184:897-899.
    Vollenweider, R.A. 1976. Advances in Defining Critical Loading 
Levels for Phosphorus in Lake Eutrophication. Memorie dell'Istituto 
Italiano di Idrobiologia 33:53-83.
    Carlson R.E. 1977. A trophic state index for lakes. Limnology 
and Oceanography 22:361-369.
    Paerl, H.W. 1988. Nuisance phytoplankton blooms in coastal, 
estuarine, and inland waters. Limnology and Oceanography 33:823-847.
    Elser, J.J., E.R. Marzolf & C.R. Goldman. 1990. Phosphorus and 
nitrogen limitation of phytoplankton growth in the freshwaters of 
North America: A review and critique of experimental enrichments. 
Canadian Journal of Fisheries and Aquatic Science 47:1468-1477.
    Smith, V.H., G.D. Tilman & J.C. Nekola. 1999. Eutrophication: 
Impacts of excess nutrient inputs on freshwater, marine, and 
terrestrial ecosystems. Environmental Pollution 100:179-196.
    Downing, J. A., S. B. Watson & E. McCauley. 2001. Predicting 
cyanobacteria dominance in lakes. Canadian Journal of Fisheries and 
Aquatic Sciences 58:1905-1908.
    Smith, V.H., S.B. Joye & R.W. Howarth. 2006. Eutrophication of 
freshwater and marine ecosystems. Limnology and Oceanography 51:351-
355.
    Elser, J.J., M.E.S. Bracken, E.E. Cleland, D.S. Gruner, W.S. 
Harpole, H. Hillebrand, J.T. Ngai, E.W. Seabloom, J.B. Shurin & J.E. 
Smith. 2007. Global analysis of nitrogen and phosphorus limitation 
of primary production in freshwater, marine, and terrestrial 
ecosystems. Ecology Letters 10:1135-1142.
    \8\ Hauxwell, J., C. Jacoby, T. Frazer, and J. Stevely. 2001. 
Nutrients and Florida's Coastal Waters. Florida Sea Grant Report No. 
SGEB-55. Florida Sea Grant College Program, University of Florida, 
Gainesville, FL.
    \9\ NOAA. 2017. Ocean Facts: Are All Algal Blooms Harmful? 
National Oceanic and Atmospheric Administration, National Ocean 
Service. <https://oceanservice.noaa.gov/facts/habharm.html>. 
Accessed December 2017.
---------------------------------------------------------------------------

    Excessive algal growth also contributes to increased oxygen 
consumption associated with decomposition (e.g., large quantities of 
senescing and decaying algal cells), in many instances reducing oxygen 
to levels below that needed for aquatic life to survive and 
flourish.10 11 Mobile species, such as adult fish, can 
sometimes survive by moving to areas with more oxygen. However, 
migration to avoid hypoxia depends on species mobility, availability of 
suitable habitat (i.e., refugia), and adequate environmental cues for 
migration. Less mobile or immobile species, such as mussels, cannot 
move to avoid low oxygen and are often killed during hypoxic 
events.\12\ While certain mature

[[Page 61216]]

aquatic animals can tolerate a range of dissolved oxygen levels that 
occur in the water, younger life stages of fish and shellfish often 
require higher levels of oxygen to survive.\13\ Sustained low levels of 
dissolved oxygen cause a severe decrease in the amount of aquatic life 
in hypoxic zones and affect the ability of aquatic organisms to find 
necessary food and habitat.
---------------------------------------------------------------------------

    \10\ NOAA. 2017. Ocean Facts: Are All Algal Blooms Harmful? 
National Oceanic and Atmospheric Administration, National Ocean 
Service. https://oceanservice.noaa.gov/facts/habharm.html.
    \11\ USEPA. 2017. What is Hypoxia and What Causes It? U.S. 
Environmental Protection Agency. <https://www.epa.gov/ms-htf/hypoxia-101>. Accessed December 2017.
    \12\ ESA. 2017. Hypoxia. Ecological Society of America <https://www.esa.org/esa/wp-content/uploads/2012/12/hypoxia.pdf>. Accessed 
December 2017.
    \13\ USEPA. 1986. Ambient Water Quality Criteria for Dissolved 
Oxygen Freshwater Aquatic Life. EPA-800-R-80-906. Environmental 
Protection Agency, Office of Water, Washington, DC.
---------------------------------------------------------------------------

    In freshwater lakes and reservoirs, blooms of cyanobacteria 
(sometimes referred to as blue-green algae),\14\ can produce toxins 
that have been implicated as the cause of a number of fish and bird 
mortalities.\15\ These toxins have also been tied to the death of pets 
and livestock that may be exposed through drinking contaminated water 
or grooming themselves after bodily exposure.\16\ Cyanobacterial toxins 
can also pass through normal drinking water treatment processes and 
pose an increased risk to humans or animals.\17\
---------------------------------------------------------------------------

    \14\ CDC. 2017. Harmful Algal Bloom (HAB)-Associated Illness. 
Centers for Disease Control and Prevention. <https://www.cdc.gov/habs/> Accessed December 2017.
    \15\ Ibelings, B.W. & K.E. Havens. 2008. Chapter 32: 
Cyanobacterial toxins: A qualitative meta-analysis of 
concentrations, dosage and effects in freshwater, estuarine and 
marine biota. In: Cyanobacterial Harmful Algal Blooms: State of the 
Science and Research Needs. From the Monograph of the September 6-
10, 2005 International Symposium on Cyanobacterial Harmful Algal 
Blooms (ISOC-HAB) in Durham, NC. <http://www.epa.gov/cyano_habs_symposium/monograph/Ch32.pdf>. Accessed August 19, 2010.
    \16\ WHOI. 2008. HAB Impacts on Wildlife. Woods Hole 
Oceanographic Institution. <http://www.whoi.edu/redtide/page.do?pid=9682>. Accessed December 2009.
    \17\ Carmichael, W.W. 2000. Assessment of Blue-Green Algal 
Toxins in Raw and Finished Drinking Water. AWWA Research Foundation, 
Denver, CO.
---------------------------------------------------------------------------

    Elevated nitrogen and phosphorus levels in lakes and reservoirs can 
impact human health and safety and otherwise detract from the outdoor 
recreational experience. For example, nutrient pollution in lakes 
typically promotes higher densities of phytoplankton, which can reduce 
the clarity of the water column to the detriment of swimmer safety. 
Cyanobacterial blooms frequently result in high algal toxin (e.g., 
microcystin) concentrations, leading to swimming beach closures and 
issuance of health advisories/warnings. In areas where recreation is 
determined to be unsafe because of algal blooms, warning signs often 
are posted to discourage human contact with the affected waters.
    Many other states, and countries for that matter, are experiencing 
problems with harmful algal blooms (HABs).18 19 Scientific 
assessments and numerous studies have shown an increase of HAB 
occurrence, distribution and persistence in the U.S. and globally in 
recent years.20 21 22 In a recent scientific assessment, 
reviewers found that observed increases in water temperatures alter the 
seasonal windows of growth and the geographic range of suitable habitat 
for freshwater toxin-producing harmful algae and marine toxin-producing 
harmful algae.\23\ These changes may increase the risk of exposure to 
waterborne pathogens and algal toxins that can cause a variety of 
illnesses. In addition, runoff from more frequent and intense extreme 
precipitation events may increasingly compromise recreational waters, 
shellfish harvesting waters, and sources of drinking water through 
increased prevalence of toxic algal blooms. An example of an algal 
bloom event occurred on August 10, 2017,\24\ when officials from the 
Oakland Country Health Division located near Detroit, Michigan issued a 
warning for residents and their pets to avoid two local lakes due to 
the presence of an algal bloom. People were advised to avoid contact 
with the water through recreation and to avoid drinking the water. In a 
July 7, 2017 article,\25\ the number of reports of harmful algal blooms 
affecting lakes and ponds in New York, as tracked by the New York State 
Department of Environmental Conservation, were increasing early in the 
season. Reducing nutrient input is one of the strategies lake managers 
are employing throughout the State to address the growing problem of 
algal blooms. Species of cyanobacteria commonly associated with 
freshwater algal blooms include: Microcystis aeruginosa, Anabaena 
circinalis, Anabaena flos-aquae, Aphanizomenon flos-aquae, and 
Cylindrospermopsis raciborskii. Under certain conditions, some of these 
species can release neurotoxins (affect the nervous system), 
hepatotoxins (affect the liver), lipopolysaccharide compounds inimical 
to the human gastrointestinal system, and tumor promoting 
compounds.\26\ One study showed that at least one type of cyanobacteria 
has been linked to cancer and tumor growth in animals.\27\
---------------------------------------------------------------------------

    \18\ FWCC. 2017. What is a Harmful Algal Bloom? <http://myfwc.com/research/redtide/general/harmful-algal-bloom/>. Accessed 
December 2017.
    \19\ Trevino-Garrison, I., DeMent, J., Ahmed, F.S., Haines-
Lieber, P., Langer, T., M[eacute]nager, H., Neff, J., van der Merwe, 
D., Carney, E. 2015. Human illnesses and animal deaths associated 
with freshwater algal blooms--Kansas. Toxins 7:353-366.
    \20\ Scientific American (2016) https://blogs.scientificamerican.com/guest-blog/toxic-algae-blooms-are-on-the-rise/.
    \21\ Lopez, C.B., Jewett, E.B., Dortch, Q., Walton, B.T., 
Hudnell, H.K. 2008. Scientific Assessment of Freshwater Harmful 
Algal Blooms. Interagency Working Group on Harmful Algal Blooms, 
Hypoxia, and Human Health of the Joint Subcommittee on Ocean Science 
and Technology. Washington, DC.
    \22\ Lopez, C.B., Dortch, Q., Jewett, E.B., Garrison, D. 2008. 
Scientific Assessment of Marine Harmful Algal Blooms. Interagency 
Working Group on Harmful Algal Blooms, Hypoxia, and Human Health of 
the Joint Subcommittee on Ocean Science and Technology. Washington, 
DC.
    \23\ USGCRP, 2016: The Impacts of Climate Change on Human Health 
in the United States: A Scientific Assessment. Crimmins, A., J. 
Balbus, J.L. Gamble, C.B. Beard, J.E. Bell, D. Dodgen, R.J. Eisen, 
N. Fann, M.D. Hawkins, S.C. Herring, L. Jantarasami, D.M. Mills, S. 
Saha, M.C. Sarofim, J. Trtanj, and L. Ziska, Eds. U.S. Global Change 
Research Program, Washington, DC, 312 pp.
    \24\ The Detroit News. Toxic algal blooms spotted in Waterford, 
White Lake by Stephanie Steinberg. August 10, 2017. http://www.detroitnews.com/story/news/environment/2017/08/10/toxic-algal-blooms-spotted-waterford-white-lake/104463128/.
    \25\ The New York Times. Beware the Blooms: Toxic Algae Found in 
Some City Ponds by Lisa W. Foderaro. July 7, 2017. https://www.nytimes.com/2017/07/07/nyregion/beware-the-blooms-toxic-algae-found-in-some-city-ponds.html.
    \26\ CDC. 2017. Harmful Algal Bloom (HAB)-Associated Illness, 
Centers for Disease Control and Prevention. <https://www.cdc.gov/habs/>. Accessed December 2017.
    \27\ Falconer, I.R. & A.R. Humpage. 2005. Health risk assessment 
of cyanobacterial (blue-green algal) toxins in drinking water. 
International Journal of Research and Public Health 2(1):43-50.
---------------------------------------------------------------------------

    Human health also can be impacted by disinfection byproducts 
(DBPs), formed when disinfectants (such as chlorine) used to treat 
drinking water react with organic carbon produced by algae in source 
waters. Some DBPs have been linked to rectal, bladder, and colon 
cancers; reproductive health risks; and liver, kidney, and central 
nervous system problems.28 29 In their study of 21 water 
supply lakes and reservoirs in New York, Callinan et al. (2013) 
concluded that ``autochthonous [algal] precursors contribute 
substantially to the DBP precursor pool in lakes and reservoirs and the 
. . . establishment of [numeric nutrient criteria] for the protection 
of [potable water supply] source waters is warranted and feasible.'' 
\30\
---------------------------------------------------------------------------

    \28\ USEPA. 2017. Drinking water Requirements for States and 
Public Water Systems, Public Water Systems, Disinfection Byproducts, 
and the Use of Monochloramine. U.S. Environmental Protection Agency. 
Accessed <https://www.epa.gov/dwreginfo/public-water-systems-disinfection-byproducts-and-use-monochloramine>. December 2017.
    \29\ National Primary Drinking Water Regulations: Stage 2 
Disinfectants and Disinfection Byproducts Rule, 40 CFR parts 9, 141, 
and 142. U.S. Environmental Protection Agency, FR 71:2 (January 4, 
2006). pp. 387-493. Available electronically at: <http://www.epa.gov/fedrgstr/EPA-WATER/2006/January/Day-04/w03.htm>. 
Accessed December 2009.
    \30\ Callinan, C.W., J.P. Hassett, J.B. Hyde, R.A. Entringer & 
R.K. Klake. 2011. Proposed nutrient criteria for water supply lakes 
and reservoirs. Journal of the American Water Works Association 
105(4):E157-E172.

---------------------------------------------------------------------------

[[Page 61217]]

    Implementation of nutrient criteria help to protect lakes and 
reservoirs from the negative effects of nutrient pollution, which 
frequently include, but are not limited to (a) the occurrence and 
spread of toxic algae, (b) the proliferation of certain fish species 
that are less desirable to sport anglers (i.e., ``rough'' fish), (c) a 
general decline in sensitive aquatic plant and animal populations, (d) 
the occurrence of taste and odor problems in drinking water derived 
from lakes and reservoirs, (e) Safe Drinking Water Act violations 
related to the occurrence of disinfection by-products (e.g., 
trihalomethanes, haloacetic acids) in finished drinking water, (f) a 
decline in waterbody transparency with accompanying recreational safety 
concerns, (g) the occurrence of unsightly scums and objectionable 
odors, (h) the depreciation of lakefront property values,\31\ and (i) 
an overall reduction in the functional life expectancy of reservoirs, 
with a corresponding loss of return on society's economic investment in 
these systems.
---------------------------------------------------------------------------

    \31\ USEPA. 2015. A Compilation of Cost Data Associated with the 
Impacts and Control of Nutrient Pollution, EPA 820-F-15-096, United 
States Environmental Protection Agency, May 2015.
---------------------------------------------------------------------------

3. Nutrient Pollution in Missouri Lakes and Reservoirs
    Lake water quality impairments attributable to nutrient pollution 
have not been quantified with any degree of precision in Missouri. 
Long-term monitoring data are available for about 10 percent of the 
State's classified lakes and reservoirs (representing approximately 90 
percent of overall lake acreage), and about 15 percent of these 
monitored waters already have EPA-approved numeric nutrient criteria.
    Missouri adopted site-specific chlorophyll a, total phosphorus and 
total nitrogen criteria for 25 lakes and reservoirs on July 1, 2009, 
which were approved by EPA on August 16, 2011. Currently, eleven of 
these waterbodies (44 percent) are listed for nutrient pollution-
related impairments. This percentage is consistent with nation-wide 
estimates of lakes in the most disturbed category obtained through the 
2012 National Lakes Assessment (NLA). Specifically, the NLA estimates 
that 40 percent of all lakes and reservoirs in the conterminous U.S. 
are considered most disturbed based on elevated phosphorus 
concentrations, and 35 percent are considered most disturbed based on 
elevated nitrogen concentrations (https://www.epa.gov/national-aquatic-resource-surveys/nla).
    MDNR acknowledges that lake and reservoir eutrophication is 
occurring at a detectable rate throughout much of the state.\32\ Over 
the past 20 or more years, chlorophyll a levels in monitored 
waterbodies have increased by an average of 3.5, 13, 28 and 2.6 
[micro]g/L in the Glaciated Plains, Osage Plains, Ozark Border and 
Ozark Highlands, respectively.\33\
---------------------------------------------------------------------------

    \32\ MDNR. 2016. Missouri Integrated Water Quality Report and 
Section 303(d) List, 2016. Missouri Department of Natural Resources, 
Jefferson City, Missouri. http://dnr.mo.gov/env/wpp/waterquality/303d/docs/2016-ir-305b-report.pdf.
    \33\ Id.
---------------------------------------------------------------------------

B. Statutory and Regulatory Background

    Section 303(c) of the CWA (33 U.S.C. Sec.  1313(c)) directs states 
and authorized tribes \34\ to adopt WQS for their navigable waters. 
Section 303(c)(2)(A) and EPA's implementing regulations at 40 CFR part 
131 require, among other things, that state WQS include the designated 
use or uses to be made of the waters and criteria that protect those 
uses. EPA regulations at 40 CFR Sec.  131.11(a)(1) provide that states 
and authorized tribes shall ``adopt those water quality criteria that 
protect the designated use'' and that such criteria ``must be based on 
sound scientific rationale and must contain sufficient parameters or 
constituents to protect the designated use. For waters with multiple 
use designations, the criteria shall support the most sensitive use.''
---------------------------------------------------------------------------

    \34\ Hereafter referred to as ``states and authorized tribes''. 
``State'' in the CWA and in this document, refers to a state, the 
District of Columbia, the Commonwealth of Puerto Rico, the U.S. 
Virgin Islands, Guam, American Samoa, and the Commonwealth of the 
Northern Mariana Islands. ``Authorized tribes'' refers to those 
federally recognized Indian tribes with authority to administer a 
CWA WQS program.
---------------------------------------------------------------------------

    Additionally, 40 CFR Sec.  130.10(b) provides that ``[i]n 
designating uses of a waterbody and the appropriate criteria for those 
uses, the state shall take into consideration the water quality 
standards of downstream waters and ensure that its water quality 
standards provide for the attainment and maintenance of the water 
quality standards of downstream waters.''
    States and authorized tribes also are required to hold one or more 
public hearings consistent with 40 CFR Sec.  25.5 to review their WQS 
at least once every three years and, as appropriate, modify or adopt 
new standards and to hold public hearings when revising or adopting new 
WQS. (See 33 U.S.C. Sec.  1313 (c)(1) and 40 CFR Sec.  131.20). Any new 
or revised WQS must be submitted to EPA for review and approval or 
disapproval. 33 U.S.C. Sec.  303(c)(2)(A), (3)). If EPA determines a 
state's new or revised standard does not meet the requirements of the 
CWA, EPA ``must specify the changes to meet such requirements.'' Sec.  
303(c)(3). If the state does not adopt such changes within ninety days, 
EPA ``shall promptly prepare and publish proposed regulations'' and 
promulgate any revised or new standard within ninety days unless the 
state has adopted and EPA has approved a WQS as meeting CWA 
requirements. Id.

C. Deriving and Expressing Numeric Nutrient Criteria

    Under CWA section 304(a), EPA periodically publishes criteria 
recommendations for use by states and authorized tribes in setting 
water quality criteria for particular parameters to protect the 
designated uses for their surface waters. Where EPA has published 
nationally-recommended criteria, states and authorized tribes have the 
option of adopting water quality criteria based on EPA's CWA section 
304(a) criteria guidance, section 304(a) criteria guidance modified to 
reflect site-specific conditions, or other scientifically defensible 
methods. (See 40 CFR 131.11(b)(1)). For nitrogen and phosphorus 
pollution, EPA finalized in 2001-2002 numeric nutrient criteria 
recommendations (i.e., total nitrogen, total phosphorus, chlorophyll a, 
and turbidity) for lakes and reservoirs, and for rivers and streams for 
most of the aggregated Level III Ecoregions in the United States. These 
were based on EPA's previously published series of peer-reviewed, water 
body specific technical guidance manuals regarding the development of 
numeric criteria for lakes and reservoirs \35\ and rivers and 
streams.\36\
---------------------------------------------------------------------------

    \35\ USEPA. 2000a. Nutrient Criteria Technical Guidance Manual: 
Lakes and Reservoirs. EPA-822-B-00-001. U.S. Environmental 
Protection Agency, Office of Water, Washington, DC.
    \36\ USEPA. 2000b. Nutrient Criteria Technical Guidance Manual: 
Rivers and Streams. EPA-822-B-00-002. U.S. Environmental Protection 
Agency, Office of Water, Washington, DC.
---------------------------------------------------------------------------

    In general, there are three types of empirical analyses that 
provide distinctly different, independent and scientifically 
defensible, approaches for deriving nutrient criteria from field data. 
These include (1) the ``reference condition approach,'' which derives 
criteria based on the observed water quality characteristics of 
minimally disturbed or least disturbed waterbodies, (2) the 
``mechanistic modeling approach,'' which employs mathematical 
representations of ecological systems, processes and parameters using 
equations that can be calibrated using site-specific data, and (3) the 
``stressor-response-based

[[Page 61218]]

modeling approach,'' \37\ which uses available data to estimate 
statistical relationships between nutrient concentrations and response 
(ecological, recreational, human health) measures relevant to the 
designated use to be protected. Each of these approaches is appropriate 
for deriving scientifically defensible numeric nutrient criteria. Other 
approaches may be appropriate depending on specific circumstances. 
Numeric nutrient criteria also may be based on well-established (e.g., 
peer-reviewed, published, widely recognized) nutrient response 
thresholds relating to the protection of a given designated use.\38\
---------------------------------------------------------------------------

    \37\ USEPA. 2010. Using Stressor-response Relationships to 
Derive Numeric Nutrient Criteria. EPA-820-S-10-001. U.S. 
Environmental Protection Agency, Office of Water, Washington, DC.
    \38\ USEPA. 2000a. Nutrient Criteria Technical Guidance Manual: 
Lakes and Reservoirs. EPA-822-B-00-001. U.S. Environmental 
Protection Agency, Office of Water, Washington, DC.
---------------------------------------------------------------------------

    EPA has long recommended that states adopt numeric criteria for 
total nitrogen (TN) and total phosphorus (TP),\39\ the nutrients that 
in excess can ultimately cause adverse effects on designated uses. For 
this reason, TN and TP are often referred to as ``causal'' parameters. 
However, EPA recognizes that the specific levels of TN and TP that 
adversely affect designated uses, including harm to aquatic life as 
indicated by various measures of ecological responses, may vary from 
waterbody to waterbody, depending on many factors, including 
geomorphology and hydrology among others. As a result, EPA has worked 
with several states as they developed a combined criterion approach 
that allows a state to further consider whether a waterbody is meeting 
designated uses when elevated TN and TP levels are detected. Under this 
approach, an exceedance of a causal variable, acts as a trigger to 
consider additional physical, chemical, and biological parameters that 
serve as indicators to determine protection or impairment of designated 
uses; these additional parameters are collectively termed ``response'' 
parameters.
---------------------------------------------------------------------------

    \39\ Id.
---------------------------------------------------------------------------

    EPA's articulation of this combined criterion approach \40\ is 
intended to apply when states wish to rely on response parameters to 
determine whether a designated use is impaired, once a causal variable 
has been found to be above an adopted threshold. As with any criteria, 
states should make clear at what point it has determined that a 
waterbody is meeting or not meeting its designated use. EPA has 
expressed that numeric values for all parameters must be set at levels 
that protect these uses (i.e., before adverse conditions occur that 
would require restoration).\41\
---------------------------------------------------------------------------

    \40\ This approach is sometimes referred to as a 
``bioconfirmation'' approach despite the fact that response 
parameters may not all be ``biological,'' although they typically do 
reflect biological activity.
    \41\ USEPA. Guiding Principles on an Optional Approach for 
Developing and Implementing a Numeric Nutrient Criterion that 
Integrates Casual and Response Parameters. September 2013.
---------------------------------------------------------------------------

    EPA has worked extensively with states that have adopted a combined 
criterion approach, resulting in CWA section 303(c) approvals of 
combined criterion approaches for Florida's streams,42 43 
Minnesota's rivers and streams,\44\ and Vermont's lakes and 
reservoirs.\45\ Although each of these combined criterion approaches 
differ from one another in terms of the applicable causal parameters 
and suite of response parameters as applied to various waterbody types, 
the combined criterion construction can provide greater precision when 
there is heightened variability in waterbodies' responses to nutrients.
---------------------------------------------------------------------------

    \42\ USEPA. Letter from James D. Giattina, Director, Water 
Protection Division, EPA Region 4, to Herschel T. Vinyard, 
Secretary, Florida Department of Environmental Protection. November 
30, 2012.
    \43\ USEPA. Letter from James D. Giattina, Director, Water 
Protection Division, EPA Region 4, to Herschel T. Vinyard, 
Secretary, Florida Department of Environmental Protection. June 27, 
2013.
    \44\ USEPA. Letter from Tinka Hyde, Director, Water Division, 
EPA Region 5, to Commissioner John Line Stine, Minnesota Pollution 
Control Agency. January 23, 2015.
    \45\ USEPA. Letter from Kenneth Moraff, Director, Office of 
Ecosystem Protection, EPA Region 1 to Alyssa Schuren, Commissioner, 
Vermont Department of Environmental Conservation. September 15, 
2015.
---------------------------------------------------------------------------

    EPA notes that once appropriate numeric criteria are developed, 
assessment of the impairment status of individual water bodies is 
dependent on data; this is true for any set of numeric criteria 
addressing any pollutant. EPA further recognizes that it is the 
responsibility of States to determine the pace and prioritization of 
data collection, as this is primarily an implementation issue rather 
than a criteria development issue. However, EPA recommends that states 
consider such implementation issues at the time of criteria development 
as this may lead to a more successful water quality standards program 
generally. In the case of nutrient criteria, EPA has recommended that 
states interested in this approach develop a biological assessment 
program that can measure biological responses and other nutrient-
related response parameters with confidence through a robust monitoring 
program to account for spatial and temporal variability to document the 
effects of nutrient pollution. EPA reiterates, however, that States 
have significant discretion in determining the appropriate pace and 
prioritization of such a monitoring program.
    In developing combined criteria, States and EPA have previously 
identified the following as response parameters that are indicative of 
nutrient pollution in streams: measures of primary productivity (e.g. 
benthic chlorophyll a, percent cover of macrophytes), measures of algal 
assemblage (e.g. algal assemblage indices), and measures of ecosystem 
function (e.g. continuously monitored pH and dissolved oxygen). EPA 
recognizes that this may not be an exhaustive list of appropriate 
response parameters. The approach is generally applicable to lakes and 
reservoirs, as well as other waterbody types. For lakes and reservoirs, 
chlorophyll a has typically been measured as sestonic (open water) 
concentration rather than as a benthic (bottom surface) concentration. 
Appropriate biological response parameters should directly link 
nutrient concentrations to the protection of designated uses. The 
appropriate type and quantity of response parameters may vary by state, 
ecosystem, and waterbody type.
    In previous guidance, EPA has recommended that a combined criterion 
approach should make clear the impairment status of waterbodies in the 
following situations.\46\ Specifically, EPA has recommended that if all 
causal and response parameters are met, then the water quality 
criterion is met and the waterbody is deemed to be meeting its 
designated uses. If all response parameters are met, but one or more of 
the causal parameters is exceeded, then the criterion is met and the 
waterbody is deemed to be meeting its designated uses (though the state 
may wish to flag this water body for further scrutiny in the future). 
If a causal parameter is exceeded and any applicable response parameter 
is exceeded, then the criterion is not met and the waterbody is deemed 
to not be meeting its designated uses. If a causal parameter is 
exceeded and data are unavailable for any applicable response 
parameters, then the criterion is not met and the waterbody is deemed 
to not be meeting its designated uses. If a causal parameter is not 
exceeded but an applicable response variable is exceeded, then the 
criterion is not met and the waterbody is deemed to not be meeting its 
designated uses (in this scenario, further

[[Page 61219]]

investigation may be warranted to determine if nutrient pollution is 
the cause).
---------------------------------------------------------------------------

    \46\ USEPA. Guiding Principles on an Optional Approach for 
Developing and Implementing a Numeric Nutrient Criterion that 
Integrates Casual and Response Parameters. September 2013.
---------------------------------------------------------------------------

    One situation deserves special consideration. If a causal parameter 
is exceeded and data are unavailable for any applicable response 
parameters, EPA has previously recommended that the criterion be deemed 
not met and the waterbody be deemed to not be meeting its designated 
uses. Under one of EPA's co-proposed approaches (which mirrors the 
State's 2017 proposal), such waterbodies would be deemed 
``undetermined'' with respect to impairment status. Under the other co-
proposed approach, which matches EPA's prior recommendations, the water 
body is deemed to be impaired, until all response variables have been 
assessed, at which point the water body status may be changed to non-
impaired if no response variable is exceeded. EPA has recommended this 
approach in the past on the grounds that an exceedance of a causal 
variable will generally correlate with impairment of aquatic life uses, 
but we preserve the flexibility for states to conclude that a waterbody 
is not impaired if information indicates the absence of a response in 
the waterbody supporting the conclusion that the use is being 
protected. EPA recognizes there are alternative views of how this 
comports with requirements that criteria be based on a sound scientific 
rationale and protective of designated uses, believing if data on some 
response variables are missing, then it may not be known whether the 
water body is meeting its designated use or not, and an 
``undetermined'' status with respect to impairment may be appropriate. 
EPA solicits comment on whether response variables are the best 
indicators of impairment or non-impairment, and the science policy 
considerations relevant to determining whether a water body is meeting 
its designated use if data on some or all response variables are 
missing.
    The approach described above ensures protection of designated uses 
by taking into account critical information about the pollutant load in 
the waterbody, as well as the response. Although the terminology of the 
combined criterion approach more closely aligns with assessment and 
listing terminology, the combined criterion is also the applicable WQS 
for NPDES permitting purposes whereby permits must contain limits for 
any pollutant parameters that are or may be discharged at levels that 
will cause, have reasonable potential to cause, or contribute to an 
excursion above any WQS (40 CFR 122.44(d)(1)).

D. Missouri's 2009 Nutrient Criteria Submission and EPA's Clean Water 
Act Section 303(c) Action

    On November 5, 2009, Missouri submitted revised WQS containing 
nutrient criteria for a large subset of the State's classified lakes 
and reservoirs. These standards contained the following language at 10 
CSR 20-7.031(4)(N)2: ``This [nutrient criteria] rule applies to all 
lakes and reservoirs that are waters of the state and that are outside 
the Big River Floodplain Ecoregion and have an area of at least ten 
(10) acres during normal pool.'' Table G in Missouri's WQS regulations 
listed 453 classified lakes and reservoirs, 25 of which were deemed 
``high quality'' and were assigned site-specific nutrient criteria 
separately in Table M. Of the remaining waters, 96 were smaller than 
ten acres and/or located in the Big River Floodplain Ecoregion and 
exempted from the application of nutrient criteria under 10 CSR 20-
7.031(4)(N)2. Conversely, 332 lakes and reservoirs not listed in Table 
M were subject to the application of nutrient criteria under 10 CSR 20-
7.031(4)(N)2 and (4)(N)3 at the time Missouri submitted its nutrient 
criteria to EPA. On August 16, 2011, EPA approved all nutrient criteria 
assigned to the 25 waterbodies listed in Table M but disapproved 
nutrient criteria that would have applied to the remaining waterbodies. 
Additionally, EPA disapproved site-specific criteria for total 
phosphorus assigned to the tributary arms of two large reservoirs (Lake 
of the Ozarks and Table Rock Lake) per 10 CSR 20-7.031(4)(N)3.A.IV.
    The disapproved water quality standards defined ``prediction 
values,'' ``reference values'' and ``site specific-values'' and derived 
total phosphorus (TP) criteria based on how these values compared to 
one another. This approach involved a set of input variables and site-
specific data requirements. For example, the regulation established 
that TP prediction values for lakes and reservoirs in the Plains must 
be calculated based on site-specific coefficients for the (a) 
percentage of watershed originally in prairie, (b) hydraulic residence 
time in years, and (c) dam height in feet. To apply the appropriate TP 
criterion, the State would have had to know how the TP prediction value 
compared to both the TP reference value and the actual (empirically 
determined) TP concentration. Total nitrogen (TN) and chlorophyll a 
criteria were calculated as multiples of the selected TP criterion.
    EPA's disapproval action was based on a determination that 
Missouri's proposal did not include the data and other necessary 
information needed for EPA to independently reproduce the State's work 
and that the State had failed to demonstrate that the criteria would 
protect the designated aquatic life support and recreational uses as 
required by 40 CFR 131.6(b) and (c).\47\
---------------------------------------------------------------------------

    \47\ US EPA. (2011) Letter to Sara Parker Pauley (Director, 
Missouri Department of Natural Resources) from Karl Brooks (USEPA 
Region 7), Decision document on Missouri Water Quality Standards, 
August 16, 2011.
---------------------------------------------------------------------------

    On March 19, 2014, Missouri submitted revised water quality 
standards (the designated uses component) that incorporated, for the 
first time, the Missouri Use Designation Dataset (MUDD) (10 CSR 20-
7.031(2)(E); see also Table G of WQS which references the MUDD \48\). 
This dataset assigned designated uses to the State's classified lakes 
and reservoirs (and streams) and was approved by EPA on October 22, 
2014. Altogether, MUDD identified 3,081 waterbody segments, including 
2,757 lakes and reservoirs, and assigned the following designated uses 
to these waters: aquatic life support, whole body contact recreation, 
secondary contact recreation, fish consumption, livestock and wildlife 
watering, irrigation, and industrial water supply. In addition to these 
uses, 123 lakes and reservoirs are also designated in the 2014 MUDD 
dataset for drinking water supply. Missouri also revised its water 
quality standards to provide that its specific criteria applies to all 
waters consistent with the designated uses identified in Table G and 
MUDD. 10 CSR 20-7.031(5). EPA approved this change on November 17, 
2015. EPA's proposed rule addresses the same generic class of waters 
included in Missouri's disapproved rule. However, consistent with 
Missouri's subsequent actions, EPA's proposal would apply to a larger 
group of enumerated lakes and reservoirs, specifically those in Table G 
and MUDD that are ten acres or more, not located in the Big River 
Floodplain Ecoregion, and not otherwise listed in Table M of the WQS. 
This includes 967 waterbodies. EPA requests comment on whether this 
scope is appropriate for the current rule.
---------------------------------------------------------------------------

    \48\ The Water Body Name, Missouri Use Designation Dataset 
Version 1.0, August 20, 2013 (8202013 MUDD V1.0), refers to all 
lakes in the Missouri Use Designation Dataset Version 1.0, August 
20, 2013, that are not otherwise listed in Table G.
---------------------------------------------------------------------------

E. Missouri Coalition for the Environment (MCE) Lawsuit and Consent 
Decree

    On February 24, 2016, the Missouri Coalition for the Environment 
Foundation (MCE) filed a lawsuit alleging that EPA failed to perform 
its

[[Page 61220]]

nondiscretionary duty to propose and promulgate new or revised water 
quality standards for lakes and reservoirs in Missouri after 
disapproving the State's submission in 2011. On December 1, 2016, EPA 
entered into a consent decree with MCE that stipulates that EPA shall 
sign a notice of proposed rulemaking by December 15, 2017, to address 
EPA's 2011 disapproval, unless the State submits and EPA approves new 
or revised standards that address the disapproval on or before December 
15, 2017; and that EPA shall sign a notice of final rulemaking on or 
before December 15, 2018, unless the State submits and EPA approves new 
or revised standards that address the disapproval. In the years 
following the 2011 disapproval action, EPA has endeavored to work 
closely with Missouri to develop approvable nutrient criteria.

F. Missouri's 2017 Proposed Nutrient WQS

    On October 16, 2017, MDNR continued to develop revised numeric 
nutrient criteria and formally issued its proposed WQS that are 
intended to address EPA's August 16, 2011 disapproval. Based on EPA's 
examination of the State's proposed rule, Missouri has characterized 
its revised nutrient WQS as a combined criterion. Missouri's proposed 
rule applies to lakes and reservoirs.\49\ The State's lakes and 
reservoirs are impounded and have been assigned an aquatic life use of 
either: Warm water habitat, cool water habitat, or cold water habitat. 
Each subcategory is defined as ``waters in which naturally-occurring 
water quality and habitat conditions allow [for] the maintenance of a 
wide variety of [warm, cool or cold water] biota.'' \50\ The State 
takes the position that ``health of sport fish populations can be 
interpreted as an indicator of overall ecosystem health and the 
presence of a ``wide variety'' of aquatic biota.'' \51\ Missouri's 
proposed rule establishes three ecoregions and sets forth for each 
ecoregion chl-a criteria above which waters would be deemed impaired, 
and a combination of TN, TP, and chl-a ``screening values'' and five 
``eutrophication impacts'' (i.e., response parameters) where a 
waterbody would be deemed impaired if at least one screening value and 
at least one eutrophication impact are exceeded in the same year. When 
data are unavailable for the eutrophication impacts despite information 
indicating that at least one screening value is exceeded, Missouri 
intends waters to be listed on Category 3 of the 305(b)/303(d) 
Integrated Report, meaning there is insufficient information to 
determine impairment status. In Missouri's expression of the combined 
criterion approach, the chl-a parameter functions as both a screening 
value, requiring evaluation of the eutrophication impacts, and at a 
higher level as a stand-alone criterion that would determine in and of 
itself that a water body is impaired, without the need to further 
assess eutrophication impacts. If chl-a is exceeded at the screening 
level but there is inadequate information on the other response 
variables, the water is placed in category 3 and not listed as 
impaired.
---------------------------------------------------------------------------

    \49\ See 10 CSR 20-7.031(5) and the October 2017 draft language 
proposed for 10 CSR 20-7.031(5)(N)(2) (``This rule applies to all 
lakes that are waters of the state and have an area of at least ten 
(10) acres during normal pool conditions. Big River Floodplain lakes 
shall not be subject to these criteria'').
    \50\ 10 CSR 20-7.031(1)(C)1.A.VI, B.V and C.V.
    \51\ See Missouri Department of Natural Resources, Rationale for 
Missouri Reservoir Nutrient Criteria Development, November 2016, 
Section 6.1, pages 33-39.
---------------------------------------------------------------------------

Table 2. Excerpts From Missouri's October 16, 2017 Nutrient Proposal

                 Table L--Lake Ecoregion Chl-a Criteria and Nutrient Screening Values ([mu]g/L)
----------------------------------------------------------------------------------------------------------------
                                                                            Screening Values ([mu]g/L)
                 Lake Ecoregion                        Chl-a     -----------------------------------------------
                                                     Criterion          TP              TN             Chl-a
----------------------------------------------------------------------------------------------------------------
Plains..........................................              30              49             843              18
Ozark Border....................................              22              40             733              13
Ozark Highland..................................              15              16             401               6
----------------------------------------------------------------------------------------------------------------
5. Lakes with water quality that exceed Nutrient Criteria identified in Tables L and M are to be deemed impaired
  for excess nutrients.
6. Lakes with water quality that exceed screening values for Chl-a, TN, or TP are to be deemed impaired for
  excess nutrients if any of the following eutrophication impacts are documented for the respective designated
  uses within the same year. Eutrophication impacts for aquatic life uses include:
(I) Occurrence of eutrophication-related mortality or morbidity events for fish and other aquatic organisms;
(II) Epilimnetic excursions from dissolved oxygen or pH criteria;
(III) Cyanobacteria counts in excess of 100,000 cells per milliliter (cells/ml);
(IV) Observed shifts in aquatic diversity attributed to eutrophication; and
(V) Excessive levels of mineral turbidity that consistently limit algal productivity during the period May 1-
  September 30

    At the time of this proposal, Missouri's proposal is still under 
consideration and the State has not submitted to EPA for CWA 303(c) 
review a final rule with supporting information to address EPA's 2011 
disapproval.

III. Proposed Nutrient Combined Criterion for Lakes and Reservoirs in 
Missouri

A. Proposed Combined Criterion Approaches

    Today EPA is proposing two alternatives to establish nutrient 
criteria in a combined criterion approach to address its 2011 
disapproval. Under the first alternative, EPA proposes nutrient 
protection values and eutrophication impact factors in a combined 
criterion approach. Under the second alternative, EPA proposes a 
combined criterion approach that would mirror the State of Missouri's 
October 2017 proposal for lake nutrient water quality standards. EPA 
seeks public comment on the two alternatives described below in light 
of the federal regulations at 40 CFR part 131.11 requiring that 
criteria must be based on a sound scientific rationale and protective 
of the designated uses of the waters.

B. Proposed Combined Criterion Alternative 1

    Alternative 1 is presented in Table 3 below and appears as 
regulatory text at the end of this proposal.

[[Page 61221]]

    Table 3--Alternative 1 Lake Ecoregion Nutrient Protection Values ([micro]g/L) and Eutrophication Impacts
----------------------------------------------------------------------------------------------------------------
                         Lake Ecoregion                                 TP              TN             Chl-a
----------------------------------------------------------------------------------------------------------------
Plains..........................................................              44             817              14
Ozarks..........................................................              23             500             7.1
----------------------------------------------------------------------------------------------------------------
(1) Lake and reservoir water quality must not exceed nutrient protection values for chlorophyll-a. (2) Lake and
  reservoir water quality must also not exceed nutrient protection values for total nitrogen and total
  phosphorus unless each of the following eutrophication impacts are evaluated and none occur within the same
  three-year rolling average period: (I) Eutrophication-related mortality or morbidity events for fish and other
  aquatic organisms; (II) An excursion from the DO or pH criteria in Missouri water quality standards applicable
  for Clean Water Act purposes; (III) Cyanobacteria counts equal to or greater than 100,000 cells per ml; (IV)
  Observed shifts in aquatic diversity directly attributable to eutrophication; or (V) Excessive levels of
  mineral turbidity that consistently limit algal productivity during the period May 1-September 30, or Secchi
  disk measurements of turbidity equal to or less than EPA's recommended Level III Ecoregions IX (1.53 m) or IX
  (2.86 m).

    Alternative 1 is comprised of nutrient protection values and 
eutrophication impacts. Nutrient protection values are defined 
similarly as Missouri defines their ``screening values'': maximum 
ambient concentrations of TP, TN, and chl-a based on the three-year 
rolling average geometric mean of nutrient data collected April through 
September. EPA has chosen the term ``protection values,'' rather than 
``causal'' or ``screening'' values, to emphasize that in general, lakes 
and reservoirs that do not exceed these values may be assumed to meet 
designated uses without further assessment of eutrophication impacts. 
However, EPA recognizes, consistent with the logic of the combined 
criteria approach, that exceedance of such values does not necessarily 
mean that a water body is impaired. Alternative 1 uses nutrient 
protection values for TN, TP, and chl-a derived using a reference 
condition approach for the Plains ecoregion and a combined Ozarks 
ecoregion described in detail in the following section. These values 
are based on a reference condition approach using the 75th percentile 
of a distribution of values from a population of least disturbed lakes 
in each of the two ecoregions (Plains and Ozarks). The nutrient 
protection values for chl-a in Alternative 1 function as stand-alone 
criteria independent from the TN and TP protection values and other 
eutrophication impact factors. This approach gives additional weight to 
chl-a as a key early response indicator of adverse impact from excess 
nitrogen and phosphorus.
    Under Alternative 1, lake and reservoir water quality must not 
exceed protection values for TN or TP unless each of the eutrophication 
impacts are evaluated and data demonstrate that none occur within the 
same three-year rolling average period as a TN or TP exceedance. EPA 
included this presumption to address potential for data gaps for 
response parameters.\52\ As such, when TN and TP levels are exceeded, 
the designated uses would be considered impaired unless sufficient 
information exists demonstrating no eutrophication impacts are 
occurring. Eutrophication impacts include: (I) Eutrophication-related 
mortality or morbidity events for fish and other aquatic organisms; 
(II) An excursion from the dissolved oxygen (DO) or pH criteria in 
Missouri water quality standards applicable for Clean Water Act 
purposes; (III) Cyanobacteria counts equal to or greater than 100,000 
cells per ml; (IV) Observed shifts in aquatic diversity directly 
attributable to eutrophication; or (V) Excessive levels of mineral 
turbidity that consistently limit algal productivity during the period 
May 1-September 30, or Secchi disk measurements of turbidity equal to 
or less than EPA's recommended Level III Ecoregions IX (1.53 m) or IX 
(2.86 m). Alternative 1 does not include a qualifier of ``epilimnetic'' 
with respect to excursion of DO or pH criteria to reflect that aquatic 
habitat extends beyond the surficial layer of lakes and reservoirs, and 
to be consistent with the State's currently approved DO and pH 
criteria. Alternative 1 includes specific Secchi disk measurement 
thresholds as part of the turbidity component to provide a means of 
quantifying this eutrophication impact factor.\53\
---------------------------------------------------------------------------

    \52\ EPA recognizes that there are differences of opinion on 
whether addressing such data gaps is necessary in a combined 
criteria approach and that this presumption is not a feature of the 
co-proposed Alternative 2.
    \53\ Secchi disk measurement thresholds could be those presented 
in in EPA's Level III ecoregional criteria documents (1.53 m for 
Ecoregion IX and 2.86 for Ecoregion XI). See USEPA. December 2000. 
Ambient Water Quality Criteria Recommendations, Information 
Supporting the Development of State and Tribal Nutrient Criteria 
Lakes and Reservoirs in Nutrient Ecoregion IX. EPA 822-B-00-011. 
https://www.epa.gov/sites/production/files/documents/lakes9.pdf and 
USEPA. December 2000. Ambient Water Quality Criteria Recommendations 
Information Supporting the Development of State and Tribal Nutrient 
Criteria Lakes and Reservoirs in Nutrient Ecoregion XI. EPA 822-B-
00-012. https://www.epa.gov/sites/production/files/documents/lakes11.pdf. An alternative Secchi disk measurement could be 1 meter 
based on the hypereutrophic boundary identified in Carlson, R.E. and 
J. Simpson. 1996. A Coordinator's Guide to Volunteer Lake Monitoring 
Methods. North American Lake Management Society. 96 pp., and further 
supported by the data used to derive reference condition values. A 
third set of alternatives appears in the Technical Support Document 
accompanying this rule describing reference condition values for 
Missouri lakes.
---------------------------------------------------------------------------

C. Derivation of Nutrient Protection Values for Alternative 1

    EPA requests comment on a set of nutrient protection values as 
derived below. This methodology considered the water quality 
characteristics of lakes and reservoirs located in watersheds with 
comparatively low levels of human disturbance. This methodology, known 
as the reference condition approach, comports with longstanding Agency 
guidance \54\ and builds on earlier collaborative efforts in the four-
state region.\55\ This approach could be implemented using the State's 
existing water quality dataset \56\ and key geographical concepts and 
interpretations supported previously by the State.\57\
---------------------------------------------------------------------------

    \54\ USEPA. 2000. Nutrient Criteria Technical Guidance Manual: 
Lakes and Reservoirs. EPA-822-B00-001. U.S. Environmental Protection 
Agency, Office of Water, Washington DC.
    \55\ RTAG. 2011. Nutrient Reference Condition Identification and 
Ambient Water Quality Benchmark Development Process: Freshwater 
Lakes and Reservoirs within USEPA Region 7. Regional Technical 
Advisory Group. Kansas Biological Survey, University of Kansas, 
Lawrence, KS.
    \56\ Obrecht, D. 2015. Statewide Lake Assessment Program. 
Quality assurance project plan. School of Natural Resources, 
University of Missouri, Columbia, MO.
    Thorpe, A. 2015. The Lakes of Missouri Volunteer Program. 
Quality assurance project plan. School of Natural Resources, 
University of Missouri, Columbia, MO.
    \57\ Nigh, T.A. and W.A. Schroeder. 2002. Atlas of Missouri 
Ecoregions. Missouri Department of Conservation, Jefferson City, MO.
---------------------------------------------------------------------------

    Protecting a waterbody at reference conditions should inherently 
protect all designated uses, and therefore, should support the most 
sensitive use.58 59 EPA

[[Page 61222]]

is unaware of compelling scientific evidence that would suggest that 
the reference condition approach employed here would not protect 
Missouri's aquatic life, recreation, and drinking water designated 
uses, though EPA is not suggesting that there are no other approaches 
to protect applicable designated uses. EPA believes that the reference 
condition approach described here also comports with the State's 
regulatory definition for the aquatic life support use. This definition 
recognizes three subcategories under the aquatic life support header: 
Warm water habitat, cool water habitat, and cold water habitat.\60\ 
Each subcategory is described as ``waters in which naturally-occurring 
water quality and habitat conditions allow [for] the maintenance of a 
wide variety of [warm, cool or cold water] biota.'' This description is 
explicitly applied to lakes and reservoirs (10 CSR 20-
7.031(1)(C)1.A.VI, B.V and C.V and 10 CSR 20-7.031(2)). Moreover, it 
links the aquatic life support use to the naturally occurring water 
quality condition, which is approximated by the reference condition. In 
the context of ambient nutrient concentrations, the accuracy of this 
approximation varies among regions depending on the prevailing extent 
of disturbance to natural land cover and other factors.\61\ Given the 
prevailing level of disturbance to natural land cover in Missouri, this 
approach could use nutrient protection values based on the least 
disturbed reference condition, which represents the best remaining 
condition in Missouri, rather than the historical or minimally 
disturbed reference condition.\62\
---------------------------------------------------------------------------

    \58\ USEPA. 2000a. Nutrient Criteria Technical Guidance Manual: 
Lakes and Reservoirs. EPA-822-B-00-001. U.S. Environmental 
Protection Agency, Office of Water, Washington, DC.
    \59\ Grubbs, Geoffrey. 2001. Development and Adoption of 
Nutrient Criteria into Water Quality Standards. WQSP-01-01. Policy 
memorandum signed on November 14, 2001, by Geoffrey Grubbs, 
Director, Office of Science and Technology, U.S. Environmental 
Protection Agency, Washington, DC.
    \60\ The same nutrient criteria apply to all three subcategories 
based on the way EPA aggregated data for purposes of deriving 
protective criteria using a reference condition approach.
    \61\ EPA Technical Support Document for this rule, Nutrient 
Criteria Recommendations for Lakes in Missouri, Section 2.4.
    \62\ Stoddard, J.L., D.P. Larsen, C.P. Hawkins, R.K. Johnson and 
R.H. Norris. 2006. Setting expectations for the ecological 
conditions of streams: The concept of reference condition. 
Ecological Applications 16:1267-1276. Stoddard et al. (2006) 
suggested that waters exhibiting comparatively little degradation 
could be placed into one of two categories: Minimally disturbed 
systems (those little affected by human actions); and least 
disturbed systems (those exhibiting the best remaining condition in 
a region widely impacted by human actions). The term historical was 
used by the same authors to denote a condition occurring at some 
specified point in the past (e.g., immediately prior to European 
settlement).
---------------------------------------------------------------------------

    In developing this Alternative 1 approach, EPA initially considered 
all readily available water quality data (i.e., TN, TP, total 
chlorophyll, chlorophyll a, Secchi transparency data) for lakes and 
reservoirs in Missouri. These records were accessed using the federal 
Water Quality Portal (WQP), which is maintained jointly by the EPA, the 
U.S. Geological Survey (USGS), and the National Water Quality 
Monitoring Council. The WQP integrates publicly available data from the 
EPA Storage and Retrieval Data Warehouse, the USGS National Water 
Information System, and the U.S. Department of Agriculture's 
Agricultural Research Database System.
    EPA subsequently reviewed sampling and analytical protocols 
employed by the various governmental agencies, academic institutions 
and private entities (e.g., consulting firms) contributing to the 
above-mentioned databases. Based on this review, EPA elected to confine 
its analysis to data derived from the Missouri Statewide Lake 
Assessment Program (SLAP) and the Lakes of Missouri Volunteer 
Monitoring Program (LMVP), both overseen by the University of Missouri-
Columbia Limnology Laboratory. This decision ensured that all water 
quality data used in the reference condition analysis were obtained 
using comparable field and analytical methods and derived from the same 
sampling period, 1989-2015. The dataset was narrowed further by 
removing data for all waters smaller than ten acres or located in the 
Big River Floodplain Ecoregion, consistent with the scope of waters 
covered by this proposal. For consistency, only data from the main body 
of these lakes/reservoirs (i.e., from deeper, open water locations) 
were used in the reference condition analysis. Overall, this effort 
yielded suitable long-term data for 170 lakes/reservoirs in Missouri 
(119 located in the Plains Ecoregion and 51 located in the Ozarks 
Ecoregion). As explained in the Technical Support Document accompanying 
this proposal, EPA combined data obtained from the Ozark Border and the 
Ozark Highlands ecoregions identified in the State proposal because 
lakes in these two regions exhibited statistically similar 
concentrations for chlorophyll, total phosphorus and total nitrogen.
    In identifying candidate (least disturbed) reference sites, EPA 
used the following criteria as an initial screen to identify least 
disturbed waters, all previously included in the State's 2009 WQS 
submittal.
     Cropland and urban land combined accounted for less than 
twenty percent of the watershed land use.63 64 This 
criterion was applied by EPA in all instances.
---------------------------------------------------------------------------

    \63\ Jones, J.R., M. F. Knowlton, and D.V. Obrecht. 2008. Role 
of land cover and hydrology in determining nutrients in mid-
continent reservoirs: implications for nutrient criteria and 
management. Lake and Reservoir Management. 24:1, 1-9, DOI:10.1080/
07438140809354045.
    \64\ W. K. Dodds and R. M. Oakes. 2004. A technique for 
establishing reference nutrient concentrations across watersheds 
affected by humans. Limnology and Oceanography: Methods. 2:333-341.
---------------------------------------------------------------------------

     No point source, to include concentrated animal feeding 
operation (CAFO), was located in the watershed. EPA applied this 
criterion to CAFOs and major wastewater treatment plants (WWTPs) 
permitted under the National Pollutant Discharge Elimination System 
(NPDES). Non-discharging facilities and smaller discharging facilities 
(e.g., mobile home parks) were evaluated individually based on their 
location in the watershed and other factors.
     If located in the Plains, more than fifty percent of the 
watershed was covered by grassland.\65\ In applying this threshold, EPA 
considered grassland and all other forms of native land cover (e.g., 
forest, marshland).
---------------------------------------------------------------------------

    \65\ J.R. Jones, M.F. Knowlton, D.V. Obrecht, and E.A. Cook. 
2004. Importance of landscape variables and morphology on nutrients 
in Missouri reservoirs. Canadian Journal of Fisheries and Aquatic 
Science. 61:1503-1512.
---------------------------------------------------------------------------

     If located in the Ozark Highlands, more than fifty percent 
of the watershed was forested. Forests in the Ozark Highlands are the 
equivalent to grasslands in the Plains in terms of native land cover 
and associated nutrient delivery. This selection criterion was applied 
by EPA to the Ozark Highlands and the adjoining Ozark Border, which 
collectively comprise the Ozarks Ecoregion.\66\
---------------------------------------------------------------------------

    \66\ EPA Technical Support Document for this rule, Nutrient 
Criteria Recommendations for Lakes in Missouri, Section 6.1.
---------------------------------------------------------------------------

    In order to identify waters meeting this initial screening 
criteria, EPA obtained digital watershed polygons from USGS's National 
Hydrography Dataset and a separate dataset maintained by the University 
of Missouri-Columbia. In about five cases, polygons were not available 
in either dataset and had to be digitized in ArcGIS.\67\ NHDPlus-V2 
flowlines and medium resolution NHD (1:100,000 scale) elevation-derived 
catchments were used to identify the watersheds for each lake/
reservoir. In cases where a watershed was represented by more than one 
catchment, the catchments were dissolved into one polygon. For many of 
the smaller lakes/reservoirs, watersheds were defined using the Water 
Erosion Prediction Project

[[Page 61223]]

(WEPP) model.\68\ The Zonal Tabulate Area tool in ArcGIS Spatial 
Analyst and the 2014 edition of the 2011 National Land Cover 
(www.mrlc.gov) were used to calculate the percentage of each watershed 
in specific land cover types. These percentages, along with ArcGIS-
generated maps depicting the locations of permitted point sources and 
CAFOs, were used to identify lakes/reservoirs meeting the 
aforementioned selection criteria.
---------------------------------------------------------------------------

    \67\ ArcGIS is a digital geographic information system (GIS) 
used for creating and using maps, compiling geographic data, 
analyzing mapped information, sharing and discovering geographic 
information, and managing geographic information in a database form.
    \68\ Flanagan, D.C., J.R. Frankenberger, T.A. Cochrane, C.S. 
Renschler & W.J. Elliot. 2011. Geospatial application of the water 
erosion prediction (WEPP) model. International Symposium on Erosion 
and Landscape Evolution (ISELE), Anchorage, Alaska. September 18-21, 
2011. ISELE Paper Number 11084.
    Flanagan, D.C., J.R. Frankenberger, T.A. Cochrane, C.S. 
Renschler & W.J. Elliot. 2013. Geospatial application of the water 
erosion prediction (WEPP) model. Transactions of the American 
Society of Agricultural and Biological Engineers 50(2):591-601.
---------------------------------------------------------------------------

    After this initial screening exercise, EPA then subjected the 
identified candidate watersheds/lakes to further evaluation using 
aerial imagery, NPDES permit records, Missouri Department of 
Conservation (MDC) conservation area reports, and other available 
sources of information. EPA removed watersheds and lakes from further 
consideration if they (1) received substantial drainage from the Big 
River Floodplain Ecoregion (out of scope); (2) exhibited extensive 
shoreline residential development; (3) had received historical or 
recent manure applications from nearby feedlots; (4) had undergone 
deliberate (fisheries oriented) fertilization efforts; and (5) had been 
situated in an area of formerly cultivated fields.\69\ The latter four 
reasons relate to factors relate to disturbance.
---------------------------------------------------------------------------

    \69\ EPA Technical Support Document for this rule, Nutrient 
Criteria Recommendations for Lakes in Missouri, Section 6.1.
---------------------------------------------------------------------------

    Additionally, three isolated waterbodies in the Plains exhibited 
median chlorophyll a concentrations exceeding 40 [micro]g/L.\70\ Based 
on earlier studies, hypereutrophic waters of this kind are not 
representative of the reference condition in the Central Irregular 
Plains \71\, a region encompassing much of the Plains Ecoregion in 
Missouri.\72\ Therefore, EPA evaluated these waters in greater detail. 
In one instance, historical and ongoing confined animal feeding 
operations (CAFOs) in an adjacent watershed likely explained the noted 
hypereutrophic condition.\73\ The other two instances involved state-
managed fishing lakes, one situated in a formerly cultivated field and 
the other situated in a watershed extending into the heavily cultivated 
Big River Floodplain. A few other lakes on state-managed lands were 
disqualified based on disturbance related to reported sedimentation and 
algal bloom issues.\74\ EPA ultimately identified 21 reference lakes 
and reservoirs in the Plains and 27 in the Ozarks that met the criteria 
discussed above. EPA calculated seasonal geometric mean TN, TP, and 
chlorophyll a concentration values for each waterbody, then calculated 
the long-term median seasonal geometric means for each parameter/
waterbody combination. These medians were partitioned by ecoregion, 
ranked, and used in the calculation of appropriate concentration 
percentiles.\75\ EPA invites public comment on the methodology to 
select reference lakes and reservoirs for this alternative's 
methodology.
---------------------------------------------------------------------------

    \70\ Id.
    \71\ Dodds, W.K., C. Carney and R.T. Angelo. 2006. Determining 
ecoregional reference conditions for nutrients, Secchi depth and 
chlorophyll a in Kansas lakes and reservoirs. Lake and Reservoir 
Management 22(2):151-159.
    \72\ Omernik, J. M. 1987. Ecoregions of the conterminous United 
States. Annals of the Association of American Geographers 77:118-
125.
    \73\ The hog CAFO in question generated an amount of waste 
equaling a human population of about 19,000. Owing to high 
transportation costs, manure from such facilities generally is 
applied to surrounding fields and cropland.
    \74\ This is illustrated by the following excerpt from the ten-
year management plan for one of these areas: ``Strategy 1: 
Sufficient phytoplankton densities will be maintained through 
artificial fertilization to shade and discourage the development of 
rooted plant growth. Successful artificial fertilization should 
limit the need for the extensive use of grass carp or herbicides 
while increasing phytoplankton blooms and zooplankton communities 
throughout the summer and into the early fall'' (MDC. 2015. Lake 
Girardeau Conservation Area Management Plan. Missouri Department of 
Natural Resources, Southeast Region, Poplar Bluff, MO.)
    \75\ USEPA. 2000. Nutrient Criteria Technical Guidance Manual: 
Lakes and Reservoirs. EPA-822-B00-001. U.S. Environmental Protection 
Agency, Office of Water, Washington DC.
---------------------------------------------------------------------------

    To assist in the identification of appropriate concentration 
percentiles, land cover disturbance patterns in the three ecoregions 
were compared to patterns reported for the conterminous United States 
using ArcGIS. This comparison indicated that cropland and developed 
(urban) land collectively comprised 21.1 percent of the cover in the 
lower 48 states. This is comparable to the percentage reported for the 
Ozark Border (22.2 percent), higher than the percentage reported for 
the Ozark Highlands (6.9 percent), and lower than the percentage 
reported for the Plains (39.9 percent). Based on its review of the 
applicable federal guidance,\76\ EPA interpreted this to mean that 
application of the standard 75th percentile nutrient concentration 
would be appropriate for the Ozark Border, because this region has 
experienced a degree of land cover disturbance typifying that of the 
nation as a whole (excluding Alaska and Hawaii). The 75th percentile 
also was selected for the Ozark Highlands, and therefore appropriate 
for the combined Ozark ecoregion. In choosing this percentile, EPA was 
mindful of the limited number of potentially suitable reference waters 
in this region, and in turn, the difficulty in accurately estimating a 
higher percentile. EPA recognizes that there are higher levels of land 
cover disturbance in the Plains region relative to other locations in 
Missouri and most of the United States and considered using the 50th 
percentile for the Plains. However, EPA concluded that the screening 
criteria for reference sites (described above), already appropriately 
accounted for these differences by including the allowable percent of 
cropland and urban land in the lake watershed, is the same for each 
ecoregion. EPA decided to use of the 75th percentile for all 
ecoregions. EPA invites public comment on whether the use of the 75th 
percentile for these ecoregions was appropriate. EPA notes that using 
the 75th percentile of reference lakes to derive protection values 
implies that 25 percent of reference lakes would be deemed to exceed 
the protection values if assessed using the data used to derive the 
criteria. This could be interpreted to mean that 25 percent of the 
lakes meeting the reference condition selection criteria described 
above would none-the-less be determined to be impaired. This could also 
be interpreted as appropriately ensuring that high levels of nutrient 
parameters for lakes that, in fact, may or may not meet designated uses 
are not identified as protective for the vast majority of lakes that 
have much lower levels of nutrient parameters. A higher percentile 
value, such as the 90th or 95th percentile, would ensure that, at least 
based on the data used to derive the criteria, all or most of the 
reference lakes would in fact be found to meet designated uses. EPA 
invites public comment on whether the use of a higher percentile would 
be appropriate in the context of the selection criteria used by EPA to 
identify reference lakes and reservoirs for the purpose of calculating 
protective values indicative of meeting designated uses.
---------------------------------------------------------------------------

    \76\ Id.
---------------------------------------------------------------------------

    In this alternative, these concentration percentiles would serve as 
nutrient protection values as part of a combined criterion approach for 
all classified lakes and reservoirs in Missouri that (1) are listed in 
Table G of the State's WQS and the Missouri Use Designation

[[Page 61224]]

Dataset (10 CSR 20-7.031(2)(E)) with respect to use designations, (2) 
equal or exceed ten acres, (3) are located outside of the Big River 
Flood Plain Ecoregion and (4) are not already listed in Table M of the 
State's WQS. In all instances, these values are expressed as seasonal 
(April through September) geometric mean values and interpreted in the 
context of three-year rolling averages.\77\ EPA invites public comment 
on the use of moving averages versus fixed averaging periods.
---------------------------------------------------------------------------

    \77\ Use of a seasonal mean and three-year averaging period is 
consistent with recommendations set forth in: RTAG. 2011. Nutrient 
Reference Condition Identification and Ambient Water Quality 
Benchmark Development Process: Freshwater Lakes and Reservoirs 
within USEPA Region 7. Regional Technical Advisory Group, U.S. 
Environmental Protection Agency Region 7, Lenexa, KS.
---------------------------------------------------------------------------

    As described in the Technical Support Document accompanying this 
proposal, the resulting values are comparable in magnitude to those 
recommended by the Regional Technical Assistance Group (RTAG) for the 
four-state region, to criteria developed or adopted in neighboring 
Kansas, Nebraska and Oklahoma, and to TMDL targets adopted previously 
in Missouri. As such, EPA is confident that the nutrient protection 
values are protective of downstream lakes and reservoirs, though EPA 
emphasizes that this is not the only way of developing protective 
values. For protection of downstream rivers and streams, lakes often 
act as a ``sink'' for nutrients because of the relatively longer water 
residence time and associated physical processes and biochemical 
cycling. As such, lakes retain nutrients and outflow nutrient 
concentrations are generally lower than inflow nutrient concentrations. 
In terms of level of protection needed, nutrient criteria for lakes and 
reservoirs are generally lower than nutrient criteria for rivers and 
streams in the same ecoregion (see, for example, EPA's criteria 
published in 2000 for Ecoregion IX). For these reasons, EPA concludes 
that the values are protective of downstream waters and their assigned 
uses. EPA invites public comment on the derivation of EPA's proposed 
nutrient protection values based on least disturbed reference 
conditions. EPA specifically requests comments on the use of the 75th 
percentile of the reference lake values to establish the TN, TP, and 
chl-a nutrient protection values proposed for Alternative 1.

D. Proposed Combined Criterion Alternative 2

    Alternative 2 is presented in Table 4 below.

  Table 4--Alternative 2 Lake Ecoregion Chl-a Criteria, Nutrient Screening Values ([mu]g/L), and Eutrophication
                                                     Impacts
----------------------------------------------------------------------------------------------------------------
                                                                            Screening Values ([mu]g/L)
                 Lake ecoregion                   Chl-a criteria -----------------------------------------------
                                                                        TP              TN             Chl-a
----------------------------------------------------------------------------------------------------------------
Plains..........................................              30              49             843              18
Ozark Border....................................              22              40             733              13
Ozark Highland..................................              15              16             401               6
----------------------------------------------------------------------------------------------------------------
Lakes with water quality that exceed Chl-a Criteria are to be deemed impaired for excess nutrients.
Lakes with water quality that exceed screening values for Chl-a, TN, or TP are to be deemed impaired for excess
  nutrients if any of the following eutrophication impacts are documented for the respective designated uses
  within the same year. Eutrophication impacts for aquatic life uses include:
(I) Occurrence of eutrophication-related mortality or morbidity events for fish and other aquatic organisms;
(II) Epilimnetic excursions from dissolved oxygen or pH criteria;
(III) Cyanobacteria counts in excess of 100,000 cells per milliliter (cells/ml);
(IV) Observed shifts in aquatic diversity attributed to eutrophication; and
(V) Excessive levels of mineral turbidity that consistently limit algal productivity during the period May 1-
  September 30.

    As of the date of this proposal, Missouri has not finalized, and 
EPA has not made any determination with respect to, Missouri's proposed 
standards. Notwithstanding this, EPA believes it is appropriate to 
propose standards for consideration that are essentially identical to 
the proposed state standards, and is doing so in Alternative 2. 
Alternative 2 includes chl-a criteria for three ecoregions (Plains, 
Ozark Border, and Ozark Highland) that determine impairment independent 
of the screening values and eutrophication impact factors. Alternative 
2, similarly to Alternative 1, includes screening values for TN, TP, 
and chl-a (at a lower level than the criteria for chl-a) that operate 
in coordination with five eutrophication impact factors to determine 
impairment. However, as explained above, one significant distinction is 
that Alternative 1 would treat the lower chl-a screening value (called 
a ``protection value'' in Alternative 1) as stand-alone criteria and 
deem any exceedance of this value as indicative of impairment without 
assessment of additional eutrophication impacts. Alternative 2 includes 
a qualifier of ``epilimnetic'' with respect to excursion of DO or pH 
criteria to mirror the State's proposal. EPA seeks comment on limiting 
application of DO and pH criteria to the epilimnion (surface layer) of 
lakes.
    The State of Missouri has documented a supporting rationale for the 
values proposed in Alternative 2 as part of a combined criterion 
structure.\78\ This document includes maps of the three ecoregions 
(Plains, Ozark Border, and Ozark Highland). In this document, Missouri 
describes how it considered input from a stakeholder group and 
``decided on an approach that provided for the most scientifically 
defensible protections for the underlying designated uses.'' Missouri 
indicates that its approach ``focuses on the biological response, 
considers ecoregional differences and existing trophic levels, and 
supplements criteria with conservative screening values coupled with 
weight of evidence analysis to better support determinations of 
impairment''. Missouri indicates that it reviewed several different 
sources of information to derive reservoir numeric nutrient criteria, 
including recent numeric nutrient criteria development activities in 
other states, Missouri-specific reservoir water chemistry data, 
literature reviews, and expert opinion.
---------------------------------------------------------------------------

    \78\ Missouri Department of Natural Resources. 2016. Missouri 
Lake Numeric Nutrient Criteria Rationale of Nov. 21, 2016.
---------------------------------------------------------------------------

    Missouri indicated the stand-alone independent chl-a criterion for 
the Plains ``is conservatively set to support sport fisheries rather 
than maximizing

[[Page 61225]]

sport fish harvest. Missouri maintains that using sport fishery status 
as an indicator of aquatic life use protection is ecologically 
justified because sport fish are generally apex predators in reservoir 
systems. Therefore, the health of sport fish populations can be 
interpreted as an indicator of overall ecosystem health and the 
presence a `wide variety' of aquatic biota, as defined in the existing 
regulations''.\79\ For the Ozark Highlands, Missouri identified ``a 
lower chlorophyll concentration of 15 [mu]g/L, which reflects the 
regional pattern of reservoir fertility associated with the different 
physiographic regions of the state''.\80\ Because the Ozark Border 
section represents a transition zone between the Plains and Ozark 
Highlands, Missouri identified a chl-a criterion intermediate to the 
other two sections. Missouri proposed chl-a screening values equal to 
the 50th percentile of the distribution of growing season chlorophyll 
data for each ecoregion, and back calculated TN and TP screening values 
using regression relationships with chl-a presented in their rationale 
document.
---------------------------------------------------------------------------

    \79\ Id.
    \80\ Id.
---------------------------------------------------------------------------

    EPA is seeking comment on whether the chl-a criteria in Alternative 
2 would protect the State's designated uses for these lakes. EPA seeks 
comment on whether a different (i.e., more protective) level of chl-a 
as a eutrophication impact factor is necessary to protect the 
designated uses for these lakes. EPA further seeks comment on whether 
or not the hypothetical scenario pursuant to Alternative 2 is 
scientifically supportable as protecting the designated use: Not 
identifying a lake as impaired when it (1) exceeds a screening value 
for TP or TN, (2) exceeds a screening value for chl-a, and (3) there 
are no documented eutrophication impacts. In other words, EPA seeks 
comment on whether it is sufficient or insufficient to identify 
impairment if a water body exceeds a screening value for TN or TP and 
also exceeds a screening value for chl-a.
    The combined criterion could function in the manner proposed for 
Alternative 1, where a lake with water quality that exceeds protection 
values for TN or TP is deemed impaired for excess nutrients unless each 
of the eutrophication impacts are evaluated and none occur within the 
same evaluation period (or unless the chl-a protection value is 
exceeded). In contrast, the combined criterion could function in the 
manner proposed for Alternative 2, where a lake with water quality that 
exceeds a screening value for TN, TP, or chl-a (at a ``screening'' 
level) is deemed impaired for excess nutrients only if one or more of 
the eutrophication impacts are documented to occur within the same 
year. Using this Alternate 2 expression, a lake exceeding screening 
values for TN, TP, or chl-a (at a ``screening'' level) would not be 
considered to be impaired unless and until additional information is 
collected and evaluated to confirm the impairment. EPA has not 
separately prepared supporting documentation for Alternative 2 at the 
same level of detail as for Alternative 1, because as noted above, 
Alternative 2 is intended to closely mirror the State's 2017 proposed 
rule. Accordingly, EPA has placed documentation as provided by the 
State, in its own docket as an integral part of the supporting 
documentation for Alternative 2. EPA is asking for comment on this 
approach.
    EPA also has not provided proposed regulatory text for Alternative 
2, because the regulatory text for this option would be largely 
identical to the regulatory text in the State's 2017 proposed rule. 
Rather, the Agency is providing notice of its consideration of 
Alternative 2 in the preamble to today's proposed rule. The Agency 
recognizes that, if the Agency were to adopt this alternative in the 
final rule, there may need to be formatting changes to the State 
regulatory text to conform to requirements applicable to codification 
in the Code of Federal Regulations.

E. Additional Alternative Approaches Considered

    This federal action fulfills EPA's commitment under the consent 
decree with MCE to propose criteria addressing its 2011 disapproval by 
December 15, 2017. EPA acknowledges that the alternatives in the 
current proposal are not the only possible options that EPA could 
promulgate or Missouri could adopt to address the 2011 disapproval 
action. When promulgating federal water quality standards for a state, 
EPA's preference is to rely on state-specific data, where available, to 
derive criteria to protect the state's applicable designated uses. EPA 
solicits comment from the public and stakeholders on the Agency's co-
proposals, in addition to other scientifically defensible options, to 
support a well-informed and robust final rule that reflects thoughtful 
consideration of Missouri's regulatory structure and implementation 
mechanisms.
    EPA considered several alternatives to the two alternatives 
proposed combined criterion approaches, component nutrient protection 
(or screening) values, and eutrophication impacts, and is interested in 
public comment on these approaches. First, EPA considered proposing the 
reference condition-derived nutrient protection values as stand-alone 
nutrient criteria (i.e., in absence of a combined criterion structure). 
However, given Missouri's interest in the combined criterion approach 
and EPA's position that such an approach can be appropriate and 
protective, EPA elected to structure the two alternatives in this 
proposal in a similar fashion. Second, EPA considered relying on fewer 
response parameters to avoid use of factors that may be onerous to 
routinely measure and assess, may be subject to various 
interpretations, and may not be necessary to indicate adverse impact. 
For example, EPA considered using only chl-a, DO, and pH as 
eutrophication impacts. EPA instead elected to include the full set 
Missouri identified in recognition that Missouri had concluded each was 
an appropriate eutrophication impact to be included in the State's 
proposed rule. Lastly, for Alternative 1, EPA considered using the 50th 
percentile of the data from reference lakes in the Plains ecoregion for 
deriving nutrient protection values; these values are 9.8 [micro]g/L 
chl-a, 39 [micro]g/L TP, and 690 [micro]g/L TN. EPA decided to use the 
75th percentile for the Plains ecoregion for this proposal because 
reference lakes in both ecoregions could have no greater than 20 
percent cropland and urban land in their watershed based on EPA's 
screening procedure. EPA specifically solicits comment on the use of 
the 50th percentile for the Plains. As noted above, EPA is also 
requesting comment on using a higher percentile, such as 90th or 95th.

F. Applicability of Combined Criterion When Final

    Unless EPA approves water quality standards addressing EPA's 2011 
disapproval, EPA's proposed nutrient combined criterion for Missouri's 
lakes and reservoirs would be effective for CWA purposes 60 days after 
publication of a final rule. The proposed combined criterion in this 
rule, if finalized would be subject to Missouri's general rules of 
applicability in the same way and to the same extent as are other 
state-adopted criteria.
    EPA's proposed nutrient combined criterion, if finalized, would 
serve as a basis for development of new or revised National Pollutant 
Discharge Elimination System (NPDES) permit limits in Missouri for 
regulated dischargers found to have reasonable potential to cause or 
contribute to an

[[Page 61226]]

excursion of the proposed nutrient combined criterion. Although EPA 
cannot be certain of whether a particular direct or indirect discharger 
would change their operations if these proposed criterion were 
finalized, EPA acknowledges that point source dischargers would need to 
be assessed to determine if they have a reasonable potential for the 
discharge to cause or contribute to an excursion of the water quality 
standard, and could well be subject to additional water quality-based 
effluent limits as a result. Nonpoint dischargers could also be subject 
to additional control requirements under Missouri law, perhaps in 
conjunction with a TMDL. Missouri has NPDES permitting authority, and 
retains discretion in issuing permits consistent with CWA permitting 
regulations, which require that permit limits be established such that 
permitted sources do not cause or contribute to a violation of water 
quality standards, including numeric nutrient criteria.

IV. Tributary Arms

    As part of its efforts to establish its water quality standards, 
the State of Missouri established water quality criteria in its 2009 
WQS submission to address nutrient-related pollutants for certain 
lakes, reservoirs and tributary arms. As mentioned previously, on 
August 16, 2011, EPA disapproved most numeric criteria for TN, TP, and 
chl-a for Missouri lakes and reservoirs and also disapproved TP 
criteria for tributary arms Grand Glaize, Gravois, and Nianga to the 
Lake of the Ozarks, and tributary arms James River, Kings River, and 
Long Creek to Table Rock Lake. In Missouri's disapproved rule (10 CSR 
20-7.0314)(N)(1)(D)) and current proposed rule (10 CSR 20-
7.031(N)(1)(E)), it considers a tributary arm to be a substantial 
segment of a Class L2 lake that is primarily recharged by a source or 
sources other than the main channel of the lake. EPA requests public 
comments on applying Alternative 1, Alternative 2, or any other 
appropriate alternative to the respective tributary arms to address 
EPA's 2009 disapproval. EPA invites the public to provide any data or 
scientific information to inform decision-making towards this option.

V. Endangered Species Act

    Section 7(a)(2) of the Endangered Species Act (ESA) requires the 
EPA, in consultation with the U.S. Fish and Wildlife Service (USFWS) 
and/or the National Marine Fisheries Service (NMFS), to ensure that any 
action authorized by the Agency is not likely to jeopardize the 
continued existence of any endangered or threatened species or result 
in the destruction or adverse modification of designated critical 
habitat for such species.
    Pursuant to this section, EPA intends to initiate consultation with 
USFWS regarding the effects that finalizing this rulemaking would have 
on federally-listed threatened and endangered species and designated 
critical habitat. EPA will subsequently conduct a biological evaluation 
to determine whether any federally-listed threatened or endangered 
species or their critical habitat are likely to be adversely affected 
by the finalization of this rulemaking.

VI. Under what conditions will federal standards be either not 
finalized or withdrawn?

    Under the CWA, Congress gave states primary responsibility for 
developing and adopting WQS for their navigable waters. See CWA section 
303(a)-(c). Although EPA is proposing nutrient criteria for Missouri's 
lakes and reservoirs, the State has the option of adopting and 
submitting revised nutrient criteria for these waters consistent with 
CWA section 303(c) and implementing regulations at 40 CFR part 131. 
Consistent with CWA section 303(c)(4) and the consent decree discussed 
in Section II, if Missouri adopts water quality criteria to address 
EPA's 2011 disapproval, and if EPA approves such criteria prior to the 
December 15, 2018 consent decree deadline to publish the final rule, 
EPA will not proceed with the final rulemaking.
    Pursuant to 40 CFR 131.21(c), if EPA does promulgate final 
criteria, they would be applicable for the purposes of the CWA. EPA 
could eventually withdraw any federally promulgated criteria through a 
rulemaking. EPA would undertake a withdrawal action if Missouri adopts 
and EPA approves water quality criteria to address EPA's 2011 
disapproval as meeting CWA requirements.

VII. WQS Regulatory Approaches and Implementation Mechanisms

    The Federal water quality standards regulation at 40 CFR part 131 
provides several tools that Missouri has available to use at its 
discretion when implementing or deciding how to implement these numeric 
nutrient criteria, if finalized. Among other things, EPA's WQS 
regulation: (1) Specifies how states and authorized tribes establish, 
modify or remove designated uses, (2) specifies the requirements for 
establishing criteria to protect designated uses, including criteria 
modified to reflect site-specific conditions, (3) authorizes and 
provides requirements for states and authorized tribes to adopt WQS 
variances that provide time to achieve the underlying WQS, and (4) 
allows states and authorized tribes to authorize the use of compliance 
schedules in NPDES permits to meet Water Quality Based Effluent Limits 
(WQBELs) derived from the applicable criteria. Each of these approaches 
is discussed in more detail in the next sections.

A. Designating Uses

    Federal regulations at 40 CFR 131.10 provide regulatory 
requirements for establishing, modifying, and removing designated uses. 
If Missouri removes or modifies the aquatic life or recreational 
designated uses of a lake or reservoir subject to EPA's proposed 
nutrient criteria and adopts the highest attainable use,\81\ the state 
must also adopt criteria to protect the newly designated highest 
attainable use consistent with 40 CFR 131.11. Any designated use change 
must meet the requirements of 40 CFR part 131 and obtain EPA approval. 
If EPA finds removal or modification of the designated use, the 
adoption of the highest attainable use and criteria to protect that use 
is consistent with CWA section 303(c) and the implementing regulation 
at 40 CFR part 131 and thus approves the revised WQS, then the new or 
revised use and criteria would become effective for CWA purposes. As an 
additional step, EPA would initiate rulemaking to withdraw its 
promulgation of nutrient criteria in Missouri if the criteria to 
protect the new use is something other than the federally promulgated 
criteria.
---------------------------------------------------------------------------

    \81\ If a state or authorized tribe adopts a new or revised WQS 
based on a required use attainability analysis, then it must also 
adopt the highest attainable use (40 CFR 131.10(g)). Highest 
attainable use is the modified aquatic life, wildlife, or 
recreational use that is both closest to the uses specified in 
section 101(a)(2) of the Act and attainable, based on the evaluation 
of the factor(s) in 40 CFR 131.10(g) that preclude(s) attainment of 
the use and any other information or analyses that were used to 
evaluate attainability. There is no required highest attainable use 
where the state demonstrates the relevant use specified in section 
101(a)(2) of the Act and sub-categories of such a use are not 
attainable (See 40 CFR 131.3(m)).
---------------------------------------------------------------------------

B. Site-Specific Criteria

    The regulation at 40 CFR 131.11 specifies requirements for 
modifying water quality criteria to reflect site-specific conditions. 
In the context of this rulemaking, a site-specific criterion (SSC) is 
an alternative to a federally promulgated nutrient criterion that would 
be applied on a watershed, area-wide, or water body-specific basis,

[[Page 61227]]

provided this alternative is protective of the designated use, is 
scientifically defensible, and provides for the protection and 
maintenance of downstream water quality. A SSC may be more or less 
stringent than the otherwise applicable federal criterion. A SSC may be 
appropriate when further scientific data and analyses more precisely 
define the concentration of a pollutant that is protective of the 
designated uses of a particular watershed, region, or water body. If 
Missouri adopts, and EPA approves, a SSC that fully meets the 
requirements of both section 303(c) of the CWA and EPA's implementing 
regulation at 40 CFR part 131, EPA would undertake a rulemaking to 
withdraw the corresponding federal criterion for the water(s) affected 
by the SSC.

C. WQS Variances

    Federal regulations at 40 CFR 131.14 define a WQS variance as a 
time-limited designated use and criterion, for a specific pollutant or 
water quality parameter, that reflects the highest attainable condition 
during the term of the WQS variance. WQS variances adopted in 
accordance with 40 CFR 131.14 (including a public hearing consistent 
with 40 CFR 25.5) provide a flexible but defined pathway for states and 
authorized tribes to meet their NPDES permit obligations by allowing 
dischargers the time they need (as demonstrated by the state or 
authorized tribe) to make incremental progress toward meeting WQS that 
are not immediately attainable but may be in the future. When adopting 
a WQS variance, states and authorized tribes specify the interim 
requirements of the variance by identifying a quantitative expression 
that reflects the highest attainable condition (HAC) during the term of 
the variance, defining the term of the variance, and describing the 
pollutant control activities to achieve the HAC during the term of the 
variance. WQS variances will help states and authorized tribes focus on 
improving water quality, rather than pursuing a downgrade of the 
underlying water quality goals through modification or removal of a 
designated use, as a variance cannot lower currently attained water 
quality. As water quality standards, variances are submitted to EPA for 
review and approval under CWA section 303(c) which provides legal 
avenue by which NPDES permit limits can be written to derive from, and 
comply with, the WQS variance rather than the underlying WQS, for the 
term of the WQS variance. If dischargers are still unable to meet the 
WQBELs derived from the applicable WQS once a variance term is 
complete, the regulation allows the state to adopt a subsequent 
variance if it is adopted consistent with 131.14.
    EPA's proposed nutrient criterion applies to use designations that 
Missouri has already established. Missouri may adopt time-limited 
designated uses and criteria to apply for the purposes specified in 40 
CFR 131.14(a)(3).

D. NPDES Permit Compliance Schedules

    EPA's regulations at 40 CFR 122.47 and 40 CFR 131.15 address how 
states and authorized tribes include permit compliance schedules in 
their NPDES permits if dischargers need additional time to meet their 
WQBELs based on the applicable WQS. EPA's updated regulations at 40 CFR 
131.15 require that states and authorized tribes that wish to allow the 
use of permit compliance schedules adopt specific provisions 
authorizing their use and obtain EPA approval under CWA section 303(c) 
to ensure that a decision to allow permit compliance schedules is 
transparent and allows for public input (80 FR 51022, August 21, 2015). 
On December 11, 2012, Missouri submitted a revised compliance schedule 
authorizing provision at 10 CSR 20-7.031(10). This revision was partly 
approved by EPA on January 25, 2015. Missouri is authorized to grant 
permit compliance schedules, as appropriate, to permitted facilities 
impacted by federally promulgated numeric nutrient criteria as long as 
such compliance schedules are consistent with EPA's permitting 
regulation at 40 CFR 122.47.

VIII. Economic Analysis

    At this time, EPA has prepared only a preliminary economic analysis 
specifically for Alternative 1. This analysis will be further refined 
and an updated more comprehensive economic review will be put out for 
comment in a Notice of Data Availability at a later time. At that time, 
to best inform the public of the potential impacts of this rule, EPA 
will evaluate the potential benefits and costs associated with 
implementation of EPA's proposed criterion.
    The analysis of acres with BMPs to address nonpoint sources of 
nutrients was conducted at the HUC-12 level of resolution. Many of the 
potentially incrementally impaired lakes in Missouri are small, and 
their watersheds are smaller than the HUC-12 watershed in which they 
are located; thus, the estimated costs for these watersheds may be 
overstated. However, EPA did not initially include any costs for 
watersheds for which it does not have data, thus, at least some likely 
costs were not included in the preliminary analysis. Due to these and 
other limitations, EPA believes that its current draft analysis is too 
preliminary to adequately inform public comment on the rule. EPA will 
address these issues in the updated analysis provided in the NODA.
    EPA also preliminarily estimated the benefits from water quality 
improvements resulting from implementing the nutrient protection values 
in Missouri Lakes and reservoirs. However, due to data and resource 
limitations and other challenges, EPA believes that this benefits 
analysis is also too preliminary to be presented at this time. EPA will 
also include an updated analysis of benefits in the NODA.
    EPA seeks public comment to inform EPA's economic analysis. EPA is 
interested in public comment regarding how likely it is that lakes 
without water quality data may trigger the screening criteria; what 
practices the agricultural sector and cities may take to reduce 
nonpoint source discharges and the likelihood that such practices are 
implemented; what unit costs EPA should consider using in conducting 
this analysis; and what assumptions EPA should consider using for 
expected nutrient load reductions.
    EPA intends to make the revised analysis, including pre-publication 
peer review, available for public comment no later than six months 
after the date of publication of this proposed rule. In no 
circumstances will EPA issue a final rule without providing an economic 
analysis sufficiently in advance of the final rule for public comment 
on the analysis to meaningfully inform EPA's development of the rule.

IX. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action is an economically significant regulatory action that 
was submitted to the Office of Management and Budget (OMB) for review. 
Any changes made in response to OMB recommendations have been 
documented in the docket. (Docket Id. No. EPA-HQ-OW-2009-0596) is 
available in the docket. A summary of the report can be found in 
Section VIII of this preamble.

[[Page 61228]]

B. Executive Order 13771: Reducing Regulation and Controlling 
Regulatory Costs

    This action is expected to be an Executive Order 13771 regulatory 
action. Details on the estimated costs of this proposed rule will be 
available for public comment in a subsequent Notice of Data 
Availability to be published no later than six months after this 
proposed rule (See summary at Section VIII. Economic Analysis, and full 
economic analysis report in the docket for this proposed rulemaking).

C. Paperwork Reduction Act

    This action does not impose an information collection burden under 
the provisions of the PRA, 44 U.S.C. 3501 et seq. Burden is defined at 
5 CFR 1320.3(b). This action does not include any information 
collection, reporting, or record-keeping requirements.

D. Regulatory Flexibility Act

    For purposes of assessing the impacts of this action on small 
entities, a small entity is defined as: (1) A small business as defined 
by the Small Business Administration's (SBA) regulations at 13 CFR 
121.201; (2) a small governmental jurisdiction that is a government of 
a city, county, town, school district or special district with a 
population of less than 50,000; and (3) a small organization that is 
any not-for-profit enterprise that is independently owned and operated 
and is not dominant in its field.
    Under the CWA, states must adopt WQS for their waters and submit 
these standards to EPA for approval. If the Agency disapproves a 
submitted standard and the state does not adopt revisions to address 
EPA's disapproval, EPA must promulgate standards consistent with the 
CWA requirements. State standards (or EPA-promulgated standards) are 
implemented through various water quality control programs including 
the NPDES program, which limits discharges to navigable waters except 
in compliance with an NPDES permit. The CWA requires that all NPDES 
permits include any limits on discharges that are necessary to meet 
applicable WQS. Thus, under the CWA, EPA's promulgation of WQS 
establishes standards that the state implements through the NPDES 
permit process. The State has discretion in developing discharge 
limits, as needed to meet the standards. This proposed rule, as 
explained earlier, does not itself establish any requirements that are 
applicable to small entities. As a result of this action, the State of 
Missouri will need to ensure that permits it issues include any 
limitations on discharges necessary to comply with the standards 
established in the final rule. In doing so, the state will have a 
number of choices associated with permit writing. While Missouri's 
implementation of the rule may ultimately result in new or revised 
permit conditions for some dischargers, including small entities, EPA's 
action, by itself, does not impose any of these requirements on small 
entities; that is, these requirements are not self-implementing. Thus, 
I certify that this rule will not have a significant economic impact on 
a substantial number of small entities under the RFA.

E. Unfunded Mandates Reform Act

    This proposed rule contains no federal mandates (under the 
regulatory provisions of Title II of the UMRA) for state, local, or 
tribal governments or the private sector.
    EPA determined that this proposed rule contains no regulatory 
requirements that might significantly or uniquely affect small 
governments. Moreover, WQS, including those proposed here, apply 
broadly to dischargers and are not uniquely applicable to small 
governments. Thus, this proposed rule is not subject to the 
requirements of section 203 of UMRA.

F. Executive Order 13132 (Federalism)

    This action does not have federalism implications as that term is 
used in EO 13132. Although section 6 of Executive Order 13132 does not 
apply to this action, EPA had extensive communication with the State of 
Missouri to discuss EPA's concerns with the State's previously 
submitted and disapproved criteria and the federal rulemaking process. 
In the spirit of Executive Order 13132, and consistent with EPA's 
policy to promote communications between EPA and state and local 
governments, EPA specifically solicits comment on this proposed rule 
from state and local officials.

G. Executive Order 13175 (Consultation and Coordination With Indian 
Tribal Governments)

    This action does not have any tribal implications as specified by 
Executive Order 13175. As there are no federally-recognized tribes in 
the State of Missouri, this executive order does not apply. Thus, 
Executive Order 13175 does not apply to this action.

H. Executive Order 13045 (Protection of Children from Environmental 
Health and Safety Risk)

    Executive Order 13045 (62 FR 19885, April 23, 1997) requires 
agencies to identify and assess health and safety risks that may 
disproportionately affect children and ensure that activities address 
disproportionate risks to children. This action not subject to 
Executive Order 13045 because the EPA does not believe the 
environmental health risks or safety risks addressed by this action 
present a disproportionate risk to children.

I. Executive Order 13211 (Actions That Significantly Affect Energy 
Supply, Distribution, or Use)

    This rule is not a ``significant energy action'' because it is not 
likely to have a significant adverse effect on the supply, 
distribution, or use of energy.

J. National Technology Transfer Advancement Act of 1995

    EPA is not aware of any voluntary consensus standards that address 
the numeric nutrient criteria in this proposed rule.

K. Executive Order 12898 (Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations)

    EPA has determined that this proposed rule does not have 
disproportionately high and adverse human health or environmental 
effects on minority or low-income populations because it would afford a 
greater level of protection to both human health and the environment if 
these nutrient criteria are promulgated in the State of Missouri.

List of Subjects in 40 CFR Part 131

    Environmental protection, water quality standards, nutrients, 
Missouri.

    Dated: December 15, 2017.
E. Scott Pruitt,
Administrator.

    For the reasons set out in the preamble, EPA proposes to amend 40 
CFR part 131 as follows:

PART 131--WATER QUALITY STANDARDS

0
1. The authority citation for part 131 continues to read as follows:

    Authority:  33 U.S.C. 1251 et seq.

Subpart D--[Amended]

0
2. Section 131.47 is added as follows:

Sec.  131.47  Missouri.

    (a) Scope. This section promulgates a combined criterion for 
designated uses for all lakes and reservoirs in the State of Missouri 
that (1) are listed in Table G and the Missouri Use Designation 
Dataset) in the State's water quality standards (WQS) (10 CSR 20-
7.031), (2)

[[Page 61229]]

equal or exceed ten acres, (3) are located outside of the Big River 
Flood Plain Ecoregion and (4) are not listed as having site-specific 
criteria in Table M of the State's WQS.
    (b) Combined Criterion for Missouri lakes and reservoirs. In all 
instances, nutrient protection values are maximum ambient 
concentrations expressed as seasonal (April through September) 
geometric mean values on a three-year rolling average basis.

          Table 1--Lake Ecoregion Nutrient Protection Values ([micro]g/L) and Eutrophication Impacts *
----------------------------------------------------------------------------------------------------------------
                         Lake Ecoregion                                 TP              TN             Chl-a
----------------------------------------------------------------------------------------------------------------
Plains..........................................................              44             817              14
Ozarks..........................................................              23             500             7.1
----------------------------------------------------------------------------------------------------------------
* Table 1 also applies to tributary arms Grand Glaize, Gravois, and Nianga to the Lake of the Ozarks, and
  tributary arms James River, Kings River, and Long Creek to Table Rock Lake.

    (1) Lake and reservoir water quality must not exceed nutrient 
protection values for chlorophyll a.
    (2) Lake and reservoir water quality must also not exceed nutrient 
protection values for total nitrogen and total phosphorus unless each 
of the following eutrophication impacts are evaluated and none occur 
within the same three-year rolling average period: (I) Eutrophication-
related mortality or morbidity events for fish and other aquatic 
organisms, (II) An excursion from the DO or pH criteria in Missouri 
water quality standards applicable for Clean Water Act purposes, (III) 
Cyanobacteria counts equal to or greater than 100,000 cells per ml, 
(IV) Observed shifts in aquatic diversity directly attributable to 
eutrophication, or (V) Excessive levels of mineral turbidity that 
consistently limit algal productivity during the period May 1--
September 30, or Secchi disk measurements of turbidity equal to or less 
than EPA's recommended Level III Ecoregions IX (1.53 m) or IX (2.86 m).
(c) Applicability
    (1) The combined criterion in paragraph (b) of this section applies 
to waters discussed in paragraph (a) of this section and applies 
concurrently with other applicable water quality criteria.
    (2) The combined criterion established in this section is subject 
to Missouri's general rules of applicability in the same way and to the 
same extent as state-adopted and EPA-approved water quality criteria 
when applied to the waters discussed in paragraph (a).
    (d) Effective date. Section 131.47 will be in effect [date 60 days 
after publication of final rule].

[FR Doc. 2017-27621 Filed 12-26-17; 8:45 am]
 BILLING CODE 6560-50-P