Navajo Nation Low-Threat General Permit Draft Factsheet May 2023 NNG990001 NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM FACT SHEET MAY 2023 PART I: ELIGIBILITY A. Background The existing Navajo Nation Low-Threat General Permit was issued on March 23, 2018 with an expiration date of April 30, 2023. EPA is now proposing to renew this permit. The proposed permit is based on information gathered during the previous five years, as well as applicable laws and regulations. The Federal Clean Water Act (CWA) states that discharge of pollutants to Waters of the United States from any point source is prohibited, unless the discharge is in compliance with a National Pollutant Discharge Elimination System (NPDES) permit. According to Title 40 of the Code of Federal Regulations (CFR) Section 122.28(a)(2), the United States Environmental Protection Agency (USEPA) may promulgate general permits to cover categories of point sources having the following common elements: • Sources that involve the same or substantially similar types of operation. • Sources that discharge the same types of wastes or engage in the same type of sludge use or disposal. • Sources that require the same effluent limitations or operating conditions, or standards for sewage sludge use or disposal • Sources that require the same monitoring where tiered conditions may be used for minor differences within a class (e.g., size or seasonal activity) • Sources that are more appropriately regulated by a general permit This general permit for low threat discharges (LTGP) will provide timely authorization for discharges to Waters of the United States and when properly managed, these discharges will not adversely impact water quality, designated uses, or the environment. Use of a general permit for low threat discharges allows the permitting authority and dischargers to allocate resources in a more efficient manner, obtain timely permit coverage, and avoid issuing resource intensive individual permits to each facility. Additionally, the LTGP will provide potential permittees with information about discharge requirements needed to qualify for coverage under the general permit, providing greater certainty and efficiency to the regulated community while ensuring consistent permit conditions for comparable facilities. Page 1 of 19 ------- Navajo Nation Low-Threat General Permit Draft Factsheet May 2023 NNG990001 Pursuant to Section 402 of the CWA, EPA is proposing issuance of this NPDES General Permit for low threat discharges to all Waters of the United States within the Navajo Nation. B. Definition of Low-Threat Discharge Low threat discharges that may be authorized by this LTGP are relatively pollutant-free wastewaters that present no or minimal threat to receiving water quality when managed properly. Discharges that are eligible for coverage under the LTGP are intermittent, low volume, and/or short-term in nature. Discharges covered under the LTGP do not contain pollutants in concentrations that cause, have the reasonable potential to cause, or contribute to an excursion above any applicable water quality criterion and are consistent with federal antidegradation policy. Discharges covered under this permit should not create environmental damage or nuisance effects. The requirements of the LTGP ensure that discharges are managed such that they pose minimal threat to water quality in receiving waters. The implementation of numeric permit limits as well as standard technology treatments and/or best management practices (BMPs) are methods to minimize the impact of some discharges, allowing them to qualify for coverage under this LTGP. C. Eligible Discharges Discharges to Waters of the United States that meet the definition of low threat as defined in Section B. above shall be eligible for coverage under the LTGP and may include, but are not limited to, the following categories of discharges: • Potable water supply system discharges: o Discharges associated with fire hydrant flushes/testing o Discharges associated with system operation and maintenance activities (wells, pipelines, tanks, reservoirs) o Discharges resulting from potable water filter backwash operations o Discharges associated with system repair of water supply pipelines o Discharges from cleaning or flushing of water supply wells, pipelines, tanks and reservoirs o Discharges from hydrostatic testing of pipelines, tanks, and reservoirs o Discharges resulting from initial system startup and routine startup o Discharges resulting from sampling of influent flow, pressure releases, etc. Page 2 of 19 ------- Navajo Nation Low-Threat General Permit NNG990001 Draft Factsheet May 2023 • Hydrostatic testing of newly constructed pipelines, tanks, and reservoirs used for purposes other than pertaining to a potable water system • Construction dewatering of water where sediment and naturally occurring parameters (e.g. metals, salts, or other physical parameters such as pH, temperature, etc.) in the ground water are the only pollutants of concern • Groundwater discharges (not for or from remediation) o Pump/well testing o Well development water o Dewatering discharges • Other discharges that meet the definition of low-threat as determined by EPA In order to be covered under the LTGP the applicant will identify any contaminants of concern (naturally occurring or otherwise) that are believed to be present in the discharge and describe the treatment and Best Management Practices (BMPs) that will be used to ensure that the discharge does not cause a violation of the effluent limits or other specified requirements in the permit, or cause effects that are detrimental to the receiving water body or surrounding environment that are in violation of this LTGP. D. Ineligible Discharges Discharges that EPA does not consider low-threat for the purposes of this LTGP include but are not limited to: • Discharges containing domestic wastewater • Discharges resulting from non-potable water filter backwash operations • Discharges near or adjacent to hazardous waste sites, soil or groundwater remediation sites • Discharge from mining activities • Discharges from leaking chemical and fuel tanks • Discharges of industrial waste • Discharges that would require extensive biological or chemical treatment in order to meet effluent limits or relevant water quality standards • Discharges of non-contact cooling water • Discharges of ongoing operation of permanent domestic or industrial water or wastewater treatments plants or industrial processes • Discharges that are uncharacterized or insufficiently characterized to establish suitability for coverage as low-threat Page 3 of 19 ------- Navajo Nation Low-Threat General Permit NNG990001 Draft Factsheet May 2023 • Discharges containing additives associated with water treatment or industrial use (other than chlorine for potable water use) • Discharges of groundwater, surface water, or potable water associated with the on- going testing of pipes, tanks or vessels that have been used to store or transport petroleum, natural gas, or any other substance other than potable water • Discharge of accidental or unplanned releases from any source • Discharge of wastewater with pollutants of concern other than those for which effluent limits are specified in this LTGP • Discharge of wastewater that is likely to adversely affect federally-listed threatened or endangered species or critical habitat. • Any other discharges that do not meet the definition of low-threat as determined by the Regional Administrator pursuant to this LTGP E. Geographic Coverage of Permit This permit provides coverage for low threat discharges that occur in the Navajo Nation including Navajo Nation Reservation lands in Arizona, New Mexico and Utah where EPA Region 9 is the NPDES permitting authority. A map of the lands covered by this permit is attached as an attachment to the permit for ease of determination of geographic coverage of the permit. For such discharges in Region 9 under the NPDES permitting jurisdiction of a State but outside the areas of coverage above, the State NPDES permitting authority must be contacted to provide coverage under a State-issued NPDES low threat or de minimis permit or under a State-issued individual permit. PART II: AUTHORIZATION REQUIREMENTS A. Category of Discharge: Discharges that meet the requirement for eligibility pursuant to PART I. C. above and fall into one the following categories are authorized for coverage under the LTGP. 1. Category I A discharge from a single outfall of 0.10 MGD or less, AND A discharge of 30 days or less. 2. Category II Page 4 of 19 ------- Navajo Nation Low Draft Factsheet May 2023 -Threat General Permit NNG990001 a. A discharge from a single or multiple outfalls of 0.50 MGD or less (cumulative if multiple outfalls), AND A discharge of 30 days or less. b. A discharge from a single or multiple outfalls of 0.05 MGD or less, AND A discharge of 30 days or more (continuous or intermittent). B. Application Requirements: 1. Noti ce of Intent (NOI) To apply for coverage under this LTGP the applicant in either Category I or Category II must submit a Notice of Intent (NOI) letter and provide all of the supplemental information that it requires pursuant to 40 CFR Section 122.28(b). The requirements are also described in the LTGP itself. In particular, the applicant must provide facility information, discharge information, receiving water information, and data that are representative of the discharge. For all discharge types, the applicant must certify that the discharge complies with screening criteria that are described in the LTGP permit. For instance, the applicant must certify that the discharge contains no known contaminants of concern (COCs). For potable water related discharges, the applicant must also certify that the discharge meets federal Maximum Contaminant Levels (MCLs). See below for the screening requirements of Category I and Category II dischargers. Table 1. NOI Screening for Category I discharges Parameter Units Screening Value Notes Total Residual Chlorine l-ig/L 11 (4-day average) 19 (1-hour average) (1) pH S.U. within the range 6.0 to 9.0 Turbidity NTUs 50 Electrical conductivity @ 25 °C (imhos/cm (not applicable) (4) Dissolved Oxygen mg/L No less than 5 Page 5 of 19 ------- Navajo Nation Low-Threat General Permit NNG990001 Draft Factsheet May 2023 Constituents with MCLs — The discharge meets MCLs for all constituents (2) COCs and water treatment additives The discharge has no known COCs and does not contain additives apart from chlorine. (2) Color Odor not objectionable (3) Floating solids Settled solids Suspended solids Foam Other indicators of pollution no pollutants present to settle to form objectionable deposits; float as debris, scum, oil, or other matter forming nuisances (3) Oil sheen Absent (3) Total Suspended Solids mg/L 30 (30-day average) 45 (7-day average) 1. For chlorinated discharges, if discharge does not meet the chlorine discharge limit, the NOI must provide the method of de-chlorination that will be used to meet the limit. 2. Based on data 3. Based on visual inspection 4. Monitoring for electrical conductivity only, no screening value applies NOI Screening for Category II dischargers In addition to the screening requirements for Category I dischargers, Category II dischargers must conduct a priority pollutant scan to determine whether there is reasonable potential for discharge of pollutants considered to be of principal importance for control under the CWA; a list of these pollutants is provided as Attachment A to 40 CFR Part 423. For Category I discharges, the complete NOI must be submitted a minimum of 14 days before commencing the planned discharge; for Category II discharges, the complete NOI must be submitted a minimum of 30 days before commencing the planned discharge. Page 6 of 19 ------- Navajo Nation Low-Threat General Permit NNG990001 Draft Factsheet May 2023 C. Best Management Practices Plan (BMPP) Pursuant to 40 CFR Section 122.2, Best Management Practices (BMPs) means schedules of activities, prohibitions of practices, maintenance procedures, and other management practices to prevent or reduce the pollution of "waters of the United States." BMPs may include, but are not limited to, treatment requirements, operating procedures, or practices to control plant site runoff, spillage, etc. In the context of the LTGP such BMPs primarily include but are not limited to flexible practices or procedures that can be used to prevent pollutants from entering receiving waters or other effects such as erosion and flooding. The Best Management Practices Plan (BMPP) must describe the BMPs that will be implemented to ensure that the discharges proposed for coverage under this LTGP do not threaten receiving water quality. The BMPP must be prepared before or concurrently with when the NOI letter is submitted to EPA for permit coverage. The requirements for the BMPP for all discharges as well as specific requirements for particular categories or classes of discharges (e.g., hydrostatic test discharges) are specified in the LTGP. D. Authorization and Termination 1. Authorization Applicants must submit a complete NOI letter requesting coverage at least fourteen (14) or at least thirty (30) days before the expected start of discharge based on the Category of Discharge as provided in Table 2. below Table 2: NOI Submittal Deadlines/Discharge Authorization Dates Category NOI Submission Deadline Discharge Authorization Date1 Category I: - discharges of 0.10 MGD or less from a single outfall AND - 30 days or less duration. As soon as possible but 14 days before commencing planned discharge. 14 days after receipt of the application from EPA, unless EPA contacts the applicant to deny coverage or request additional information. The effective date of permit coverage under the permit shall begin on date of first discharge and terminates 30 days after the date of the first Page 7 of 19 ------- Navajo Nation Low-Threat General Permit NNG990001 Draft Factsheet May 2023 discharge. If the first discharge does not occur within 180 days of receipt of application the permittee must re-apply for coverage. Category Ha: - discharges of 0.50 MGD or less from a single or multiple outfalls AND - 30 days or less duration. A minimum of 30 days prior to commencing planned discharge. 30 days after receipt of the application from EPA, unless EPA contacts the applicant to deny coverage or request additional information. The effective date of permit coverage under the permit shall begin on date of first discharge and coverage terminates 30 days after the date of the first discharge. If the first discharge does not occur within 180 days of receipt of application the permittee must re-apply for coverage. Category lib: - discharges of 0.05 MGD or less from a single or multiple outfalls AND - 30 days or more duration.1 A minimum of 30 days prior to commencing planned discharge. 30 days after receipt of the application from EPA, unless EPA denies coverage or requests additional information.2 1. The duration of permit coverage shall not exceed the life of the Permit. The applicant shall reapply for coverage when the Permit is renewed. 2. Based upon review of the NOI or other information, EPA may delay authorization for further review, notify the applicant that additional effluent limitations are necessary, or may deny coverage under this permit and require submission of an application for an individual NPDES permit. In these instances, EPA will notify the applicant (in writing) of the delay, of the need for additional effluent limits, or of the request for submission of an individual NPDES permit application. 2. Termination Page 8 of 19 ------- Navajo Nation Low-Threat General Permit Draft Factsheet May 2023 NNG990001 The permittee must provide a complete and accurate Notice of Termination (NOT) to terminate permit coverage. Information required to be included in a NOT is provided in the LTGP in Section 1.3. Authorization terminates automatically 31 days after the commencement of discharge for facilities that obtained coverage under Category I. and II.a. However, permittees under Category I. and II.a. are still required to submit to EPA a complete and accurate NOT within 30 days from the date of first discharge. Otherwise, authorization to discharge under the LTGP terminates at midnight of the day that a complete NOT is processed and the permittee or operator seeking termination is notified coverage under Category lib. Page 9 of 19 ------- Navajo Nation Low-Threat General Permit Draft Factsheet May 2023 PART III: EFFLUENT LIMITATIONS A. Technology-Based Effluent Limits NNG990001 There are two approaches for developing technology-based effluent limits for industrial facilities: (1) using national effluent limitations guidelines (ELGs) and (2) using Best Professional Judgment (BPJ) on a case-by-case basis (in the absence of ELGs). The intent of a technology-based effluent limitation is to require a minimum level of treatment for point sources based on currently available treatment technologies while allowing the discharger to use any available control technique to meet the limitations. Since industrial discharges and discharges from wastewater treatment plants are not eligible to be covered under this LTGP, no ELGs or secondary standards were available to develop technology based effluent limitations. Instead, BPJ was used to derive technology-based effluent limitations proposed in this permit. Discharges that are eligible for coverage under this LTGP are considered high-quality wastewaters that are relatively pollutant-free and pose no or minimal threat to water quality. Technology-based effluent limitations were established for two categories of low-threat discharges that are anticipated: potable water discharges and ground water discharges. EPA anticipates that the wastewater from potable water discharges will not contain contaminants at concentrations of concern apart from residual chlorine or solids that may have settled in the distribution system. Effluent limitations for potable water discharges were established for chlorine, oil and grease, turbidity, settleable solids, suspended solids, and pH. Additionally, the discharge must meet federal MCLs. Wastewater from ground water discharges covered under this LTGP will not contain contaminants apart from naturally-occurring parameters, including sediments, dissolved solids, and turbidity. Effluent limitations for ground water discharges were established for oil and grease, turbidity, settleable solids, dissolved solids, suspended solids, and pH. Flow is limited for all discharges such that no single discharge event shall exceed 0.50 MGD over a period of 30 days or less (of continuous flow), or over 0.05 MGD over a period of 30 days or more (of continuous flow, or intermittent flow). Flow must be monitored during each discharge event. Page 10 of 19 ------- Navajo Nation Low-Threat General Permit Draft Factsheet May 2023 B. Water-Quality Based Effluent Limits NNG990001 CWA section 301(b)(1)(C) requires that permits include any effluent limitations necessary to meet water quality standards. Such water quality standards in the case of this permit includes the current Navajo Nation Water Quality Standards which have been approved by EPA, as well as federal water quality standards that EPA may consider on a best professional judgment basis. With few exceptions (e.g., chlorine), discharges that are eligible for coverage under this LTGP do not contain pollutants in concentrations that cause, have the reasonable potential to cause, or contribute to an excursion above any applicable water quality standard. EPA expects that compliance with other conditions in this permit (e.g., the technology-based limitations, best management practices, narrative limitations, etc.) will result in discharges that meet applicable water quality standards; there are no specific water quality-based limitations (WQBELs) in this LTGP. However, EPA may impose additional, more stringent WQBELs, on a site-specific basis if information suggests that the discharge is not controlled sufficiently to meet applicable water quality standards. C. Narrative Limits Standard narrative limitations based on the Navajo Nation Surface Water Quality Standards are included in the LTGP. D. Standard Permit Conditions Standard permit conditions pursuant to 40 CFR Section 122.41 applicable to all permits issued by EPA Region 9 are included in the LTGP. PART IV: MONITORING AND REPORTING REQUIREMENTS The monitoring and reporting requirements required under the LTGP are for those parameters that are most likely to be of concern in discharges that qualify as low-threat as defined in Part I. B. above, and therefore likely to be found in discharges from entities seeking coverage under this General Permit. The permittee shall submit data monitoring reports electronically using NetDMR (http://www.epa.gov/netdmr) through EPA's Central Data Exchange (CDX), respectively. Electronic submittals shall also be sent via electronic mail to R9NPDES@epa.gov. Permittee's seeking coverage under category I and II. a. (permit coverage duration of no more than 30 days) may submit data monitoring reports via hardcopy with wet signature as an alternative to using Page 11 of 19 ------- Navajo Nation Low-Threat General Permit NNG990001 Draft Factsheet May 2023 NetDMR pursuant to a waiver of the electronic reporting requirement. The request to waive the electronic reporting requirements for the discharge monitoring reports shall be made at the same time as EPA is notified of the initial discharge date. The request must include the NPDES permit number along with the reason for the request. The waiver will allow the permittee to submit hardcopy discharge monitoring reports in lieu of submitting them via NetDMR. The electronic mailing address of the permittee is required. Hardcopies should be submitted to: Attn: Chun Liu US Environmental Protection Agency, Region 9 Enforcement & Compliance Assurance Division, Data Solution Office (Enf 4-1) 75 Hawthorne Street San Francisco, CA 94105 PDF copies of the hardcopy DMRs must also be sent via electronic mail to R9NPDES@epa.gov. The individual limitations and monitoring requirements in the LTGP are listed in Table 3. Below: Page 12 of 19 ------- Navajo Nation Low-Threat General Permit Draft Factsheet May 2023 NNG990001 Table 3. Effluent Limitations and Monitoring Requirements for all Low-threat Discharge Activities. Parameter Units Daily Max. /Min. Limits Monthly Average Limits1 Sample Type23 Monitoring Frequency Notes ALL DISCHARGES Flow MGD Report (MGD) Report (MGD) Metered Continuous (4), (5) (6) pH SU must remain within 6.0 and 9.0 discrete (?) (5) Total Suspended Solids mg/L 30 10 discrete (?) Oil and Grease (8) (?) Turbidity NTUs 50 10 (?) GR< 3UNDWATER DISCHARGES Total Dissolved Solids (Electrical Conductivity @ 25 °C) pmhos/c m (9) Discrete (?) (5) POTABLE WATER DISCHARGES Total Residual Chlorine Hg/L 19 11 (?) (5), (10) 1. Average monthly limit applies to Category discharge reaches 30 days. The permittee si' regardless of monitoring frequency. For ex I discharges, regardless of whether the duration of tall report exceedances of any limits for each parameter ample, monthly limits shall be met even when only Page 13 of 19 ------- Navajo Nation Low-Threat General Permit NNG990001 Draft Factsheet May 2023 monitoring once per month. The permittee may monitor more frequently than required for any parameter. 2. Samples must be collected at a point immediately following discharge from the vessel and prior to commingling with storm water, wastewater, or other flows. For Category I discharges that extend beyond one hour duration, a second sample shall be collected from the last 10% of the effluent. The Discharger must confirm that the EL is met before discharge for field-tested parameters. 3. For hydrostatic testing, grab samples shall be taken of the hydrostatic test water being discharged as it leaves the equipment, piping, or vessels being tested at the beginning and at the end of the discharge and two times during the discharge at evenly spaced time intervals. Each grab sample shall be tested individually, and the highest result reported. 4. The flow must be below the threshold established for each particular Category of discharger as described in Part II. A of the permit 5. Field-testing is permitted, using suitable methods, for flow, pH, total residual chlorine, and electrical conductivity. The permittee shall cease discharge if any of the field-tested parameters exceeds the effluent limitation. 6. Monitor and report only, no numeric effluent limitation. Where no numeric limit is listed, the narrative standards in Part III.2.3 of this permit still apply. The permittee must implement BMPs to control the discharge of these constituents, as appropriate, when they are known or suspected to be present in the discharge. 7. Minimum monitoring frequency of once/discharge for Category I. and II. a. ; once/month for Category lib. 8. Oils, greases, waxes, and floating material shall not create a nuisance or adversely affect beneficial uses. 9. Total Dissolved Solids may be measured indirectly by measuring electrical conductivity. No limit set but monitoring and reporting required. 10. The dechlorination method must be disclosed in the NOI. The Rationale for specific limits provided in the table above are as follows: Flow: The flow must be below the threshold for the particular Category as described in Part II. A. above that the permittee is seeking coverage under. A permittee seeking coverage under Category I. shall not exceed a maximum flow of 0.1 MGD or 100,000 gallons per day from the permitted outfall. A permittee seeking coverage under Category II. a. shall not exceed a maximum cumulative flow of 0.5 MGD or 500,000 gallons per day from the permitted outfall or outfalls. A permittee seeking coverage under Category II. b. shall not exceed a maximum cumulative flow of 0.05 MGD or 50,000 gallons per day from the permitted outfall or outfalls. pH The limit of between 6.0 and 9.0 standard units is based on the minimum secondary treatment standards for wastewater established under 40 CFR Section 122.45 Page 14 of 19 ------- Navajo Nation Low-Threat General Permit NNG990001 Draft Factsheet May 2023 Total Suspended Solids (TSS) The TSS daily maximum limit of 45 milligrams per liter and the monthly average limit of 30 milligrams per liter are based on minimum secondary treatment standards for wastewater established under 40 CFR 133.102(b) Oil and Grease No numeric limits have been established, but the permittee must meet the narrative requirement that the effluent not have oils, greases, waxes, or floating material in amounts that create a nuisance or adversely affect beneficial uses. Turbidity The turbidity daily maximum limit of 50 NTUs and monthly average limit of 10 NTUs is based on best professional judgment (BPJ) taking into account the CWA 304(a) National Recommended Water Quality Criteria, which defer to the narrative statement found in the Red Book Quality Criteria for Water, 1976. Total Dissolved Solids (TDS) No numeric limits have been established, but the permittee must meet the narrative standards requirement that the discharge not produce objectionable color, odor, taste or turbidity; or produce adverse physiological responses in humans, animals or plants. Total Residual Chlorine (TRC) The TRC daily maximum limit of 19 micrograms per liter and the monthly average limit of 11 micrograms per liter are based on the Navajo Nation Surface Water Quality Standards. Electrical Conductivity Electrical conductivity is a measure of the salinity of the effluent, and monitoring is required pursuant to the Colorado River Salinity Control Forum. PART V: ESA AND NHPA A. Endangered Species Act Section 7 of the Endangered Species Act (ESA) of 1973 (16 U.S.C. § 1536) requires federal agencies to ensure that any action authorized, funded, or carried out by the federal agency does not jeopardize the continued existence of a federally listed or candidate species, or result in the destruction or adverse modification of its habitat. Page 15 of 19 ------- Navajo Nation Low-Threat General Permit NNG990001 Draft Factsheet May 2023 The scope of the action authorized by the EPA pursuant to this proposed NPDES permit is to allow discharge from wastewater sources that are classified as low-threat sources. Low-threat discharges are clean or relatively pollutant-free wastewaters that present no or minimal threat to receiving water quality when managed properly. Examples are discharges from hydrostatic testing of new pipelines, and or existing drinking water pipelines using potable water or backflushing of filters at drinking water production wells or facilities, etc. Discharges that are eligible for coverage under the LTGP are generally intermittent, low volume, and/or short-term in nature and do not contain pollutants in concentrations that cause, have the reasonable potential to cause, or contribute to an excursion above any applicable water quality criterion. Discharges covered under this LTGP pose minimal threat to water quality in receiving waters, and so may affect but are not likely to adversely affect federally listed threatened or endangered species, nor result in the destruction or adverse modification of designated critical habitat. Since the specific geographic locations of facilities covered under the LTGP can be anywhere within the Navajo Nation but are generally unknown until an applicant applies for coverage, it is not possible to define an action area for each permitted discharge under the LTGP. However, each applicant must submit information regarding federally-listed or candidate endangered species, and critical habitat found in the action area of the applicant's proposed discharge location. Attachment C of the permit outlines the procedures for each applicant must follow to comply with the requirements of the ESA. B. National Historic Preservation Act Section 106 of the National Historic Preservation Act (NHPA) requires federal agencies to consider the effect of their undertakings on historic properties that are either listed on, or eligible for listing on, the National Register of Historic Places. The scope of the action authorized by the EPA pursuant to this proposed NPDES permit is to allow discharge from wastewater sources that are classified as low-threat sources. Low-threat discharges are clean or relatively pollutant-free wastewaters that present no or minimal threat to water quality for the environment when managed properly. Since the specific geographic locations of facilities covered under the LTGP is generally unknown until an applicant applies for coverage, each applicant must identify any historic properties that are listed on or eligible for listing on, the National Register of Historic Places found in the vicinity of the applicant's proposed discharge or project area, or provide a statement that no such properties were found. If historic properties are found in the vicinity of the of the applicant's proposed discharge or project area, then the applicant then must provide the name and location of such properties to the USEPA and the appropriate State Historic Preservation Officer (SHPO) or Tribal Historic Preservation Page 16 of 19 ------- Navajo Nation Low-Threat General Permit NNG990001 Draft Factsheet May 2023 Officer (THPO) to evaluate. Attachment D of the permit outlines the procedures that each applicant must follow to comply with the requirements of the NHPA. PART VI: OTHER CONSIDERATIONS UNDER FEDERAL LAW A. Antidegradation EPA's antidegradation policy at 40 CFR Section 131.12 requires existing water uses and the level of water quality necessary to protect the existing uses to be maintained. Due to the nature of the discharge activities, BMPs that ensure clean or relatively pollutant-free wastewaters, and the effluent limitations designed to be comparable to wastewater that has received a high level of treatment, it is not expected that the discharge will adversely affect the receiving water. B. Anti-Backsliding Section 402(o) of the CWA prohibits the renewal or reissuance of an NPDES permit that contains effluent limits less stringent than those established in the previous permit, except as provided in the statute. The proposed LTGP does not contain effluent limits less stringent than those established in the previous permit and therefore does not allow backsliding. C. Environmental Justice EPA has conducted a screening level evaluation of the potential impact of this permit using EPA's EJSCREEN tool. As the exact location of potential facilities that may be authorized pursuant to this permit is indeterminate, EPA instead evaluated the demographic characteristics of the population of the Navajo Nation, which indicated that the population may be at relatively higher risk if exposed to environmental contaminants than the national population. Demographic characteristics that showed potentially sensitive scores were a high proportion of minority and low-income population and population with less than high school education. EPA concludes that the facilities authorized to discharge pursuant to this permit are unlikely to contribute to any environmental justice issues, as permit coverage is restricted to facilities that discharge relatively pollutant-free wastewaters that are intermittent, low volume, and/or short-term in nature and present no or minimal threat to water quality for the environment when managed properly. EPA believes that implementing the limits established in this permit which require compliance with the provisions of the Clean Water Act, will ensure full protection of human health and the environment and ensure that the discharges will not cause or contribute to human health risk in the vicinity of the facilities covered by the permit. Page 17 of 19 ------- Navajo Nation Low-Threat General Permit Draft Factsheet May 2023 NNG990001 D. Water Quality Certification Requirements Pursuant to 40 CFR sections 124.53 and 124.54 USEPA is requesting certification from the Navajo Nation, that the proposed permit will meet all applicable water quality standards. The Navajo Nation's water quality certification may contain conditions that will be added the final permit. PART VII: ADMINISTRATIVE INFORMATION A. Administrative Record The Administrative Record for the LTGP and any additional information related to this proposed permitis available upon request at: U.S. Environmental Protection Agency, Region 9 NPDES Permits Section, Water Division (WTR-2-3) 75 Hawthorne Street San Francisco, California 94105 Access to the Administrative record may be arranged by contacting: Gary Sheth at (415) 972-3516 or sheth.gary@epa.gov B. Public Notice and Comment/Public Hearing Pursuant to 40 CFR section 124.10, public notice is the vehicle for informing all interested parties and members of the general public of the contends of a draft NPDES permit or other significant action with respect to an NPDES permit or application. A copy of the proposed draft permit and draft factsheet will be electronically mailed to all potential stakeholders, and a copy of the proposed draft permit and factsheet will also be posted on USEPA Region 9's website at: https://www.epa.gov/npdes-permits/npdes- permits-epas-pacific-southwest-region-9 with a minimum of 30 days provided for interested parties to respond in writing to USEPA. After the closing of the public comment period, USEPA will respond to all significant comments at the time a final permit decision is reached or at the same time a final permit is actually issued. A public hearing may be requested in writing by any interested party. The request should state the nature of the issues proposed to be raised during the hearing. A public hearing will be held if EPA determines there is a significant amount of interest expressed during Page 18 of 19 ------- Navajo Nation Low-Threat General Permit NNG990001 Draft Factsheet May 2023 the 30-day public comment period or when it is necessary to clarify the issues involved in the permit decision. Additionally, a Notice of Availability of Proposed National Pollutant Discharge Elimination System (NPDES) for this General Permit will be published in the Federal Register and will provide instructions on how to submit comments. PART VIII: REFERENCES EPA 2015. Multi-Sector General Permit, https://www.epa.gov/npdes/final-2015-msgp-documents EPA. 1991. Technical Support Document for Water Quality-based Toxics Control. Office of Water, EPA. EPA/505/2-90-001. EPA. 2010. U.S. EPA NPDES Permit Writers 'Manual. Office of Water, EPA. EPA-83 3-K-10-001. Navajo Nation Surface Water Quality Standards 2015. Passed by Navajo Nation Council Resources and Development Committee on May 23, 2017 and approved by EPA on March 17, 2021 USFWS 1998. Endangered Species Consultation Handbook. National Archives and Records Administration Office of the Federal Register 1991. Document Drafting Handbook Colorado River Basin Salinity Control Forum, 2020, Water Quality Standards for Salinity Colorado River System Page 19 of 19 ------- |