MRC Comments: CWA 304(a) Ambient Water Quality Criteria

This document constitutes the comments of Mississippi River Collaborative and Environmental Law & Policy Center of the Midwest regarding the Frequently Asked Questions: Implementing the 2021 Recommended Clean Water Act 304(a) Ambient Water Quality Criteria to Address Nutrient Pollution in Lakes and Reservoirs (January 2023)

The Mississippi River Collaborative is a partnership of environmental organizations and legal centers from states bordering the Mississippi River as well as regional and national groups working on issues affecting the Mississippi River and its tributaries. The Collaborative harnesses the resources and expertise of its diverse organizations to reduce pollution entering the Mississippi River as well as the Gulf of Mexico.

The Environmental Law & Policy Center of the Midwest is public interest environmental legal advocacy organization dedicated to improving environmental quality and protecting our natural resources. Among other issues, ELPC has a robust program to protect lakes and reservoirs from the dangers of toxic algal growth.

General Comments

We are pleased that EPA is taking further steps to assist states in developing numeric nutrient criteria. This is particularly true given that at least one state in the Mississippi River basin has even stated that it cannot establish numeric limits in NPDES permits in the absence of numeric standards or completion of a TMDL. See, Response to comments on the draft NPDES permit for the City of Franklin, the Tennessee Department of Environment and Conservation, (Feb. 1, 2023) at pdf pp.72, 84 (attached) Many other states have acted the same way while being less open about their violation of 40 CFR 122.44(d).

Accordingly, we must emphasize that the Guidance should make clear that:

1. States should act to establish numeric nutrient (nitrogen, N and phosphorus, P) criteria as soon as possible to expedite the NPDES permit writing process.

As stated in the March 16, 2011 Memo by then Acting Assistant Administrator Nancy K. Stoner, “[i]t has long been EPA’s position that numeric nutrient criteria targeted at different categories of water bodies and informed by scientific understanding of the relationship between nutrient loadings and water quality impairment are ultimately necessary for effective state programs.”

2. State NPDES permit writers must establish numeric N and P limits in NPDES permits to prevent violation of narrative standards, as required by 40 CFR 122.44(d).

As explained in American Paper Inst. v. United States EPA, 996 F.2d 346, 350 (D.C. Cir. 1993), 40 C.F.R. § 122.44(d)(1)(vi) was enacted to address what permit writers should do to protect against violations of narrative standards.

On its face, section 301 [of the Clean Water Act] imposes this strict requirement as to all standards—i.e., permits must incorporate limitations necessary to meet standards that rely on narrative criteria to protect a designated use as well as standards that contain specific numeric criteria for particular chemicals. The distinctive nature of each kind of criteria, however, inevitably leads to significant distinctions in how the two types of criteria are applied to derive effluent limitations in individual permits. When the standard includes numeric criteria, the process is fairly straightforward: the permit merely adopts a limitation on a point source’s effluent discharge necessary to keep the concentration of a pollutant in a waterway at or below the numeric benchmark. Narrative criteria, however, present more difficult problems: How is a state or federal NPDES permit writer to divine what limitations on effluent discharges are necessary to assure that the waterway contains, for example, “no toxics in toxic amounts”?

This difficulty does not allow permit writers to “throw up their hands”; instead, they must use one or more of the “yardsticks” provided by 40 C.F.R. § 122.44(d)(1)(vi) to write numeric limits. 996 F.2d at 350, see also, Prairie Rivers Network v. Ill. Pollution Control Bd., 2016 IL App (1st) 150971.

3. If states do not use the EPA 304(a) Lake and Reservoir Criteria Document, they must determine another method to protect aquatic life and recreation uses.

40 CFR 122.44(d) spells out how states are to set permit limits in the absence of numeric criteria. See also, Upper Blackstone Water Pollution Abatement Dist. v. U.S. Envtl. Prot. Agency, 690 F.ed 9, 21-­‐28 (1st Cir. 2012)

4. EPA’s Section 304(a) criteria are not sufficient to protect certain uses.

Finally, we must reemphasize that to protect human health, recreation, and aquatic life adequately, EPA will ultimately have to impose far more stringent nutrient standards. Indeed, for sensitive beneficial species, existing science does not support allowing a level of nutrient pollution significantly above background levels that can be called “safe.” While human-­‐related increases in nutrient levels can improve bass fishing up to a point in some waterbodies, such increases have adverse consequences on sensitive species indigenous to the waterbody. Accordingly, as discussed below, the existing criteria, U.S. EPA (2000), based on the levels of N and P in minimally polluted (i.e., minimally impacted or “reference”) waterbodies, should be maintained for protection of aquatic life and EPA must assure that the federal antidegradation policy is rigorously implemented. (Our earlier comments are re-submitted with this comment.)

Section by Section Comments

Given our disagreement with some of the underlying criteria, it is not in some cases reasonable for us to comment on whether the FAQ properly explains the criteria. As to many answers, we have no comment.

1.11 For the reasons given in our earlier comments, the criteria are inadequate to protect aquatic life, recreation and drinking water fully. For example, we are not convinced that the criteria protect against cyanotoxins other than microcystins, or protect recreation uses other than swimming. Further, we believe that states should continue to consider data based on the reference condition approach because it does not appear that waters can receive any significant level of nutrient pollution without suffering some level of impairment such as loss of sensitive beneficial species.

1.2 It should also be noted that, while the growing season is the period for many harmful algal bloom (HAB) species, other species can from blooms in winter, sometimes even under ice. States and tribes may use the suggested approaches as one tool to meet narrative criteria, but criteria selected using these approaches are inadequate to protect against many forms of unnatural plant and algal growth stimulated by N and P pollution.

1.3 We believe that states should adopt causal N and P criteria and response criteria including pH, dissolved oxygen (greater than 120% saturation, diel variation, and minima), and aesthetic considerations for the waterbody.

1.5 States should have criteria for at least total nitrogen (TN), nitrate+nitrite, total ammonia (ionized + unionized, tNH3), and total phosphorus (TP). Unfortunately, most states do not have criteria for TN, have only the inadequate 10 mg/L drinking water standard for nitrate (if that), old ammonia standards and, outside part of the Great Lakes basin, no P standards.

1.7  States should at a minimum apply some DO criteria to every portion of a lake or reservoir that has aquatic life requiring oxygen, with minimum levels necessary to support the aquatic life that could live in that area of the lake were it not polluted.

1.18 Given that data were not available for cyanotoxins other than microcystins, prudence requires that N and P criteria be applied so as to allow a margin of safety. Eventually getting down to reference (minimally impacted) levels of N and P pollutants should be set forth as the goal.

1.19 The “highest attainable use” and reference (minimally impacted) level of N and P pollution should be achieved to the extent that the discharger (with federal and state assistance in some cases) can do so without suffering “substantial and widespread economic impact.” 40 CFR 131.10(g)

2.1 It is useful to collect these resources.

2.2 We agree that it is not necessary generally to limit chlorophyll a for the reason given. However, permit writers should place limits on temperature (heat) and chloride with the understanding that those pollutants tend to aggravate the impact of nutrient pollution and favor cyanobacteria.

2.3 This is useful but it should be stressed that reasonable potential must be determined as to both numeric and narrative criteria, and limits should be placed in the permit whenever reasonable potential is found.

2.4 While averaging periods may be different for some forms of nutrient pollution than for toxins, two points need to be considered. First, some nutrient forms, specifically ammonia, nitrate, and nitrite, can act as toxins. Second, the criteria should reflect the fact that summer, when flows are frequently low and temperatures high, is the season when blooms of many harmful algal species are most likely and when people are most likely to be in the water. Moreover, maximal summer temperature/low flow conditions need to be considered. The fish and other aquatic life do not have to survive on the basis of an annual average; they have to survive daily extremes.

2.5 This section is helpful, but it should be made clear that increased pollution can never be allowed into a waterbody that is already impaired for the pollutant at issue. Dilution is never the solution to pollution when there is no dilution capacity available.

2.6 The CWA Section 304(a) criteria should be used to set a maximum level of N and P that may be tolerated, but the 2021 Lake Criteria were not designed to address toxins other than microcystins and do not directly address aesthetic or some recreation uses of lakes. Anyone who has attempted to paddle through waves of Eurasian watermilfoil or various other invasive plants can testify that such aquatic plants can greatly impair recreation uses, and some invasive plant species are known to thrive in P-­‐ polluted conditions.

2.7 Trading schemes must not create areas of impairment and must result in fully enforceable permits and loading levels.

2.8 The FAQ quite properly mentions that financial assistance may be available in many cases. The listing of sources is very helpful. Variances should not be granted on the basis of economic impact unless all possible sources of financial assistance to meet WQBELs have been considered.

2.9 This listing of tools with connections to the sources is very helpful.

3.1 Chlorophyll monitoring (corrected for pheopigments) from May to September is clearly necessary. However, in some cases we have observed extreme oxygen supersaturation that could only have been caused by eutrophication as early as February, even in northern Illinois. Thus, some monitoring in other seasons is also necessary.

3.2 States and tribes, to the extent feasible, should also assess waters using pH (greater than 8.3), DO supersaturation (greater than 120%), minimum DO, and diel DO variation (greater than 3.5 mg/L) as also indicating eutrophication.

3.5 The 2021 304(a) criteria should not be used in any case to loosen P criteria because the database used to develop the 2021 criteria does not include the Great Lakes. Certain other state criteria (recently updated using a broad range of biological and aesthetic data) also should be retained.

3.6 Listings based on DO, pH or higher plant (macrophyte) abundance data should not be removed on the basis that the water bodies are meeting the 2021 Lake criteria.

3.7 Waters that were listed because of excessive plant growth, green algae or cyanotoxins other than microcystins should not be de-­‐listed based on the 2021 criteria.

3.11 We are concerned that the amount of sampling recommended by EPA does not reflect the variability of P and N levels, particularly for lakes and reservoirs in agricultural and urban areas. A single sample of 12 µg/L TP does not capture P levels during periods of low flow and high temperatures when HABs are most likely.

4.2 We strongly support this answer and the need for protection of drinking source water.

4.3 It is very dangerous to allow toxic levels of microcystins by depending on a “technofix” -­‐-­‐ that is, based on the hope that the drinking water treatment plant will correct the problem.

We appreciate this chance to share our comments on the EPA Draft and would be happy to answer any questions. We look forward to continuing to work with U.S. EPA to protect water quality from nutrient pollution and other forms of pollution.


Albert Ettinger, Counsel to Mississippi River Collaborative


Robert Michaels, Senior Attorney, Environmental Law & Policy Center of the Midwest

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