                                STATE OF MINNESOTA
                                IN COURT OF APPEALS
                                      A16-0854

                      Minnesota Center for Environmental Advocacy,
                                         Relator,

                                             vs.

                                      City of Winsted,
                                        Respondent,

                           Minnesota Pollution Control Agency,
                                      Respondent.

                                  Filed January 30, 2017
                                         Affirmed
                                     Schellhas, Judge

                            Minnesota Pollution Control Agency
                                 Permit No. MN0021571

Kathryn M. Hoffman, Elizabeth R. Lawton, Minnesota Center for Environmental
Advocacy, St. Paul, Minnesota (for relator)

Francis J. Eggert, Winsted, Minnesota (for respondent City of Winsted)

Lori Swanson, Attorney General, Max H. Kieley, Ann E. Cohen, Assistant Attorneys
General, St. Paul, Minnesota (for respondent Minnesota Pollution Control Agency)

         Considered and decided by Schellhas, Presiding Judge; Ross, Judge; and Jesson,

Judge.

                                     SYLLABUS

         Because 40 C.F.R. § 122.44(d)(1)(i)-(iii) (2016) are ambiguous regarding the data

that the Minnesota Pollution Control Agency must consider in determining whether

activity under a permit has the reasonable potential to cause or contribute to a violation of
water-quality standards, we defer to the agency’s reasonable interpretation of those

regulations.

                                     OPINION

SCHELLHAS, Judge

       In this certiorari appeal, relator challenges a National Pollutant Discharge

Elimination System/State Disposal System (NPDES/SDS) permit that respondent

Minnesota Pollution Control Agency (MPCA) issued to respondent City of Winsted (city)

for its wastewater treatment plant, asserting that the MPCA failed to comply with the

requirements of the federal Clean Water Act (CWA) in issuing the permit. We affirm.

                                        FACTS

       Based on its authority to adopt water-quality standards under the CWA and state

statutes, the MPCA adopted river eutrophication standards (RES) in 2014. Eutrophication

is a response to increased phosphorus loading that “is characterized by increased growth

and abundance of algae and other aquatic plants, reduced water transparency, reduction or

loss of dissolved oxygen, and other chemical and biological changes.” Minn. R. 7050.0150,

supb. 4(G) (2015). The RES are designed to protect Minnesota rivers and streams from

excess algae, which can have negative impacts on aquatic life, drinking water, and water-

based recreation. Although increased levels of phosphorus can cause eutrophication, they

do not always do so. Because of this, the RES are not violated unless both an exceedance

of the “cause criterion” (total phosphorus or TP) and at least one of the following five

“response criteria” exist: chlorophyll-a (seston) (Chl-a); five-day biochemical oxygen




                                           2
demand (BOD5), diel dissolved oxygen flux, and pH levels. See Minn. R. 7050.0222, subp.

4b (2015).

      Among other purposes, water-quality standards like the RES are used to set limits

in NPDES permits, which MPCA is authorized to issue under the CWA. On April 22, 2016,

the MPCA issued an NPDES/SDS permit to the city for an existing wastewater treatment

facility (facility), which discharges within the South Fork of the Crow River (South Fork)

watershed. The permit requires the facility to upgrade facility technology and to move its

discharge point from South Lake, which has a severe eutrophication impairment, to a new

discharge location by the expiration of the permit on March 31, 2021.

      The permit authorizes a new discharge location to an unnamed creek that flows into

Crane Creek and then into the South Fork. Specifically, discharge from the facility will

flow through six reaches of water: (1) an unnamed creek (AUID ’999);1 (2) Crane Creek

(first reach) (AUID ’646); (3) Crane Creek (second reach) (AUID ’647); (4) Crane Creek

(third reach) (AUID ’524); (5) South Fork (first reach) (AUID ’512); and (6) South Fork

(second reach) (AUID ’508). The discharge path from the new location joins the existing

drainage path at the third reach of Crane Creek (AUID ’524). Therefore, although

technically designated as a new discharger under the CWA, the new discharge location will

impact the same watershed and several of the same river reaches as the current discharge




1
 Reaches are identified in the permit by aquatic unit identification code (AUID); each code
at issue in this appeal begins with 07010205 followed by a hyphen and a three-digit suffix.
For ease of reference, we use only the three-digit suffix.

                                            3
location, but will not discharge into South Lake, thereby preventing further eutrophication

impairment in that lake.

       Before issuing the permit, the MPCA conducted a “reasonable potential” analysis

under the CWA to investigate whether the discharge would cause a violation of any

applicable water-quality standards, including the RES. The MPCA concluded that a water-

quality-based effluent limit (WQBEL) was necessary to protect the South Fork and set a

monthly average concentration limit for phosphorus of 630 micrograms per liter (μg/L).2

      Before issuing the permit, the MPCA gave public notice of its intent to do so, and

received comments from relator Minnesota Center for Environmental Advocacy (MCEA).

The MCEA expressed a number of concerns, including two that it raises in this appeal. As

relevant here, the MCEA first asserted that the MPCA had insufficient data to determine

whether a WQBEL was necessary for the first five river reaches impacted by the proposed

relocation. In a response to the MCEA’s comments, the MPCA explained that “[t]he South

Fork of the Crow River was used as the point for determining the effluent limit for the

facility because it was the first reach that had sufficient cause (TP) and response (Chl-a)

variable data. Data are not available at every intervening reach; however, scientific

information has shown that the likelihood of seeing an algae response is minimal.” The

MPCA explained that the first two reaches of the Crane Creek are Class 7 waters, which

are not subject to the RES. And the MPCA noted that, although the limit was derived from



2
  The permit also sets a WQBEL in the form of a mass limit of 1,133 kilograms per year
(12-month moving total) designed to protect Lake Pepin. This WQBEL is not at issue in
this appeal.

                                            4
data on the second reach of the South Fork, “river TP loading will be reduced in other . . .

reaches including the [first reach of the] South Fork of the Crow River (AUID 07010205-

512), and [the third reach of] Crane Creek (AUID 07010205-524). Limits set to protect

downstream waters will also benefit intermediate waters.”

       The MCEA’s second assertion relevant to this appeal was that the MPCA had erred

in estimating the background concentration of phosphorus in the South Fork to be 75 μg/L.

In its response to this comment, the MPCA explained that “[b]ackground, in this context,

is a term used to define the condition of a waterbody without point source inputs” and that

“[d]ata in the South Fork of the Crow River were used to characterize the existing river

condition and determine the reductions necessary to meet standards.” The MPCA further

explained that a generally applicable formula that subtracts known point-source

contributions from the river’s total phosphorus loading had resulted in a negative number,

meaning that “[u]nder moderate low flow conditions, more phosphorus is being discharged

into the watershed than is leaving the watershed.” According to the MPCA, “[t]his pattern

is not uncommon in watersheds, and the data provide evidence of nutrient losses through

transport due to uptake by plants, algae, and deposition into sediments.” Because the “[u]se

of a negative number when determining assimilative capacity of a waterbody would not

provide sufficient protection,” the MPCA used “half of the water quality criterion [(75

μg/L)]” as a background concentration, based on its familiarity with background

concentrations in other Minnesota rivers.

       Following the MPCA’s issuance of the permit to the city, the MCEA filed this

certiorari appeal.


                                             5
                                         ISSUES

I.     Is the MPCA’s interpretation of 40 C.F.R. § 122.44(d)(1)(i)-(iii) entitled to
       deference?

II.    Is the MPCA’s estimation of the background phosphorus concentration in the South
       Fork of the Crow River supported by substantial evidence?

                                       ANALYSIS

       The MPCA is the state agency charged with administering and enforcing the CWA.

Minn. Stat. § 115.03, subds. 1, 5 (2016); 40 C.F.R. § 123.25(a) (2016). The CWA’s purpose

“is to restore and maintain the chemical, physical, and biological integrity of the Nation’s

waters.” In re Cities of Annandale & Maple Lake NPDES/SDS Permit Issuance, 731

N.W.2d 502, 509 (Minn. 2007) (Annandale) (quoting 33 U.S.C. § 1251(a) (2000)

(quotation marks omitted)). As part of its responsibilities under the CWA, the MPCA

adopts water-quality standards for Minnesota waters, including the RES adopted in 2014.

See 33 U.S.C. § 1313(c) (2012); Minn. Stat. § 115.03, subds. 1(c), 1(e), 5; Minn. R.

7050.0222, subp. 4b. Water-quality standards “generally establish the desired condition of

a waterway.” In re Alexandria Lake Area Sanitary Dist. NPDES/SDS Permit No.

MN0040738, 763 N.W.2d 303, 309 (Minn. 2009) (Alexandria Lake) (citing 33 U.S.C.

§ 1313 (2006)).

       Water-quality standards are used to determine whether waters are “impaired” within

the meaning of the CWA. See 33 U.S.C. § 1313(d)(1)(A) (2012) (requiring states to list

impaired waters). For impaired waters, the MPCA is required to establish total maximum

daily loads (TMDLs) of particular pollutants. See 33 U.S.C. § 1313(d)(1)(C) (2012).

Water-quality standards are also used, in conjunction with TMDLs, to determine


                                             6
appropriate limits of particular pollutants to be included in NPDES permits, which the

MPCA is authorized to issue under the CWA and state law. 33 U.S.C. § 1342(b)(1) (2012);

Minn. Stat. § 115.03, subds. 1(e), 5. For new sources, an NPDES permit may not be issued

“if the discharge from its construction or operation will cause or contribute to a violation

of water quality standards.” 40 C.F.R. § 122.4(i) (2016). Therefore, if the MPCA

determines that a discharge has “the reasonable potential to cause, or contribute to an

excursion above any State water quality standard,” it must include a WQBEL in an NPDES

permit. 40 C.F.R. § 122.44(d)(1)(i).

       Any person aggrieved by the MPCA’s final decision to issue a permit may seek

review in this court pursuant to sections 14.63 to 14.69 of the Minnesota Administrative

Procedure Act (MAPA). Minn. Stat. § 115.05, subd. 11(1) (2016). Under MAPA, we may

affirm, remand, reverse, or modify any agency decision that is arbitrary or capricious or

affected by error of law. Minn. Stat. § 14.69(d), (f) (2016). Agency decisions are presumed

to be correct, and we accord deference to an agency in its field of expertise. Reserve Mining

Co. v. Herbst, 256 N.W.2d 808, 824 (Minn. 1977).

                                             I.

       The MCEA first asserts that the MPCA violated 40 C.F.R. § 122.44(d)(1)(i)-(iii) by

failing to determine whether there was a reasonable potential for the facility, operating

under the permit, to cause or contribute to a violation or exceedance of water-quality

standards in the first five river reaches that would be impacted by the relocated discharge.

The MPCA responds that it conducted the reasonable-potential analysis required by the

federal regulations on a reach-by-reach basis; that, although limited data were available for


                                             7
some affected river reaches, it concluded based on available data that no reasonable

potential for water-quality standards to be exceeded existed in those reaches; and that the

MCEA wrongly interprets the regulations to require the MPCA to assume that a water body

exceeds eutrophication water-quality standards when insufficient information is available

to make that determination.

       As a threshold matter, the parties disagree on the standard of review and level of

deference to be afforded to the MPCA in applying the federal regulations. Our supreme

court addressed this issue in Annandale, holding that, although courts apply a de novo

standard of review to the interpretation of statutes and regulations, a state agency is entitled

to deference in its interpretation of a federal regulation that it is charged with administering

if the regulation is “unclear or susceptible to different reasonable interpretations, i.e.

ambiguous” and the agency’s interpretation is reasonable. 731 N.W.2d at 515. The supreme

court noted that deference is particularly appropriate when “the MPCA’s training and

expertise [are] necessary to interpret and apply the statute.” Id. at 514 (emphasis omitted).

       The regulations at issue here—40 C.F.R. § 122.44(d)(1)(i)-(iii)—require the MPCA

to include WQBELS in a permit when the MPCA determines that activity under the permit

will cause an exceedance of water-quality standards. More specifically, 40 C.F.R.

§ 122.44(d)(1)(i) provides that an NPDES permit shall include limitations to control “all

pollutants . . . which the [MPCA] determines are or may be discharged at a level which

will cause, have the reasonable potential to cause, or contribute to an excursion above any

State water quality standard, including State narrative criteria for water quality.”

Additionally, 40 C.F.R. § 122.44(d)(1)(ii) provides that, when conducting the reasonable-


                                               8
potential analysis, the MPCA “shall use procedures which account for existing controls on

point and nonpoint sources of pollution, the variability of the pollutant or pollutant

parameter in the effluent, the sensitivity of the species to toxicity testing . . . , and where

appropriate, the dilution of the effluent in the receiving water.” And 40 C.F.R.

§ 122.44(d)(1)(iii) provides that “[w]hen the [MPCA] determines . . . that a discharge

causes, has the reasonable potential to cause, or contributes to an in-stream excursion above

the allowable ambient concentration of a State numeric criteria within a State water quality

standard for an individual pollutant, the permit must contain effluent limits for that

pollutant.”

       Although the language of the regulations at issue plainly requires the MPCA to

conduct a reasonable-potential analysis and include effluent limits under some

circumstances, the language does not address the data on which the reasonable-potential

analysis must be based. “When a statute or regulation is silent on a precise issue, that

silence may be evidence of ambiguity.” Alexandria Lake, 763 N.W.2d at 311. In this case,

we conclude that the silence in the federal regulations regarding the data on which a

reasonable-potential analysis must be based constitutes an ambiguity warranting our

deference to the MPCA’s interpretation and application of those regulations, so long as

reasonable. See Annandale, 731 N.W.2d at 524 (explaining that phrase “cause or contribute

to the violation of water quality standards” is ambiguous and “leaves leeway for the MPCA

to make a range of policy judgments based on the MPCA’s scientific and technical

knowledge”); In re Request for Issuance of SDS Gen. Permit MNG300000, 769 N.W.2d

312, 321 (Minn. App. 2009) (reasoning that the failure of a rule to “provide direction


                                              9
regarding the procedure, form, and content of a nondegradation review results in

ambiguity,” and because the rule “is ambiguous regarding the procedure, form, and content

of a nondegradation review, MPCA’s implementation of the rule is entitled to deference”).

       The MPCA interprets 40 C.F.R. § 122.44(d)(1)(i)-(iii) “as not requiring the agency

to assume a water body violates eutrophication water quality standards if insufficient

information is available to make this determination.” The MPCA obtains data on

phosphorus and response-criteria levels through a monitoring program that collects data

over multiple summers; complete data is not available for all river reaches. In the absence

of complete, reliable data for some of the reaches at issue here, the MPCA considered other

available information to determine whether there was a reasonable potential for exceedance

of water-quality standards. For instance, the MPCA concluded that algae were unlikely to

grow in the unnamed creek based on scientific evidence that algae do not grow in

headwater streams draining less than 50 square kilometers. For the second reach of Crane

Creek, where phosphorus levels exceed the applicable standard but there are no data on

response criteria, the MPCA concluded that there was no reasonable potential for

exceedance of water-quality standards but recommended monitoring and modification of

permit requirements if subsequently available data indicate a reasonable potential for

violation of water-quality standards. See Minn. Stat. § 115.03, subd. 1(e). Applying the

Annandale standard, we conclude that the MPCA’s interpretation and application of 40

C.F.R. § 122.44(d)(1)(i)-(iii) is reasonable and entitled to deference.

       The MCEA argues that, in the absence of complete data for all reaches that will be

affected by the facility, the MPCA was required to gather that data and was precluded from


                                             10
issuing an NPDES permit until it did so. We reject this argument as reflecting an

unreasonable interpretation of the CWA and federal regulations. As the MPCA explains, it

issues NPDES permits every five years and “does not wait indefinitely for perfect data, but

instead makes its best judgment based on the data . . . available and requires monitoring to

confirm its conclusion or to provide the basis for a permit amendment.” See, e.g., Upper

Blackstone Water Pollution Abatement Dist. v. U.S. EPA, 690 F.3d 9, 22 (1st Cir. 2012)

(noting that “neither the CWA nor EPA regulations permit the EPA to delay issuance of a

new permit indefinitely until better science can be developed, even where there is some

uncertainty in the existing data”).

                                             II.

         Secondly, the MCEA asserts that substantial evidence does not support the MPCA’s

estimation of the background concentration of phosphorus in the South Fork to be 75 μg/L.

Substantial evidence is “(1) such relevant evidence as a reasonable person might accept as

adequate to support a conclusion; (2) more than a scintilla of evidence; (3) more than some

evidence; (4) more than any evidence; or (5) the evidence considered in its entirety.” Minn.

Ctr. for Envtl. Advocacy v. Minn. Pollution Control Agency, 644 N.W.2d 457, 466 (Minn.

2002).

         The MPCA explained in response to the MCEA’s comments on the permit that the

second reach of the South Fork “is downstream of several wastewater treatment plants;

therefore, the monitored flow, concentration, and load of TP in this reach can be attributed

to both point sources and nonpoint sources.” The MPCA also explained that “[i]n order to

figure out the river characteristics without point sources, (i.e. background) one can subtract


                                             11
out the known point source contributions.” But, as the MPCA further explained, that

subtraction resulted in a negative number, meaning that, “[u]nder moderate low flow

conditions, more phosphorus is being discharged into the watershed than is leaving the

watershed.” Because the subtraction formula yielded a negative number, the MPCA

applied an MPCA procedure for implementing RES in NPDES facility permits to estimate

the background concentration as 75 μg/L. The MPCA noted that “[t]hroughout the state it

is not unusual to see phosphorus concentrations at approximately half of the phosphorus

criterion during low flow conditions, especially in watersheds that are not point source

dominated.” The MPCA also notes that the estimated background concentration applied is

consistent with an 80 μg/L background concentration that the MPCA was able to measure

in the North Fork of the Crow River, which is downstream of the South Fork. This is

substantial evidence supporting the MPCA’s use of a 75 μg/L background concentration

for the South Fork of the Crow River in calculating the WQBEL in the permit.

                                     DECISION

       We defer to the MPCA’s reasonable interpretation and application of 40 C.F.R.

§ 122.4(d)(1)(i)-(iii) to not require the agency to assume that water-quality standards will

be exceeded in the absence of sufficient data to make that determination. And we conclude

that the estimation of background phosphorus concentration in the South Fork is supported

by substantial evidence. Accordingly, we affirm the MPCA’s decision to issue the permit.

       Affirmed.




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