3.1 Clean Water Act, Safe Drinking Water Act & NPDES Permitting

Clean Water Act, Safe Drinking Water Act & NPDES Permitting

Water and wastewater operators in Oregon stand at the operational intersection of two comprehensive federal environmental statutes: the Federal Water Pollution Control Act (commonly known as the Clean Water Act or CWA, 33 U.S.C. § 1251 et seq.) and the Safe Drinking Water Act (SDWA, 42 U.S.C. § 300f et seq.). While both acts protect public health and ecological integrity, their regulatory mechanisms, administrative oversight, and points of compliance differ fundamentally.

In the State of Oregon, the United States Environmental Protection Agency (EPA) has formally delegated primacy (primary enforcement authority) to two separate state administrative agencies:

1. Oregon Department of Environmental Quality (DEQ): Under Oregon Revised Statutes (ORS) Chapter 468B and Oregon Administrative Rules (OAR) Chapter 340, DEQ administers the National Pollutant Discharge Elimination System (NPDES) permitting program, state Water Pollution Control Facilities (WPCF) permits, statewide water quality standards, and wastewater operator certification (OAR Chapter 340, Division 049).
2. Oregon Health Authority (OHA) Public Health Division, Drinking Water Services (DWS): Under ORS Chapter 448 and OAR Chapter 333, Division 061, OHA oversees public water systems, enforces drinking water maximum contaminant levels, inspects treatment infrastructure, and certifies drinking water operators.

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|                               FEDERAL ENVIRONMENTAL MANDATE                             |
|                                                                                         |
|             Clean Water Act (CWA)                      Safe Drinking Water Act (SDWA)   |
|                 [33 U.S.C. § 1251]                           [42 U.S.C. § 300f]         |
|                         |                                             |                 |
|                         v                                             v                 |
|                 U.S. EPA Region 10                           U.S. EPA Region 10         |
+-------------------------+---------------------------------------------+-----------------+
                          | Delegated State Primacy                     | Delegated State Primacy
                          v                                             v
+---------------------------------------------+   +---------------------------------------+
|        OREGON DEQ (WATER QUALITY)           |   |       OREGON HEALTH AUTHORITY (OHA)   |
|       ORS 468B / OAR Chapter 340            |   |         ORS 448 / OAR Chapter 333     |
|  - NPDES Municipal & Industrial Permits     |   |  - Public Water Systems (PWS) Rules   |
|  - Secondary Treatment Standards            |   |  - Primary MCLs & Treatment Techniques|
|  - OERS Spill Notification (1-800-452-0311) |   |  - Secondary Standards (SMCLs)        |
|  - Wastewater Certification (Div 049)       |   |  - Drinking Water Cert (Div 061)      |
+---------------------------------------------+   +---------------------------------------+

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Oregon NPDES Permitting Structure

Section 402 of the Clean Water Act prohibits any point source discharge of pollutants into navigable waters of the United States without an authorized NPDES permit. In Oregon, DEQ administers this framework through two primary regulatory permit mechanisms governed by OAR Chapter 340, Division 045:

1. Individual NPDES Permits

Individual permits are tailored specifically to a single facility, such as a municipal Publicly Owned Treatment Works (POTW) or a major industrial processing plant. The permit terms reflect the facility's specific design capacity, influent wastewater characteristics, treatment processes, and the assimilative capacity of the receiving waterbody. An individual municipal permit is traditionally organized into structured schedules:

• Schedule A: Waste discharge limitations, including numerical limits for flow, biochemical oxygen demand, total suspended solids, pH, bacteria, total residual chlorine, and receiving water-specific limits (e.g., nutrients and thermal wasteload allocations).
• Schedule B: Minimum monitoring and analytical reporting schedules, specifying sample collection locations (influent headworks, primary effluent, final outfall), collection types (24-hour flow-proportioned composite vs. discrete grab), and testing frequencies.
• Schedule C: Compliance schedules detailing binding engineering deadlines for plant upgrades, facilities planning, or toxicity reduction evaluations.
• Schedule D: Special operational conditions, including industrial pretreatment program administration, inflow and infiltration (I/I) abatement requirements, emergency response plans, and biosolids management guidelines.

2. General NPDES & WPCF Permits

General permits are developed for categories of discharges that exhibit similar operational profiles, waste characteristics, and standard treatment methodologies. Rather than negotiating individual terms, qualifying facilities submit an application for coverage under a pre-established permit category:

• 100-J: Cooling water discharges.
• 200-J: Filter backwash water from drinking water treatment plants.
• 300-J, 400-J and 900-J: Fish hatcheries, log ponds and seafood processing.
• 1200-Z (and 1200-A for sand and gravel operations): Industrial stormwater.
• 1200-C (and 1200-CA for public agencies): Construction stormwater for projects disturbing one or more acres.
• WPCF Permits: State-issued Water Pollution Control Facilities permits apply to systems that discharge wastewater to land, subsurface drainfields, evaporative lagoons, or reclaimed water reuse systems with no direct point source discharge to surface waters.

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Core NPDES Parameters & Secondary Treatment Standards

Municipal wastewater treatment plants must satisfy federal technology-based Secondary Treatment Standards (codified at 40 CFR Part 133 and written into every Oregon municipal NPDES permit; Oregon's water quality rules in OAR 340-041 add basin-specific minimum design criteria and water quality-based limits). These standards establish minimum legal performance levels for secondary biological treatment, irrespective of the receiving stream's assimilative capacity.

Total Residual Chlorine & Chemical Dechlorination

Chlorine is an exceptionally effective disinfectant, but free chlorine and chloramines are toxic to salmonids and cold-water aquatic life at trace concentrations (EPA National Ambient Water Quality Criteria set chronic freshwater thresholds at $11 \ \mu\text{g/L}$ and acute thresholds at $19 \ \mu\text{g/L}$). Consequently, Oregon NPDES permits frequently establish stringent water quality-based effluent limits (WQBELs) for Total Residual Chlorine (TRC) that approach or undercut analytical detection limits (e.g., non-detect or $< 0.02 \text{ mg/L}$).

To comply, treatment plants practicing chlorination must operate an active chemical dechlorination system downstream of the chlorine contact chamber. Dechlorination is accomplished using sulfur-based reducing agents:

• Sulfur Dioxide Gas ($SO_2$): Gas chlorinator-style vacuum feed system: $\text{SO}_2 + \text{H}_2\text{O} \rightarrow \text{HSO}_3^- + \text{H}^+$ $\text{HOCl} + \text{NaHSO}_3 \rightarrow \text{NaCl} + \text{H}_2\text{SO}_4$
• Sodium Bisulfite Liquid ($NaHSO_3$) or Sodium Metabisulfite ($Na_2S_2O_5$): Liquid metering pump systems that react instantaneously with both free available chlorine and combined chloramines. Operators must tightly modulate bisulfite feed; under-dosing results in lethal chlorine residual violations, whereas severe overdosing consumes dissolved oxygen in the effluent channel ($1 \text{ mg/L}$ of excess bisulfite scavenges roughly $0.15 \text{ mg/L}$ of dissolved oxygen) and depresses effluent pH.

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Monitoring, NetDMR Reporting & Spill Notification Protocols

Compliance with an NPDES permit requires continuous verification through rigorous laboratory analysis and regulatory documentation:

NetDMR Electronic Reporting

Individual NPDES permittees in Oregon report self-monitoring data electronically through EPA's NetDMR system through October 2026 and move to DEQ's Your DEQ Online system in November 2026; general permit and WPCF permittees are moving to Your DEQ Online on DEQ's rolling schedule. Facilities submit Discharge Monitoring Reports (DMRs) detailing daily maximums, monthly averages, geometric means, and analytical sample counts. Under Oregon's standard NPDES general conditions, monthly DMRs are signed and certified by an authorized representative and submitted by the 15th day of the month following the monitoring period, unless Schedule B of the permit says otherwise.

Spill, Bypass & Sanitary Sewer Overflow (SSO) Notifications

Unpermitted discharges of untreated or partially treated wastewater—including collection system overflows caused by fats, oils, and grease (FOG), root intrusion, structural pipe collapse, pump station power failure, or storm-driven hydraulic inundation—represent critical threats to public health and receiving waters.

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Safe Drinking Water Act (SDWA) Standards

The Safe Drinking Water Act establishes public health safeguards across drinking water distribution and treatment. OHA Drinking Water Services enforces these provisions under OAR Chapter 333, Division 061.

+-----------------------------------------------------------------------------------------+
|                           DRINKING WATER REGULATORY DIVISIONS                           |
|                                                                                         |
|  PRIMARY STANDARDS (NPDWRs)                             SECONDARY STANDARDS (NSDWRs)    |
|  - Legally Enforceable Health Mandates                  - Non-Enforceable Aesthetic Goals|
|  - Maximum Contaminant Levels (MCLs)                   - Cosmetic, Taste, Odor, Scaling |
|  - Treatment Techniques (TT: Turbidity, CT)             - Secondary MCLs (SMCLs)         |
|  - Lead & Copper Rule (Action Levels)                  - Iron (0.3 mg/L), Mn (0.05 mg/L)|
|  - Disinfection Byproducts (TTHM, HAA5)                 - TDS (500 mg/L), pH (6.5 - 8.5) |
+-----------------------------------------------------------------------------------------+

Primary vs. Secondary Standards

• National Primary Drinking Water Regulations (NPDWRs): Legally enforceable standards protecting consumers against biological, chemical, radiological, and physical contaminants. EPA and OHA establish Maximum Contaminant Level Goals (MCLGs)—non-enforceable health targets set at levels where no known adverse human health effects occur (with an adequate margin of safety, e.g., zero for known carcinogens and microbial pathogens). The enforceable standard is the Maximum Contaminant Level (MCL), set as close to the MCLG as technologically and economically feasible using the Best Available Technology (BAT).
• Treatment Techniques (TT): Enforceable procedures mandated when it is economically or technologically unfeasible to measure a specific contaminant at trace concentrations. Under the Surface Water Treatment Rule (SWTR), rather than testing directly for Giardia lamblia or Cryptosporidium, water utilities must achieve specific combined filter effluent turbidity limits (e.g., $\le 0.3 \text{ NTU}$ in at least $95\%$ of monthly samples, never exceeding $1.0 \text{ NTU}$) and document disinfectant contact time ($CT$).
• National Secondary Drinking Water Regulations (NSDWRs): Non-enforceable aesthetic guidelines called Secondary Maximum Contaminant Levels (SMCLs). SMCLs control contaminants that cause offensive taste, odor, color, skin or tooth discoloration, or plumbing corrosion.

Lead and Copper Rule (LCR / LCRI)

Under OAR 333-061-0034 and federal regulations, lead and copper are regulated via Action Levels (AL) rather than standard MCLs, evaluated at the 90th percentile of tap samples collected from targeted high-risk residences (Tier 1 sites containing lead service lines, lead interior plumbing, or copper pipe with lead solder installed between 1983 and 1988):

• Lead Action Level: $0.015 \text{ mg/L}$ ($15 \ \mu\text{g/L}$). (The Lead and Copper Rule Improvements lower the lead action level to $0.010 \text{ mg/L}$ beginning November 1, 2027.)
• Copper Action Level: $1.3 \text{ mg/L}$ ($1300 \ \mu\text{g/L}$).

If the lead or copper concentration in more than $10\%$ of collected tap samples exceeds the Action Level, the utility has not committed an immediate violation of an MCL, but is legally triggered into mandatory operational interventions: installing or optimizing Optimal Corrosion Control Treatment (OCCT) (e.g., pH adjustment or orthophosphate dosing), performing water quality parameter (WQP) testing in the distribution system, conducting community-wide public education campaigns, and executing lead service line inventories and replacements.

Revised Total Coliform Rule (RTCR)

The RTCR serves as the primary regulatory indicator of microbial integrity in distribution systems. Systems test for the presence or absence of total coliform bacteria. If a routine sample tests positive for total coliforms:

1. The laboratory must immediately test that culture for Escherichia coli.
2. The utility must collect a set of repeat samples within 24 hours: one at the original tap location, one within five service connections upstream, and one within five service connections downstream.
3. The utility must collect raw source water samples under the Ground Water Rule (if applicable).
4. Oregon calls the RTCR assessments coliform investigations (OAR 333-061-0078). A Level 1 investigation, done by the water supplier, is triggered when more than 5.0 percent of a month's samples are total coliform-positive (systems taking 40 or more samples), when two or more are positive (systems taking fewer than 40), or when required repeat samples are missed. A Level 2 investigation, done by OHA or an approved party, is triggered by an E. coli MCL violation or a second Level 1 trigger within 12 months. The E. coli MCL is violated when an E. coli-positive routine sample is followed by a total coliform-positive repeat, when a total coliform-positive routine is followed by an E. coli-positive repeat, when repeats are not taken after an E. coli-positive routine, or when a total coliform-positive repeat is not tested for E. coli.

Disinfection Byproducts Rules (Stage 1 & Stage 2 DBPR)

When chlorine disinfectants interact with naturally occurring organic matter (NOM) such as humic and fulvic acids derived from decaying forest vegetation, chemical substitution reactions generate halogenated Disinfection Byproducts (DBPs), which present chronic carcinogenic and reproductive risks:

• Total Trihalomethanes (TTHM): Chloroform, bromodichloromethane, dibromochloromethane, and bromoform. MCL = $0.080 \text{ mg/L}$ ($80 \ \mu\text{g/L}$).
• Five Haloacetic Acids (HAA5): Monochloroacetic, dichloroacetic, trichloroacetic, monobromoacetic, and dibromoacetic acids. MCL = $0.060 \text{ mg/L}$ ($60 \ \mu\text{g/L}$).

Compliance under the Stage 2 DBPR is calculated using a Locational Running Annual Average (LRAA), wherein the running average of four consecutive calendar quarters is computed independently at each specific monitoring location in the distribution system. In addition, utilities must monitor Operational Evaluation Levels (OELs). An OEL exceedance occurs when a calculated projection: $\text{OEL} = \frac{\text{Quarter } n-2 + \text{Quarter } n-1 + 2 \times (\text{Current Quarter } n)}{4}$ exceeds the MCL, signaling that treatment optimization (e.g., enhanced coagulation to remove organic precursors, main flushing, or chlorine dose reduction) is required before a formal regulatory violation occurs.

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Consumer Confidence Reports & Public Notification Tiers

Public water systems are legally accountable for keeping the public informed regarding water quality, treatment performance, and health risks:

Consumer Confidence Reports (CCR)

Under OAR 333-061-0043, all community water systems must prepare and deliver an annual drinking water quality report to all billing customers by July 1 of each year. The CCR must report all detected regulated and unregulated contaminants, compare detected values against MCLs and MCLGs, identify the primary watershed or groundwater source, summarize compliance with treatment techniques, provide educational advisories for immunocompromised individuals, and report lead levels detected during recent monitoring rounds.

Public Notification (PN) Compliance Tiers

When a public water system violates drinking water standards, federal regulations (40 CFR Part 141, Subpart Q) and Oregon rules (OAR 333-061-0042) dictate strict timelines and mandatory methods for public notification based on the severity of the threat:

+-----------------------------------------------------------------------------------------+
|                        DRINKING WATER PUBLIC NOTIFICATION TIERS                         |
|                                                                                         |
|  TIER 1: IMMEDIATE ACUTE HAZARD (Within 24 Hours)                                       |
|  - Distribution via Broadcast Media, Reverse 911, Door-to-Door Hand Delivery           |
|  - E. coli MCL Violations; Nitrate/Nitrite MCL Exceedance (10 mg/L / 1 mg/L)            |
|  - Chlorine Dioxide MRDL Exceedance at Entry Point; Waterborne Disease Outbreaks        |
|  - Turbidity TT Exceedance where Consultation Establishes Imminent Risk                 |
|                                                                                         |
|  TIER 2: NON-ACUTE HEALTH HAZARD (Within 30 Days)                                       |
|  - Direct Mail, Billing Insert, or Direct Delivery (Repeated Quarterly)                |
|  - Chemical/Radiological MCL Exceedances (TTHM, HAA5, Arsenic, Fluoride)                |
|  - Surface Water Treatment Technique Violations Not Escalated to Tier 1                 |
|                                                                                         |
|  TIER 3: MONITORING & ADMINISTRATIVE INFRACTIONS (Within 12 Months)                     |
|  - Annual Notice or Consolidated Publication in Annual Consumer Confidence Report (CCR) |
|  - Failure to Perform Scheduled Water Quality Monitoring or Complete Analytical Testing |
|  - Operating Under an Approved Regulatory Variance or Exemption                         |
+-----------------------------------------------------------------------------------------+

1. Tier 1 (Immediate Acute Threat): Notice must be issued as soon as practical, but no later than 24 hours after the utility learns of the violation. Utilities must coordinate directly with OHA and deploy broad-scale communication tools: local television, radio, reverse 911 telephone networks, website banners, social media alerts, and physical hand delivery. Applies to: E. coli MCL exceedances; failure to test for E. coli following a coliform-positive repeat sample; nitrate ($10 \text{ mg/L}$) or nitrite ($1 \text{ mg/L}$) MCL exceedances; chlorine dioxide maximum residual disinfectant level (MRDL) exceedances at the treatment plant entry point; acute turbidity exceedances under the SWTR; or confirmed waterborne disease outbreaks.
2. Tier 2 (Non-Acute Violations): Notice must be issued within 30 days of learning of the violation (repeated quarterly for as long as the violation persists) via direct mail, newspaper publication, or water bill inserts. Applies to: all chemical, physical, and radiological MCL exceedances (such as chronic TTHM/HAA5 or arsenic exceedances); and treatment technique failures that do not pose an imminent acute hazard.
3. Tier 3 (Monitoring & Administrative Infractions): Notice must be provided within 12 months of learning of the violation, typically fulfilled through inclusion in the annual Consumer Confidence Report. Applies to: failure to conduct routine regulatory compliance sampling; laboratory analytical or reporting errors; or operation under an approved compliance variance or exemption.