NOTE: (The original Water Quality Standards Regulation was filed in the 

Department of State on January 4, 1974, and subsequent amendments were made on 

May 1974, October 1976 and February 1983, November 1987, July 1990, and March 

2003).
TABLE OF CONTENTS

i

PAGE

RULE 1300 TITLE, LEGAL BASIS, DECLARATION OF GOALS AND 

PURPOSES, AND ANTI-DEGRADATION POLICY

1

1300.1 Title 1

1300.2 Legal Basis 1

1300.3 Declaration of Goals and Purposes 1

1300.4 Anti-Degradation Policy 1

RULE 1301 DEFINITIONS AND ACRONYSMS 3

1301.1 Definitions 3

1301.2 Acronyms 23

RULE 1302 CLASSIFICATION OF WATERS OF PUERTO RICO 

ACCORDING TO THE DESIGNATED USES TO BE 

PROTECTED

24

1302.1 Coastal Waters and Estuaries Waters 24

1302.2 Surface Waters 25

1302.3 Ground Waters 25

RULE 1303 WATER QUALITY STANDARDS AND USE 

CLASSIFICATIONS TO BE PROTECTED IN THE WATERS 

OF PUERTO RICO

26

1303.1 Water Quality Standards 26

1303.2 Use Classifications and Water Quality Standards for 

Specific Classifications

34

RULE 1304 INTERMITTENT STREAMS 42

1304.1 General 42

1304.2 Application for Relief 42

1304.3 Requirements for Granting Relief 43

1304.4 Preliminary Determinations 45

1304.5 Public Notice and Opportunity for Public Hearing 45

1304.6 Public Hearings 46

1304.7 Final Determination 46

1304.8 Duration of Relief 47

1304.9 Revocation of Relief 47

1304.10 Monitoring Requirements 47
TABLE OF CONTENTS (Cont.)

ii

PAGE

RULE 1305 MIXING ZONES 48

1305.1 General 48

1305.2 Natural Background Concentration 48

1305.3 Mixing Zone Authorization Application 48

1305.4 General Standards for Granting Interim Authorizations for 

Mixing Zones 

49

1305.5 Mixing Zones Boundaries 52

1305.6 Additional Standards for Granting Interim Authorizations 

for Mixing Zones

52

1305.7 Period to Grant Interim Authorizations for Mixing Zones 52

1305.8 Effectiveness of Interim Mixing Zone Authorization 52

1305.9 Calibration and Validation of Mathematical Models Used 

to Define a Mixing Zone

52

1305.10 Requirements for Granting Final Mixing Zones 

Authorizations

53

1305.11 Effectiveness of Final Authorizations of Mixing Zones 54

1305.12 Renewal of Mixing Zone Authorizations 54

1305.13 Revocation of Interim Authorizations or Final 

Authorizations of Mixing Zones

54

1305.14 Procedure for Revoking Mixing Zone Authorizations 55

1305.15 Submerged Outfall and Diffuser Requirements 55

1305.16 Compliance Plans 55

RULE 1306 GENERAL PROVISIONS 56

1306.1 General Prohibitions 56

1306.2 Source Monitoring, Record Keeping, Reporting, Sampling 

and Testing Methods

57

1306.3 Discharge Data Available to the Public 58

1306.4 Malfunction of Equipment Report 58

1306.5 Emergency Plan 58

1306.6 Personnel and Water Pollution Control Equipment 59

1306.7 Minimum Treatment Required 59

1306.8 Standards for Substances at Concentrations Below the 

Detection Level

59
TABLE OF CONTENTS (Cont.)

iii

PAGE

1306.9 Toxicity Tests 60

1306.10 Site-Specific Water Quality Standards 60

1306.11 Water Quality Certificate 60

1306.12 Compliance Plan 61

RULE 1307 PENALTIES 63

RULE 1308 ADDITIONAL PROVISIONS 64

1308.1 Public Nuisance 64

1308.2 Conflictive or Contradictory Provisions 64

1308.3 Derogation 64

1308.4 Separability Clause 64

1308.5 Effectiveness 64

1308.6 Review and Amendments to this Regulation 64

RULE 1309 RESERVED 67

RULE 1310 WASTE LOAD ALLOCATION 68

1310.1 General 68

1310.2 WLA Applications 68

1310.3 Conditions for Waste Load Allocations 68

1310.4 Dissolved Oxygen WLA 71

1310.5 Allocations 71

1310.6 Reallocations 73

1310.7 Effectiveness of the WLA 73

1310.8 Revocation 73

1310.9 Procedure for Revoking WLA 74

1310.10 Cost Incurred by the Board Performing WLA 74

ATTACHMENT Puerto Rico Environmental Quality Board Anti-Degradation

Policy Implementation Procedure

A-1
1

RULE 1300 TITLE, LEGAL BASIS, DECLARATION OF GOALS AND 

PURPOSE, AND ANTI-DEGRADATION POLICY

1300.1 TITLE

This Regulation will be known as “Puerto Rico Water Quality Standards 

Regulation”.

1300.2 LEGAL BASIS

This Regulation is enacted in accordance with Law No. 416 approved on 

September 22, 2004, as amended, known as the Public Policy Environmental 

Act, and nullifies any previous provision, resolution, agreement or regulation of 

the Commonwealth of Puerto Rico on the same subject which may contradict 

this Regulation.

1300.3 DECLARATION OF GOALS AND PURPOSES

The Environmental Quality Board recognizes that the pollution of the waters is 

detrimental to public health and welfare, creates public nuisances, is harmful 

to wildlife, fish and other aquatic life, and impairs domestic, agricultural, 

industrial, recreational and other beneficial uses of the waters.

It is the goal of this Board, and this Regulation, to preserve, maintain and 

enhance the quality of the waters of Puerto Rico in such manner that they be 

compatible with the social and economic needs of the Commonwealth of 

Puerto Rico.

The purposes of this Regulation are: (1) designate the uses for which the 

quality of the water bodies of Puerto Rico shall be maintained and protected; 

(2) prescribe the water quality standards required to sustain the designated 

uses; (3) identify other rules and regulations applicable to sources of pollution 

that may affect the quality of the waters subject to this Regulation and (4) 

prescribe other measures necessary for achieving and maintaining the quality 

of the waters of Puerto Rico.

1300.4 ANTI-DEGRADATION POLICY

It is the policy of the Commonwealth of Puerto Rico to conserve and protect 

the existing and designated uses of the waters of Puerto Rico. The water 

quality necessary to protect the existing uses, including threatened and 

endangered species shall be maintained and protected.

In those water bodies where the quality exceeds levels necessary to support 

propagation of fish, shellfish, wildlife, desirable species, including threatened 

or endangered species and recreation in and on the water, that quality shall be 
2

maintained and protected. A lower water quality may be allowed when the 

Board determines, after full satisfaction of the governmental coordination and 

public participation requirements of the Board's Continuing Planning Process, 

that allowing lower water quality is necessary to accommodate important 

economic or social development in the immediate area where the waters are 

located. In allowing such lower water quality, the Board shall require a water 

quality level adequate to fully protect existing and designated uses. Further, 

the Board will require that:

(1) the highest statutory and regulatory requirements for all new and/or 

existing point sources be achieved, and

(2) the cost-effective and reasonable best management practices for non-point 

sources control be implemented.

In such places where high quality waters constitute an outstanding national 

resource, such as waters of El Yunque National Forest and State parks, 

wildlife refuges and waters of exceptional recreational or ecological value, that 

water quality shall be maintained and protected.

Where potential water quality impairment is associated with a thermal 

discharge this thermal discharge must comply with Section 316 of the Clean 

Water Act, as amended, 33 U.S.C. §1326. 

Refer to the Attachment for the Environmental Quality Board Anti-degradation 

Policy Implementation Procedure.
3

RULE 1301 DEFINITIONS AND ACRONYMS

1301.1 DEFINITIONS

Acute Effect

Organism response to a stimulus, detected during an acute toxicity test that comprises 

a stimulus of such severity that induces a quick adverse effect. In toxicity tests, an 

acute response is considered to occur in a period of 96 hours or less. An acute effect 

can take place through events that not necessarily involve the death of the organism.

Acute Toxicity Test

Toxicity Test designed to determine the concentration in which a response to a 

stimulus, such as a total effluent, specific substance or combinations of these, has 

sufficient severity to induce an adverse effect on a group of test organisms during a 

period of 96 hours or less; even if said effect is not necessarily the death of the 

organisms.

Acute Toxicity Units (TUa)

The reciprocal of the effluent concentration that causes 50% of the organisms to die in 

an acute toxicity test or induce a response halfway between the base line and maximum 

as defined by the following equation:

50 50

a

LC or EC

TU =

100

(The LC50 or EC50 is expressed as the percent (%) of effluent in the dilution water).

Agent

All the factors, including light and heat, which cause or could cause, induce or could 

induce, produce or could produce, influence or could influence, help or could help to 

cause variations or alterations in organisms or in the environment.

Adverse Effect

Refers to any human-induced change in the quality of a water body that may cause 

undesirable physiological reactions in humans, fish or other fauna or flora.

Applicable Rules and Regulations

See Rule 1306.1 (B).
4

Background Concentration

Existing biological, chemical or physical characteristics in a water body. For mixing 

zones, a point one hundred (100) meters up-stream from the limit of the mixing zone will 

be used for monitoring, or at the location approved by the Board by mutual agreement 

with the petitioner, based on the details of each individual case. The value of the 

background concentration will be determined according to the procedures established 

by the Mixing Zone and Bioassay Guidelines, approved by the Board.

Benthic Species

Organisms that inhabit on, over, or in the bottom of the water body, live adhered to the 

bottom or crawl over the bottom.

Best Engineering Practices

Use of the most effective procedures, methods, techniques, and/or equipment to 

efficiently attain the desired objective at a minimum economic, human, and 

environmental cost.

Best Management Practices (BMP)

The most effective practicable means of preventing or reducing the amount of pollution 

generated by non-point and point sources to a level more compatible to the water 

quality goals, including, but not limited to, structural and non-structural controls and 

operating and maintenance procedures.

Bioaccumulative Agent

Agent which is assimilated by organisms, but is not metabolized and shows an 

elimination rate much lower than its accumulation rate, so that its total content tends to 

increase during the life of the affected organisms.

Biochemical Oxygen Demand

The quantity of oxygen required for the biochemical oxidation of organic matter in a 

sample.

Biota

All living organisms.

Black Waters

Human or animal bodily wastes and water used for flushing and/or transport of such 

wastes.
5

Board 

The Environmental Quality Board of the Commonwealth of Puerto Rico, as created 

pursuant to Law No. 9 of June 18, 1970, as amended, and derogated by Law No. 416 of 

September 22, 2004, as amended. 

Carcinogenic Agent

Agent that produces metabolic alterations in cells, prompting their uncontrolled growth.

Chronic Effect

Organism response to a stimulus, detected during a chronic toxicity test that comprises 

a stimulus that lingers or continues for a relatively long period of time, which could be of 

the order of one-tenth of the life span of the organism used in the test. A chronic effect 

could imply lethality, growth rate reduction, reduced reproduction rate, etc.

Chronic Toxicity Test

Toxicity Test designed to determine the concentration in which a response to a 

stimulus, such as a total effluent, a specific substance, or combination of these, has 

sufficient severity to induce a long-term adverse effect on a group of test organisms. A 

chronic effect could be lethality, reduction of growth rate, reduction of reproduction rate, 

etc.

Chronic Toxic Unit (TUc)

The reciprocal of the effluent concentration that causes no observable effect on the test 

organisms by the end of the chronic exposure period, obtained during a chronic toxicity 

test, as defined by the following equation:

NOEC

TUc=

100

(The NOEC value should be expressed in terms of the percent (%) of the effluent in the 

dilution water).

Clean Water Act 

Federal Water Pollution Control Act, as amended, (33 U.S.C. 466 et seq.).

Closed Water Body

All surface water bodies, groundwater and coastal waters that are not open coastal 

waters.
6

Coastal Waters 

Marine waters within the jurisdiction of the United States of America and the 

Commonwealth of Puerto Rico, as established by Article 8 of the Puerto Rico Federal 

Relations Act of 1917, as amended, and shore waters which are subject to ebb and flow 

of the tides. These waters do not include Estuarine Waters as defined in this 

Regulation.

Coliform Group 

All the aerobic organisms and facultative anaerobic gram-negative, non-spore-forming 

rod-shaped bacteria, that ferment lactose broth with gas formation within 48 hrs at 35°C 

± 0.5°C, in accordance with Standard Methods.

Colloidal Substances 

Minute substances including, but not limited to, clay or other substances which do not 

settle out without the use of a flocculating agent.

Criteria Continuous Concentration (CCC)

EPA national water quality criteria recommendation for the highest instream 

concentration of a toxicant or an effluent to which organisms can be exposed indefinitely 

without causing an unacceptable effect. It is equal to:

CCC =1.0TUc

Criteria Maximum Concentration (CMC)

EPA national water quality criteria recommendation for the highest instream 

concentration of a toxicant or an effluent to which organisms can be exposed for a brief 

period of time without causing an acute effect. It is equal to:

CMC= 0.3TUa

Critical Initial Dilution

Minimum dilution to be determined by means of the use of a mathematical model to be 

approved by the Board, and according to the procedures described in Mixing Zone and 

Bioassay Guidelines, approved by the Board.

Design Flow 

The critical flow used for steady state waste load allocation.
7

Designated Uses

Refers to those uses specified in this Regulation for each water body or segment 

whether or not these uses are being attained.

Desirable Species 

Species indigenous to the area or introduced to the area because of ecological or 

commercial value.

Diffuser

Structure which is connected to or is part of a submerged outfall provided with ports and 

whose function is to reduce the diameter of the outfall in order to increase the effluent 

exit velocity and obtain a better dilution in the receiving water body.

Dilution

Dilution is the reduction of the concentration of a substance by mixing it with ambient 

waters, and is defined by the following equations:

a. Volumetric Dilution:

e

e d

V

V +V

D=

where; D = Dilution 

Ve = Effluent volume

Vd = Dilution volume (receiving water body)

b. Flow Dilution:

e

e d

Q

Q +Q

D=

where; D = Dilution

Qe = Effluent flow 

Qd = Dilution flow (receiving water body)

c. Concentration Dilution:

a

e a

C C

C C

D =

where; D = Dilution

Ca = Background concentration of the pollutant
8

Ce = Concentration of the pollutant in the effluent

C = Final concentration of the pollutant after dilution

Dilution shall be determined according to the procedures described in Mixing Zone and 

Bioassay Guidelines approved by the Board.

Direct Contact Recreation 

See Primary Contact.

Direct Discharge 

Introduction of pollutants onto or into a water body by a point source.

Discharge 

Any addition, release, leak, spill, leachate, seepage, pumping, pouring, dumping, 

spraying, emptying or emitting of a pollutant into or onto the ground or any water body 

as defined in this Regulation.

Discharge Length Scale

The square-root of the cross-sectional area of any port in an outfall.

Dissolved Oxygen 

The amount of oxygen that is dissolved in water. It also, refers to the amount of oxygen 

available for biochemical activity in a water body.

Domestic Wastes 

Any liquid, gaseous, or solid waste or any combination of these generated as a result of 

satisfying the basic human and animal needs. 

Drainage Area 

That area in a horizontal plane, determined by a topographic divide from which surface 

runoff from precipitation drains by gravity into a water body above a specified point. 

Dye Test

Tests which are performed by injecting dyes into any point of a discharge to a water 

body, to determine the origin, the direction of the flow and the intermediate or final fate. 
9

e – Euler’s Number

2.71828 11 lim

n

n n

Numbere

Ecological Community 

Group of organisms dominated by one species or a specific group of species. The 

ecological community derives its name from that of the dominant species, such as coral 

reefs and mangroves.

EC50

A point estimate of the toxicant concentration that would cause an observable adverse 

effect (such as death, immobilization or serious incapacitation) in 50% of the test 

organisms.

Ecological Value

Refers to the existing interrelations between water body, fauna and flora that result in 

the continuity, stability and permanence of the ecological community.

Effect Concentration (EC)

A point estimate of the toxicant concentration that would cause an observable adverse 

effect (such as death, immobilization or serious incapacitation) in a given percentage of 

the test organisms.

Effluent 

Discharge of used waters, sanitary wastes, other wastewaters, or any liquid substances 

treated or untreated, proceeding from sanitary treatment plants, industrial wastewater 

treatment plants, manufacturing processes, storage tanks, ponds, sewers or any water 

pollution source.

Emergency Plan 

The document that details the equipment, workforce, procedures and steps to prevent, 

control and provide adequate countermeasures to spills of pollutants, such as, but not 

limited to, oil, hazardous substances and process waters.

Emergency Plan of the Commonwealth of Puerto Rico

The plan adopted by the Commonwealth of Puerto Rico that establishes the policies 

and structures for the government management of emergencies or disasters. This plan 

prescribes the phases of the emergencies and the disasters: prevention, preparation, 

response, mitigation and recovery. This plan covers all kind of incidents and risks.
10

Enduring Water Body

Water body which has a 7 day 2 year low flow greater than zero, even in the absence of 

any contribution that may occur from a discharge.

Enterococcus

The group of fecal streptococcus that excludes S. bovis and S. equinus, in accordance 

with Standard Methods.

Environmental Protection Agency (EPA)

The Environmental Protection Agency of the United States of America. 

Equitable Allowable Concentration (EAC)

A waste load allocation (WLA) method that allocates equal effluent concentrations of a 

substance x to each point source that discharges to the receiving water body in which 

the WLA is performed.

Estuary

That portion of the mouth or lower course of a river, stream, canal or lagoon, in which 

the fresh water meets the sea water and is subject to the ebb and flow of the tides.

Estuarine Waters 

See Estuary.

Eutrophic Conditions

Presence of high concentrations of nutrients causing excessive growth of algae and 

other aquatic plants in the water body.

Existing Uses

Those uses actually attained in the water body, on or after November 28, 1975, whether 

or not they are included in this Regulation.

Fecal Coliform 

The portion of the coliform group found in the intestinal tract of homoiothermic (warm 

blooded) animals and used as indicator of the potential presence of pathogenic 

organisms. This group of organisms is capable of producing gas from lactose broth in a 

suitable culture medium within 24 hours at 44.5°C ± 0.5°C. 
11

Flocculating Agent 

Chemical agent, which enhances the agglomeration of suspended solids in a liquid.

FORM WLA-01

Form required by the Board to present a waste load allocation application.

Frequency Curve

As used in this Regulation, the term refers to a graph plotted on log probability paper, 

representing the lowest mean flow of 7 consecutive days against the probability, using 

the procedures described in Appendix C of the Environmental Quality Board Waste 

Load Allocation Guidelines.

Gray Waters

Liquid and solid wastes from kitchens, bathrooms and water-using appliances except 

those that release or contain black waters.

Ground Waters 

Sub-surface waters present at or beneath the water table, including waters in caves and 

caverns when the presence of water results from the manifestation of the characteristics 

of the saturated zone beneath the water table. 

Habitat

The place where a population (e.g. human, animal, plant, microorganisms) lives and 

reproduces and its surroundings both living and non-living.

Harmonic Mean Flow (HMF)

The number of daily flow measurements (n) divided by the sum of the reciprocals of the 

flows (Q). That is, it is the reciprocal of the mean of reciprocals.

n

i Qi

n

HMF

1

1

Hazardous Solid Waste

Any solid waste designated as hazardous by the Board and as defined by the 

Regulation for the Management of Non-Hazardous Solid Wastes of the Commonwealth 

of Puerto Rico.
12

Hazardous Substances

Any substance designated as hazardous under 40 CFR Part 116, pursuant to Section 

311 of the Clean Water Act, or as defined by the Regulation for the Management of 

Non-Hazardous Solid Wastes of the Commonwealth of Puerto Rico.

Hydrologically-Based Design Flow (xQy)

Expressed as x-day average low flow whose return period is y-years. For example, 4Q3

is the four (4) days low flow that is exceeded once every three (3) years. Other xQy

values commonly encountered are: 1Q10, 4Q3, 30Q5, 7Q5, and 7Q10.

Hypothesis Testing

Statistical technique for determining whether a tested concentration is statistically 

different from the control. For example, Dunnett’s test. Endpoints determined from 

hypothesis testing are NOEC and LOEC.

Immediate vicinity of a discharge

Stream distance required to achieve complete mixing of a discharge.

Indirect Contact Recreation 

See Secondary Contact.

Indirect Discharge 

Discharge of pollutants, into a publicly owned treatment plant which discharges to a 

water body. 

Intermittent Stream

Watercourse where flow, other than from a discharge, occurs only during and following 

a period of a rainfall within its drainage area.

LC50 

The concentration of effluent, specific substances or combination of these that is lethal 

to 50% of test organisms exposed during a specific period in a toxicity test.

Leachate 

Liquid that has percolated through or drained from solid wastes and that contains 

soluble, partially soluble, suspended, or miscible materials, or components removed 

from such solid waste. 
13

Lethal Concentration (LC) 

The effluent concentration, specific substances or combinations of these, that is lethal to 

a given percent of the test organisms exposed during a specific period in a toxicity test. 

In the case of effluents the concentration is expressed in terms of percent dilution.

Ln Hardness 

The natural logarithm of the numerical value of hardness (as calcium carbonate in mg/L) 

of the water body.

Load or Loading

An amount of matter or thermal energy that is introduced into a receiving water body; to 

introduce matter or thermal energy into a receiving water body; may be either humaninduced (pollutant loading) or natural (natural background loading).

Local Water Depth

The depth at the point where the diffuser of an outfall is located under low tide 

conditions, for ocean outfalls; or low flow conditions, for surface water discharges.

Lowest Observed Effect Concentration (LOEC)

The lowest concentration of an effluent or toxicant that results in adverse effects on the 

test organisms. That is, where the values for the observed endpoints are statistically 

different from the control.

Maximum Allowable Effluent Concentration (MAEC)

Maximum effluent concentration of a substance x that is allocated to a point source.

Maximum Daily Load Allowable (MDLA)

Maximum load that can be allocated to point sources without causing a violation to the 

water quality standards.

Maximum Requested Effluent Concentration (MREC)

Maximum effluent concentration requested by a point source for a substance x.

Methylene Blue Active Substances (MBAS)

Refers to substances identified as anionic surfactants in accordance with Standard 

Methods (Method 512 B).
14

Mixing Zone

Tridimensional space in a receiving water body where the discharge is diluted with 

surrounding waters, which has been defined according to Rule 1305 of this Regulation. 

Applicable water quality standards, the CCC and the CMC are met at the boundary of 

the mixing zone.

Mixing Zone and Bioassay Guidelines

The most recent version of the technical guidelines developed and approved by the 

Board, which describe procedures, methods, models, techniques and organisms to be 

used to calculate the initial dilution; perform chronic and acute toxicity tests; to collect 

field data, or to establish the natural background concentration value, as required to 

verify compliance with inherent mixing zone conditions. These Guidelines are based on 

the following EPA publication: "Technical Support Document for Water Quality Based 

Toxics Control" and “Users Guide to the Conduct and Interpretation of Complex Effluent 

Toxicity Tests at Estuarine/Marine Sites". The guidelines will be revised, as necessary, 

in accordance with updated versions of these documents or other documents released 

by EPA, which directly impact the guidelines in effect at the time of publication of the 

final document.

Mutagenic Agent

Agent that induces genetic variations due to drastic changes in the organization of the 

genes in a chromosome.

Natural Background Concentration

The biological, physical and chemical characteristics existing in a water body that is not 

affected by point or non-point sources, as determined by field studies whose content 

and extension shall be defined according to Mixing Zone and Bioassay Guidelines, and 

according to the agreements between the Board and the petitioner, based upon the 

details of each case when problems arise in the implementation of said Guidelines.

Natural Causes

Refers to chemical, biological, geological or any other conditions existing at specific 

sites, not resulting from, or as a consequence of, human intervention.

No Observed Effect Concentration (NOEC)

The highest tested concentration of an effluent or a toxicant at which no adverse effects 

are observed on the aquatic test organisms at a specific time of observation. 

Determined using Hypothesis Testing.
15

Non-conservative Pollutant

A pollutant that is not persistent and is subject to decay or transformation.

Non-persistent Pesticides 

Those pesticides, which do not satisfy the definition of persistent pesticides.

Non-point Source 

Any source other than point source, as defined in this Regulation.

Non-point Source Loads (NPSL)

The portion of a receiving water body's total allowable pollutant load that is attributed to 

existing or future non-point sources and/or to natural background sources of pollution.

Objectionable Odor

Those considered in this manner in accordance to the procedure and requirements of 

the Air Pollution Control Regulation. The odor emitted by trees, shrubs, plants, flowers, 

grass, domestic gardening, and agricultural processes and the use of fertilizers (except 

for the use of sugarcane wastes), will not be considered objectionable.

Open Coastal Waters

All the coastal waters, except bays and estuaries, with formations that significantly 

mitigate the direct impact of the waves on the shore.

Outfall

Pipe or conduit, which conveys an effluent to a receiving water body.

Passageway 

A continuous stretch where water characteristics are affected only by natural conditions 

in such a manner that the free movement, flow or continuous drifting of biota is always 

possible.

Pathogenic Organism

Any microorganism, virus or bacteria that may cause disease.
16

Pelagic Species

Organisms that have the ability of self locomotion and can overcome the currents. 

These organisms can be found anywhere in the water column, near the surface, the 

bottom or at any point between the surface and the bottom.

Persistent Agent

An agent, which degrades or decomposes slowly, biologically or chemically, in the 

natural environment.

Persistent Pesticides

Pesticides not easily degradable under natural conditions and which initial concentration 

remains relatively unchanged for periods longer than 96 hours.

Person 

Any juridical or natural person; any agency, department, board, public or quasi-public 

corporation, municipality of the Commonwealth of Puerto Rico or the Government of the 

United States of America, any association, corporation, cooperative, trust, partnership, 

or group of persons.

Planktonic Species

Marine organisms that mainly inhabit the surface of the water body. Their main 

characteristic is that they cannot overcome the currents even if they have self 

locomotion.

Point of Discharge

Point where the effluent is discharged, treated or untreated, before mixing with the 

receiving waters.

Point Source

Any discernible source, confined and discrete conveyance, including, but not limited to: 

any pipe, ditch, channel, tunnel, trench, conduit, well, discrete fissure, container, rolling 

stock or any other mobile vehicles (such as mobile homes or mobile cafeterias), 

concentrated animal feeding operations, or vessel or other floating craft, from which 

pollutants are or may be discharged.

Pollutant 

Any matter introduced into the environment that includes but is not limited to: dredge 

spoil, refuse, solid waste, incinerator residue, filter backwash, gray waters, black waters, 
17

wastewaters, sludge, munitions, chemical materials, biological materials, radioactive 

materials, heat, debris, wrecked or discarded equipment, rock, sand, industrial, 

municipal, domestic, animal or agricultural waste, or any substance and/or material, 

including sediments and other substances induced by man, carried by stormwater 

runoff.

Pollution 

The presence of one or more pollutants in levels that result in the non attainment of the 

specified designated uses for a given water body.

Pollution Source

Any source, activity, building, structure, facility or vessel generating, emitting, 

discharging, storing or transporting pollutants.

Port

Orifice of the diffuser.

Primary Contact

Any recreational activity, including swimming or other uses in which there is required 

prolonged and direct contact of the human body with the water involving considerable 

likelihood of ingestion in quantities sufficient to pose a significant health hazard or in 

which there is complete immersion of sensitive organs such as eyes, nose and ears.

Priority Pollutant

Refers to pollutants identified by the EPA in accordance with Section 307(a) of the 

Clean Water Act, as amended.

Propagation and Preservation of Desirable Species

This refers to the reproduction and continuance of species of flora and fauna associated 

with water bodies and which have ecologic importance and/or commercial value, 

whether individually or as part of an ecological community.

Public Nuisance

Anything which is injurious to health, or indecent, or offensive to the senses, or an 

obstruction to free use of property, so as to interfere with the comfortable enjoyment of 

life or property, or that it will hinder the well-being of the whole local community, or a 

large number of persons, or that illegally it will obstruct the free transit, in the used from, 

for any lake, river, bay, current, channel or navigable basin, or for any park, square, 

street, public highway and similar others, it constitute a public nuisance that gives place 
18

to an action in accordance with Article 277 of the Code of Civil Indictment of 1933, as 

amended.

Public Policy Environmental Act

Law No. 9 of June 18, 1970, as amended, and derogated by Law No. 416 of September 

22, 2004, as amended.

Quality Assurance Project Plan (QAPP)

A document describing in comprehensive detail the necessary quality assurance, quality 

control, and other technical activities that must be implemented to ensure that the result 

of the work performed will satisfy the stated performance criteria.

Receiving Waters 

See Receiving Water Body.

Receiving Water Body 

Any water body, as defined in this Regulation, or segment, portion or part of such water 

body onto or into which a discharge is made.

Recharge Area 

That portion of the drainage area, as defined in this Regulation, in which water enters 

an aquifer system, as result of rainfall infiltration or seepage from surface waters.

Refuse 

All waste material, including but not limited to, garbage, rubbish, incinerator residues, 

street sweeping, dead animals, and animal wastes.

Reserve (R)

Portion of the maximum daily allowable load reserved as an allowance for economic 

development and population growth.

Sampling Point

Point determined by the Board to evaluate compliance with permits, orders, 

authorizations or applicable water quality standards. In cases concerning NPDES 

permits, the sampling point may be determined by EPA or the Board.
19

Sanitary Waste

See Domestic Waste.

Secondary Contact

Any recreational activity such as fishing or other use in which human body contact with 

the water is indirect and sensitive organs such as eyes, nose and ears are not 

immersed.

Secondary Treatment

Treatment of sewage using biological processes to such a degree that the effluent 

quality meets the requirements of 40 CFR Part 133, as revised. 

Sequentially

Refers to the manner in which the representative series of samples is taken to 

determine the geometric mean. The sampling interval used for each sample in the 

representative series should be uniform for each series. Example: A series of samples 

taken at hourly intervals, daily intervals, or weekly intervals.

Seven Day Low Flow

Refers to the flow at a given recurrence interval taken from a frequency curve of annual 

values of the lowest mean flow for 7 consecutive days. For example, 7 day low flow, 

"n"-years (7Qn) refers to the low flow in 7 days at a recurrence interval of "n" years.

Sewage 

Sanitary wastes from humans and animals coming from households, commercial 

establishments, industries, public and private buildings, farms and others places that 

are discharged to a wastewater treatment plant.

Significant Public Health Risk

Contingency of a direct or indirect injury to human well being. The hazard of the 

occurrence of an acute or chronic effect on the health including, but not limited to, 

diseases, epidemics, mutations or deformations in humans.

Solid Wastes

Any waste designated as solid by the Board and as defined by the Regulation for the 

Management of Non-Hazardous Solid Wastes of the Commonwealth of Puerto Rico.
20

Source 

See Pollution Source.

Standard Methods 

Refers to the most recently approved edition under 40 CFR Part 136 for each applicable 

parameter of the "Standard Methods for the Examination of Water and Wastewater".

Stormwater Runoff

For the purposes of this Regulation the term refers to flows of water, resulting from 

rainfall, that enter the water bodies.

Stratified Lake

In its simplest form refers to a lake with layers of water at different temperatures and 

densities. The upper layer with relatively high temperatures and low densities in 

comparison with the lower layer which has lower temperatures and higher densities. 

Between these two layers is a transitional layer with a marked temperature and density 

gradient that prevents the mixing of the upper and lower layers.

Submerged Outfall

Pipe or conduit, which conveys the effluent to the point of discharge in a receiving water 

body. The pipe or conduit is located at the bottom of the water body.

Surface Waters 

Any natural or artificial water source including all streams, lakes, reservoirs, inland 

watercourse and waterways, springs, irrigation systems, drainage systems, intermittent 

streams and all other inland water bodies or accumulated waters. For the purpose of 

this Regulation the term does not include coastal waters and estuarine waters as 

defined in this Regulation.

Surfactants

See Methylene Blue Active Substances (MBAS).

Synergistic Effect

Occurs when two (2) or more substances, which in the original state could be harmless, 

react to each other and cause a toxicity, which is greater than the sum of the individual 

toxicity of each substance.
21

Teratogenic Agent

Agent, which induces anomalies in the fetal development.

Thermal Discharge

Emission of heat or substances with heat, which temperature causes the receiving 

water body to exceed the temperature of 32.2°C or 90°F.

Topographic Divide

Line along the ground that separates the rainfall surface runoff between two different 

drainage areas.

Total Allowable Pollutant Load (TAPL)

Maximum amount of a pollutant (i.e. the sum of the individual point sources, the 

individual existing or future non-point sources, the natural background sources and the 

reserve) that a water body can receive and still meet the applicable water quality 

standards.

Total Coliform

See Coliform Group.

Toxic Substances

Those substances or combinations thereof, including disease causing agents, which 

after being discharged and by the exposure, ingestion, inhalation or assimilation by any 

organism, directly from the environment or indirectly by means of ingestion through the 

food chain; may cause, death, illness, abnormal behavior, cancer, genetic mutation, 

physiologic malfunctioning (including malfunction in reproduction), or physical 

deformations, in said organisms or their descendants based on the available information 

to the Board or to EPA.

Toxicity Test

Test to determine the acute or chronic response of living organisms to an effluent, 

specific substances or combination of these, using a representative organism approved 

by the Board and following the procedures described in the guidelines developed and 

approved by the Board for these purposes.

Waste Load Allocation (WLA)

The portion of a receiving water total allowable pollutant load (TAPL) that is allocated to 

one of its existing or future point sources of pollution.
22

Waste Load Allocation Guidelines (WLAG)

The most recent version of the technical guidelines developed and approved by the 

Board, which describe procedures, methods, techniques and other related matters to be 

used by the Board to perform waste load allocations.

Wastewaters

Waters containing dissolved, suspended, agglomerated, emulsified or floating 

substances or solid pollutants resulting from industrial, commercial, residential, 

agricultural, recreational or any other type of establishment or man induced activity.

Wastewater Treatment Facilities 

See Water Pollution Control Facilities or Equipment.

Water Body 

See Waters of Puerto Rico.

Water Pollutant Control Facilities or Equipment

Any process, equipment, device, and all appurtenances there to, used for eliminating, 

reducing, or controlling the discharge of any pollutant to the water. 

Water Quality Standards

The designated water body uses and classifications, the criteria to protect those uses, 

and the anti-degradation policy.

Water Table

The soil depth at which the pressure of the saturated zone is equal to atmospheric 

pressure.

Waters

See Waters of Puerto Rico.

Waters of Puerto Rico 

All coastal waters, surface waters, estuarine waters, ground waters and wetlands as 

defined in this Regulation.

Watershed 

See Drainage Area.
23

Wetlands

Areas inundated or saturated by coastal, surface or ground water at a frequency and 

duration sufficient to support, and under normal circumstances do support a prevalence 

of vegetation, typically adapted for life in saturated soil conditions.

1301.2 ACRONYMS

AWLA Application for a Waste Load Allocation

BMP Best Management Practices

BOD Biochemical Oxygen Demand

CCC Criteria Continuous Concentration

CFR Title 40 of the Code of Federal Regulations

CMC Criteria Maximum Concentration

EAC Equitable Allowable Concentration

EC Effect Concentration

EPA U. S. Environmental Protection Agency

HMF Harmonic Mean Flow

LC Lethal Concentration

LOEC Lowest Observed Effect Concentration

MAEC Maximum Allowable Effluent Concentration

MBAS Methylene Blue Active Substances

MDLA Maximum Daily Load Allowable

MREC Maximum Requested Effluent Concentration

NOEC No Observed Effect Concentration

NPDES National Pollutant Elimination System

NPSL Non-Point Source Loads

QAPP Quality Assurance Project Plan

R Reserve

TAPL Total Allowable Pollutant Load

TUa Acute Toxic Units

TUc Chronic Toxic Units

WLA Waste Load Allocation

WLAG Waste Load Allocation Guidelines

xQy Hydrologically-Based Design Flow
24

RULE 1302 CLASSIFICATION OF THE WATERS OF PUERTO RICO

ACCORDING TO THE DESIGNATED USES TO BE PROTECTED

1302.1 COASTAL WATERS AND ESTUARINE WATERS

A. Class SA

Class SA includes bioluminiscent lagoons and bays such as La Parguera 

and Monsio José on the Southern Coast, Bahía de Mosquito in Vieques, 

and any other coastal or estuarine waters of exceptional quality or high 

ecological value or recreational which may be designated by the Board, 

through Resolution, requiring this classification for protection of the 

waters. Rule 1303.2 (A) (2) of this Regulation will also apply to the waters 

500 meters (0.31 mile) seaward of the physical and geographical limits of 

the water bodies under this classification.

B. Class SB

Class SB includes the coastal and estuarine waters not classified as Class 

SA or SC under Rules 1302.1 (A) and (C) of this Regulation. Class SB 

also includes lagoons not classified under any other class. This 

classification will apply from the zone subject to the ebb and flow of tides 

(mean sea level) up to 500 meters (0.31 mile) seaward from said zone. 

Beyond this limit, the next less restrictive classification will apply to a 

maximum of 10.35 miles (16,656.71 meters) seaward.

1. Shellfish growing areas:

Those areas that may be designated by the Board, through Resolution, as 

shellfish growing areas. The existing water quality regulations established 

by both the U.S. Public Health Service and the Department of Health of 

the Commonwealth of Puerto Rico shall be applied to this classification. 

This classification will apply 100 meters (0.062 mile) beyond the physical 

and geographical areas limiting the shellfish growing areas.

C. Class SC

Class SC includes the segments of coastal and estuarine waters identified 

below. The classification of these waters shall be applied from the zone 

subject to the ebb and flow of tides (mean sea level) to 10.35 miles 

seaward.

1. Mayagüez Bay – From Punta Guanajibo to Punta Algarrobo.

2. Yabucoa Port.
25

3. Guayanilla and Tallaboa Bays – From Cayo Parguera to Punta 

Verraco.

4. Ponce Port – From Punta Carenero to Punta Cuchara.

5. San Juan Port – From the mouth of Río Bayamón to Punta El Morro.

1302.2 SURFACE WATERS

A. Class SD

All surface waters are classified SD, except those classified SE in 

accordance with Rule 1302.2 (B).

B. Class SE

Laguna Tortuguero, Laguna Cartagena and any other surface water body 

of exceptional quality or high ecological or recreational value which may 

be designated by the Board, through Resolution, requiring this 

classification for protection of the waters.

1302.3 GROUND WATERS

A. Class SG

This classification includes all ground waters as defined in this Regulation.
26

RULE 1303 WATER QUALITY STANDARDS AND USE CLASSIFICATIONS 

TO BE PROTECTED IN THE WATERS OF PUERTO RICO

Pursuant to the intent of this Regulation, the following water quality standards and use 

classifications are promulgated for the protection of the uses assigned to the 

classifications of the coastal, surface, estuarine, wetlands, and ground waters of the

Commonwealth of Puerto Rico.

The following water quality standards shall apply at all times, except in:

A. Surface waters during periods when their flows are less than the average 

minimum seven day low flow which occurs once in any two consecutive 

years.

B. Waters within mixing zones authorized by the Board pursuant to Rule 

1305 of this Regulation.

C. Surface, coastal, estuarine and ground waters where it is demonstrated, to 

the satisfaction of the Board, that the natural background concentration of 

the water body exceeds the established water quality standards. In those 

cases the applicable standard will be the natural background 

concentration.

D. Surface waters in the immediate vicinity of a discharge for which a waste 

load allocation has been authorized by the Board pursuant to Rule 1310 of 

this Regulation.

E. Intermittent streams when the conditions of Rule 1304.3 of this Regulation 

are met.

1303.1 WATER QUALITY STANDARDS

All waters shall meet generally accepted aesthetic requirements. These 

waters shall, except as specifically noted, meet the following water quality 

standards:

A. Solids and Other Matter

The waters of Puerto Rico shall not contain floating debris, scum or other 

floating materials attributable to discharges in amounts sufficient to be 

unsightly or deleterious to the existing or designated uses of the water 

body.
27

B. Color, Odor, Taste and Turbidity

The waters of Puerto Rico shall be free from color, odor, taste or turbidity 

attributable to discharges in such a degree as to create a nuisance to the 

enjoyment of the existing or designated uses of the water body.

C. Radioactive Materials

In the waters of Puerto Rico the concentration of Radium-226 and 

Strontium-90 shall not exceed 3 and 10 picocuries per liter respectively. 

In the absence of Strontium-90 and alpha emitters, the gross beta 

concentrations shall not exceed 1,000 picocuries per liter.

D. Temperature

1. Except by natural causes, no heat may be added to the waters of 

Puerto Rico, which would cause the temperature of any site to exceed 

90°F or 32.2°C.

2. No thermal discharge or combination of thermal discharges into or onto 

the surface, estuarine and coastal waters shall be injurious to aquatic 

life or the culture or propagation of a balanced indigenous population 

there of nor in anyway affect the designated uses.

3. In stratified lakes, thermal discharges shall be confined to the 

epilimnetic layer.

4. No thermal discharge or combination of thermal discharges shall be 

made to ground waters. 

E. Suspended, Colloidal or Settleable Solids

Solids from wastewater sources shall not cause deposition in or be 

deleterious to the existing or designated uses of the water body.

F. Biochemical Oxygen Demand

The allowable level of biochemical oxygen demand of wastewater sources 

will be determined on a case by case basis, depending on the assimilative 

capacity of the receiving water body. Such determination will be 

performed to assure compliance with the dissolved oxygen standard 

applicable to the receiving water body.
28

G. Asbestos

In order to assure for the protection of human health from the potential 

carcinogenic effects of exposure to asbestos, the waters of Puerto Rico 

shall not exceed 7 MFL (million fibers per liter) of asbestos, except when 

established that such presence is due to the natural occurrence of 

geologic deposits of asbestiform minerals.

H. Oil and Grease

The waters of Puerto Rico shall be substantially free from floating nonpetroleum oils and greases as well as petroleum derived oils and greases.

I. Substances in Toxic Concentrations and Synergistic Toxic Effects

The waters of Puerto Rico shall not contain any substance at such 

concentration which, either alone or as result of synergistic effects with 

other substances is toxic or produces undesirable physiological responses 

in human, fish or other fauna or flora.

In Rules 1303.1 (I) (1), 1303.1 (I) (2), 1303.1 (I) (3), 1303.1 (I) (4), and 

1303.1 (I) (5) are identified specific substances for which numeric water 

quality standards have been established.

1. Specific Water Quality Standards for Inorganic Substances

The maximum allowable concentration of these specific substances in 

coastal, surface, estuarine and ground waters shall not exceed the 

following at any time:

Substance Classes SB and SC 

(μg/L)

ClassSD

(μg/L)

Class SGa

(μg/L)

+,& Antimony (Sb) 640 (HH) 5.6 (HH) 5.6 (HH)

+,*,

&

Arsenic (As) 36 (AL) 10 (DW) 10 (DW)

+,%

, & Cadmium (Cd) 8.85 (AL) Note 1 (AL) 5.0 (DW)

+ Cyanide (Free CN) 1.0 (AL) 5.2 (AL) 200 (DW)

+, & Copper (Cu) 3.73 (AL) Note 3 (AL) 1,300 (HH)

+, & Chromium III (Cr+3) --- Note 2 (AL) ---

+, & Chromium VI (Cr+6) 50.35 (AL) 11.43 (AL) ---

& Chromium (Cr) --- --- 100 (DW)

Fluoride (F) --- 4,000 (DW) 4,000 (DW)

+, & Mercury (Hg) 0.051 (HH) 0.050 (HH) 0.050 (HH)

+, & Nickel (Ni) 8.28 (AL) Note 4 (AL) 610 (HH)

Nitrate + Nitrite

(as N) --- 10,000 (DW) 10,000 (DW)
29

Substance Classes SB and SC 

(μg/L)

ClassSD

(μg/L)

Class SGa

(μg/L)

Nitrite (as N) --- --- 1,000 (DW)

Nitrogen

(NO3, NO2, NH3)

5,000 --- ---

+, & Silver (Ag) 2.24 (AL) Note 5 (AL) ---

+,%

, & Lead (Pb) 8.52 (AL) Note 6 (AL) 15.0 (DW)

+, & Selenium (Se) 71.14 (AL) 5.0 (AL) 50.0 (DW)

Sulfide (S) 

(undissociated H2S) 2.0 (AL) 2.0 (AL) ---

+, & Thallium (Tl) 0.47 (HH) 0.24 (HH) 0.24 (HH)

+, & Zinc (Zn) 85.62 (AL) Note 7 (AL) ---

Note 1 Concentration in μg/L must not exceed the numerical value given by 

0.7409 ln Hardness 4.719

e

Note 2 Concentration in μg/L must not exceed the numerical value given by 

0.8190 ln Hardness +0.6848

e

Note 3 Concentration in μg/L must not exceed the numerical value given by 

0.8545 ln Hardness 1.702

e

Note 4 Concentration in μg/L must not exceed the numerical value given by 

0.8460 ln Hardness +0.0584

e

Note 5 Concentration in μg/L must not exceed the numerical value given by 

1.72 ln Hardness 6.59

e

Note 6 Concentration in μg/L must not exceed the numerical value given by 

1.273 ln Hardness 4.705

e

Note 7 Concentration in μg/L must not exceed the numerical value given by 

0.8473 ln Hardness +0.884

e

Hardness (as CaCO3 in mg/L) of the water body.

Identification codes for the applicability of standards to uses. These codes include designated and existing uses.

AL = Protection of the water body for the propagation and preservation of aquatic species or species dependent on the 

water body.

DW = Protection of the water body for use as source of drinking water supply.

HH = Protection of the water body or aquatic life for reasons of human health.

* = Identifies a substance that may be a carcinogen.

+ = Identifies a priority pollutant.

% = In cases where the surface water body is used as a source of drinking water supply, the water quality standard for the 

indicated substance shall not exceed the drinking water standard upstream from the water intake.

& = Numbers represent a total recoverable value.

a = For the protection of ground waters with the potential to be used or that are used as source of drinking water supply, the 

applicable water quality standard is the Drinking Water (DW) or Human Health (HH) criteria. For those ground waters that 

flow into other water bodies, the applicable water quality standard for ground waters is the most stringent criteria resulting 

from the comparison between the standard applicable to the classification of the water body into which it flows and the DW 

or HH criteria applicable to ground waters.

2. Specific Water Quality Standards for Pesticides

a. Organochlorides and Other Persistent Pesticides

Organochlorides and other persistent pesticides residues in 

surface, ground, estuarine and coastal waters shall not exceed 

1/100 of the 96 hr LC50 of species approved by the Board. In the 

specific case of the following, the concentration shall not exceed 

the value listed below:
30

Substance Classes SB and 

SC (μg/L)

Class SD 

(μg/L)

Class SGa

(μg/L)

+, * Aldrin 0.0005 (HH) 0.00049 (HH) 0.00049 (HH)

+, * alpha-BHC 0.049 (HH) 0.026 (HH) 0.026 (HH)

+, * beta-BHC 0.17 (HH) 0.091 (HH) 0.091 (HH)

+, * Chlordane 0.004 (AL) 0.0043 (AL) 0.0080 (HH)

+, * 4, 4’- DDT and Metabolites 0.001 (AL) 0.001 (AL) 0.0022 (HH)

+, * Dieldrin 0.00054 (HH) 0.00052 (HH) 0.00052 (HH)

+ Endosulfan 0.0087 (AL) 0.056 (AL) 62 (HH)

+ Endosulfan Sulfate 89 (HH) 62 (HH) 62 (HH)

+ Endrin 0.0023 (AL) 0.036 (AL) 0.059 (HH)

+ Endrin Aldehyde 0.30 (HH) 0.29 (HH) 0.29 (HH)

+, * Heptachlor 0.00079 (HH) 0.00079 (HH) 0.00079 (HH)

+ Heptachlor Epoxide 0.0036 (AL) 0.0038 (AL) 0.2 (DW)

+ Lindane (Gamma BHC) 0.16 (AL) 0.2 (DW) 0.2 (DW)

Methoxychlor 0.03 (AL) 0.03 (AL) 40.0 (DW)

Mirex 0.001 (AL) 0.001 (AL) ---

+, * Pentachlorophenol 7.9 (AL) 1.0 (DW) 1.0 (DW)

+, * Toxaphene 0.0002 (AL) 0.0002 (AL) 0.0028 (HH)

Identification codes for the applicability of standards to uses. These codes include designated and existing uses.

AL = Protection of the water body for the propagation and preservation of aquatic species or species dependent on the 

water body.

DW = Protection of the water body for use as source of drinking water supply.

HH = Protection of the water body or aquatic life for reasons of human health.

* = Identifies a substance that may be a carcinogen.

+ = Identifies a priority pollutant.

a = For the protection of ground waters with the potential to be used or that are used as source of drinking water supply, the 

applicable water quality standard is the Drinking Water (DW) or Human Health (HH) criteria. For those ground waters that 

flow into other water bodies, the applicable water quality standard for ground waters is the most stringent criteria resulting 

from the comparison between the standard applicable to the classification of the water body into which it flows and the DW 

or HH criteria applicable to ground waters.

b. Sulfurous Organothiophosphorus and Other Non-persistent 

Pesticides

Sulfurous Organothiophosphorus and other non-persistent 

pesticides residues in surface, ground, estuarine and coastal 

waters shall not exceed 1/10 of the 96-hr LC50 of species approved 

by the Board. In the specific case of the following pesticides, the 

concentration shall not exceed the values listed below:

Substance Classes SB and SC 

(μg/L)

Class SD 

(μg/L)

Class SGa

(μg/L)

2,4,5 – TP (Silvex) --- 10.0 (HH) 10.0 (HH)

* 2,4 – D --- 70 (DW) 70 (DW)

Azinphos – Methyl 0.01 (AL) 0.01 (AL) ---

Chloropyrifos 0.0056 (AL) 0.041 (AL) ---
31

Substance Classes SB and SC 

(μg/L)

Class SD 

(μg/L)

Class SGa

(μg/L)

Coumaphos 0.010 (AL) 0.010 (AL) ---

Demeton 0.10 (AL) 0.10 (AL) ---

Fenthion 0.40 (AL) 0.40 (AL) ---

Malathion 0.10 (AL) 0.10 (AL) ---

Naled 0.40 (AL) 0.40 (AL) ---

Parathion --- 0.013 (AL) ---

Identification codes for the applicability of standards to uses. These codes include designated and existing uses.

AL = Protection of the water body for the propagation and preservation of aquatic species or species dependent on the 

water body.

DW = Protection of the water body for use as source of drinking water supply.

HH = Protection of the water body or aquatic life for reasons of human health.

* = Identifies a substance that may be a carcinogen.

a = For the protection of ground waters with the potential to be used or that are used as source of drinking water supply, the 

applicable water quality standard is the Drinking Water (DW) or Human Health (HH) criteria. For those ground waters that 

flow into other water bodies, the applicable water quality standard for ground waters is the most stringent criteria resulting 

from the comparison between the standard applicable to the classification of the water body into which it flows and the DW 

or HH criteria applicable to ground waters.

3. Specific Standards for Non-Pesticide Organic Substances and 

Carbon Tetrachloride

These specific substances shall not exceed the maximum allowable 

concentration, at any time in, coastal, surface, estuarine and 

ground waters.

Substance Classes SB and SC 

(μg/L)

Class SD 

(μg/L)

Class SGa

(μg/L)

+ 1,1-Dichloroethylene 7,100 (HH) 7.0 (DW) 7.0 (DW)

+ 1,1,1-Trichloroethane --- 200.0 (DW) 200.0 (DW)

+ 1,2-Dichlorobenzene

(o-Dichlorobenzene)

1,300 (HH) 420 (HH) 420 (HH)

+, * 1,2-Dichloroethane 370 (HH) 3.8 (HH) 3.8 (HH)

+ 1,3-Dichlorobenzene

(m-Dichlorobenzene)

960 (HH) 320 (HH) 320 (HH)

+ 1,4-Dichlorobenzene

(p-Dichlorobenzene)

190 (HH) 63 (HH) 63 (HH)

+, * 2,3,7,8-TCDD (Dioxin) 5.1 x 10-8(HH) 5.0 x 10-8

(HH)

5.0 x 10-8

(HH)

+, * 2,4,6-Trichlorophenol 24 (HH) 14 (HH) 14 (HH)

+ 2,4-Dichlorophenol 290 (HH) 77 (HH) 77 (HH)

+ 2,4-Dimethylphenol 850 (HH) 380 (HH) 380 (HH)

+ 2-Chlorophenol 150 (HH) 81 (HH) 81 (HH)

+ 2-Methyl-4,6-Dinitrophenol 280 (HH) 13 (HH) 13 (HH)

+ 2,4-Dinitrophenol 5,300 (HH) 69 (HH) 69 (HH)

+, * Carbon Tetrachloride 16 (HH) 2.3 (HH) 2.3 (HH)

+ Phenol 1,700,000 (HH) 21,000 (HH) 21,000 (HH)
32

Substance Classes SB and SC 

(μg/L)

Class SD 

(μg/L)

Class SGa

(μg/L)

+, * Polychlorinated Biphenyls 

(PCBs)

0.00064 (HH) 0.00064 (HH) 0.00064 

(HH)

+, * Tetrachloroethylene 33 (HH) 5.0 (DW) 5.0 (DW)

+, * Trichloroethylene 300 (HH) 5.0 (DW) 5.0 (DW)

+, * Vinyl Chloride 24 (HH) 0.25 (HH) 0.25 (HH)

Identification codes for the applicability of standards to uses. These codes include designated and existing uses.

DW = Protection of the water body for use as source of drinking water supply.

HH = Protection of the water body or aquatic life for reasons of human health.

* = Identifies a substance that may be a carcinogen.

+ = Identifies a priority pollutant.

a = For the protection of ground waters with the potential to be used or that are used as source of drinking water supply, the 

applicable water quality standard is the Drinking Water (DW) or Human Health (HH) criteria. For those ground waters that 

flow into other water bodies, the applicable water quality standard for ground waters is the most stringent criteria resulting 

from the comparison between the standard applicable to the classification of the water body into which it flows and the DW 

or HH criteria applicable to ground waters.

4. Specific Water Quality Standards for Volatile Organic Substances

These specific substances shall not exceed the maximum allowable 

concentration, at any time in coastal, surface, estuarine and ground 

waters.

Substance Classes SB and SC

(μg/L)

Class SD

(μg/L)

Class SGa

(μg/L)

+ 1,1,2-Trichloroethane 160 (HH) 5.0 (DW) 5.0 (DW)

+, * 1,1,2,2-Tetrachloroethane 40 (HH) 1.7 (HH) 1.7 (HH)

+ 1,2,4-Trichlorobenzene 70 (HH) 35 (HH) 35 (HH)

+, * 1,2-Dichloropropane 150 (HH) 5.0 (HH) 5.0 (DW)

+, * 1,3-Dichloropropylene 210 (HH) 3.4 (HH) 3.4 (HH)

+, * Acrylonitrile 2.5 (HH) 0.51 (HH) 0.51 (HH)

+ Acrolein 290 (HH) 190 (HH) 190 (HH)

+, * Benzene 510 (HH) 5.0 (DW) 5.0 (DW)

+, * Bromoform 1,400 (HH) 43 (HH) 43 (HH)

+ Chlorobenzene 1,600 (HH) 100 (DW) 100 (DW)

+, * Chlorodibromomethane 130 (HH) 4.0 (HH) 4.0 (HH)

+, * Chloroform 4,700 (HH) 57 (HH) 57 (HH)

+, * Dichlorobromomethane 170 (HH) 5.5 (HH) 5.5 (HH)

+ Ethylbenzene 2,100 (HH) 530 (HH) 530 (HH)

+ Methyl Bromide 1,500 (HH) 47 (HH) 47 (HH)

+, * Methylene Chloride 5,900 (HH) 46 (HH) 46 (HH)
33

Identification codes for the applicability of standards to uses. These codes include designated and existing uses.

DW = Protection of the water body for use as source of drinking water supply.

HH = Protection of the water body or aquatic life for reasons of human health.

* = Identifies a substance that may be a carcinogen.

+ = Identifies a priority pollutant.

a = For the protection of ground waters with the potential to be used or that are used as source of drinking water supply, the 

applicable water quality standard is the Drinking Water (DW) or Human Health (HH) criteria. For those ground waters that 

flow into other water bodies, the applicable water quality standard for ground waters is the most stringent criteria resulting 

from the comparison between the standard applicable to the classification of the water body into which it flows and the DW 

or HH criteria applicable to ground waters.

5. Specific Water Quality Standards for Semi-Volatile Organic 

Substances

These specific substances shall not exceed the maximum allowable 

concentration, at any time in coastal, surface, estuarine and ground 

waters.

Substance Classes SB and SC

(μg/L)

Class SD

(μg/L)

Class SGa

(μg/L)

+, * 1,2-Diphenylhydrazine 2.0 (HH) 0.36 (HH) 0.36 (HH)

+ 1,2-Trans-Dichloroethylene 10,000 (HH) 100 (DW) 100 (DW)

+ 2–Chloronapthalene 1,600 (HH) 1,000 (HH) 1,000 (HH)

+, * 2,4-Dinitrotoluene 34 (HH) 1.1 (HH) 1.1 (HH)

+, * 3,3-Dichlorobenzidine 0.28 (HH) 0.21 (HH) 0.21 (HH)

+ Acenapthene 990 (HH) 670 (HH) 670 (HH)

+ Anthracene 40,000 (HH) 8,300 (HH) 8,300 (HH)

+, * Benzidine 0.0020 (HH) 0.00086 

(HH)

0.00086 

(HH)

+, * Benzo(a)Anthracene 0.18 (HH) 0.038 (HH) 0.038 (HH)

+, * Benzo(a)Pyrene 0.18 (HH) 0.038 (HH) 0.038 (HH)

+, * Benzo(b)Fluoranthene 0.18 (HH) 0.038 (HH) 0.038 (HH)

+, * Benzo(k)Fluoranthene 0.18 (HH) 0.038 (HH) 0.038 (HH)

+, * Bis(2-Chloroethyl)Ether 5.3 (HH) 0.30 (HH) 0.30 (HH)

+, * Bis(2-Chloroisopropyl)Ether 65,000 (HH) 1,400 (HH) 1,400 (HH)

+, * Bis(2-Ethylhexyl)Phthalatex22 (HH) 12 (HH) 12 (HH)

+, * Butylbenzyl Phthalatew1,900 (HH) 1,500 (HH) 1,500 (HH)

+, * Chrysene 0.18 (HH) 0.038 (HH) 0.038 (HH)

+, * Dibenzo(a,h)Anthracene 0.18 (HH) 0.038 (HH) 0.038 (HH)

+ Diethyl Phthalatew44,000 (HH) 17,000 

(HH)

17,000 

(HH)

+ Dimethyl Phthalatew1,100,000 (HH) 270,000 

(HH)

270,000 

(HH)

+ Di-n Buthyl Phthalatew4,500 (HH) 2,000 (HH) 2,000 (HH)

+ Fluoranthane 140 (HH) 130 (HH) 130 (HH)

+ Fluorene 5,300 (HH) 1,100 (HH) 1,100 (HH)
34

Substance Classes SB and SC

(μg/L)

Class SD

(μg/L)

Class SGa

(μg/L)

+, * Hexachlorobenzene 0.0029 (HH) 0.0028 

(HH)

0.0028 

(HH)

+, * Hexachlorobutadiene 180 (HH) 4.4 (HH) 4.4 (HH)

+ Hexachlorocyclopentadiene 1,100 (HH) 40 (HH) 40 (HH)

+, * Hexachloroethane 33 (HH) 14 (HH) 14 (HH)

+, * Ideno(1,2,3–cd)Pyrene 0.18 (HH) 0.038 (HH) 0.038 (HH)

+, * Isophorone 9,600 (HH) 350 (HH) 350 (HH)

+, * N–Nitrosodimethylamine 30 (HH) 0.0069 

(HH)

0.0069 

(HH)

+, * N–Nitrosodi-n-Propylamine 5.1 (HH) 0.050 (HH) 0.050 (HH)

+, * N–Nitrosodiphenylamine 60 (HH) 33 (HH) 33 (HH)

+ Nitrobenzene 690 (HH) 17 (HH) 17 (HH)

+ Pyrene 4,000 (HH) 830 (HH) 830 (HH)

+ Toluene 15,000 (HH) 1,000 (DW) 1,000 (DW)

Identification codes for the applicability of standards to uses. These codes include designated and existing uses.

DW = Protection of the water body for use as source of drinking water supply.

HH = Protection of the water body or aquatic life for reasons of human health.

* = Identifies a substance that may be a carcinogen.

+ = Identifies a priority pollutant.

a = For the protection of ground waters with the potential to be used or that are used as source of drinking water supply, the 

applicable water quality standard is the Drinking Water (DW) or Human Health (HH) criteria. For those ground waters that 

flow into other water bodies, the applicable water quality standard for ground waters is the most stringent criteria resulting 

from the comparison between the standard applicable to the classification of the water body into which it flows and the DW 

or HH criteria applicable to ground waters.

1303.2 USE CLASSIFICATIONS AND WATER QUALITY STANDARDS FOR 

SPECIFIC CLASSIFICATIONS

A. Class SA

1. Usages and Description

Coastal waters and estuarine waters of high quality or exceptional 

ecological or recreational value whose existing conditions shall not be 

altered, except by natural causes, in order to preserve its natural 

characteristics.

2. Standards

The concentration of any parameter, whether or not considered in this 

Rule, shall not be altered, except by natural causes. Substances 

reactive with methylene blue shall not be present.
35

B. Class SB

1. Usages and Description

Coastal waters and estuarine waters intended for use in primary and 

secondary contact recreation, and for propagation and preservation of 

desirable species, including threatened or endangered species.

2. Standards

a. Dissolved Oxygen

Shall not contain less than 5 mg/L, except when this value is 

depressed due to natural causes.

b. Coliforms

The fecal coliform geometric mean of a series of representative 

samples (at least five samples) of the waters taken sequentially 

shall not exceed 200 colonies/100 mL, and not more than 20 

percent of the samples shall exceed 400 colonies/100 mL.

c. Enterococci

The enterococci density, in terms of geometric mean of at least five 

representative samples taken sequentially, shall not exceed 35 

colonies/100 mL. No single sample should exceed the upper 

confidence limit of 75% using 0.7 as the log standard deviation, 

until sufficient site data exist to establish a site-specific log standard 

deviation.

d. pH

In no case the pH will lie outside the range of 7.3 to 8.5, standard 

pH units, except when it is altered by natural causes.

e. Color

Shall not be altered except by natural causes.

f. Turbidity

Shall not exceed 10 nephelometric turbidity units (NTU), except by 

natural causes.
36

g. Taste or Odor Producing Substances

Shall not be present in amounts that will interfere with primary 

contact recreation, or will render any undesirable taste or odor 

to edible aquatic life.

h. Sulfates

For SB estuarine waters, sulfates shall not exceed 2,800 mg/L.

i. Surfactants as Methylene blue active substances (MBAS)

Shall not exceed 500 μg/L.

C. Class SC

1. Usages and Description

Coastal waters intended for primary contact recreation use from the 

zone subject to ebb and flow of tides (mean sea level) to 3 miles 

seaward, and secondary contact recreation from 3 miles seaward to 

10.35 miles seaward, and for the propagation and preservation of 

desirable species, including threatened or endangered species.

2. Standards

a. Dissolved Oxygen

Shall contain not less than 4 mg/L, except when this value is 

depressed due to natural causes

b. Coliforms

From the zone subject to ebb and flow of tides (mean sea level) to 

3 miles seaward, the coliform geometric mean of a series of 

representative samples (at least five samples) of the waters taken 

sequentially shall not exceed 200 colonies/100 mL of fecal 

coliforms. Not more than 20 percent of the samples shall exceed 

400 colonies/100 mL of fecal coliforms.

From 3 miles seaward to 10.35 miles seaward, the coliform 

geometric mean of a series of representative samples (at least five 

samples) of the waters taken sequentially shall not exceed 2,000 

colonies/100 mL of fecal coliforms. Not more than 20 percent of 

the samples shall exceed 4,000 colonies/100 mL of fecal coliforms.
37

c. Enterococci

From the zone subject to ebb and flow of tides (mean sea level) to 

3 miles seaward, the enterococci density in terms of geometric 

mean of at least five representative samples taken sequentially 

shall not exceed 35 colonies/100 mL. No single sample should 

exceed the upper confidence limit of 75% using 0.7 as the log 

standard deviation until sufficient site data exist to establish a sitespecific log standard deviation.

d. pH

In no case the pH will lie outside of 7.3 to 8.5, standard pH units, 

except when it is altered by natural causes.

e. Color

Shall not be altered by other than natural causes.

f. Turbidity

Shall not exceed 10 nephelometric turbidity units (NTU), except by 

natural causes.

g. Taste or Odor Producing substances

Shall contain none in amounts that will render any underable taste 

or odor to edible aquatic life.

h. Sulfates

For estuarine waters classified SC, sulfates shall not exceed 2,800 

mg/L.

i. Surfactants as Methylene blue active substances (MBAS)

Shall not exceed 500 ug/L.

D. Class SD

1. Usages and Description

Surface waters intended for use as a raw source of public water 

supply, propagation and preservation of desirable species, including 

threatened or endangered species, as well as primary and secondary 

contact recreation. Primary contact recreation is precluded in any
38

stream or segment that does not comply with Rule 1302.2 (D) (2) (l) 

until such stream or segment meets the goal of the referred section.

2. Standards

a. Dissolved Oxygen

Shall contain not less than 5.0 mg/L except when this value is 

depressed due to natural causes.

b. Coliforms

The coliform geometric mean of a series of representative samples 

(at least five samples) of the waters taken sequentially shall not 

exceed 10,000 colonies/100 mL of total coliform or 200 

colonies/100 mL of fecal coliforms. Not more than 20 percent of 

the samples shall exceed 400 colonies/100 mL of fecal coliforms.

c. pH

Shall always lie between 6.0 and 9.0 standard pH units, except 

when the value of pH falls outside this range due to natural causes.

d. Color

Shall not exceed 15 units according to the colorimetric platinumcobalt standard, except by natural causes. In cases where the 

water body normally exceeds this value, the mechanism provided 

under Rule 1306.10 of this Regulation may be used to develop sitespecific criteria.

e. Turbidity

Shall not exceed 50 nephelometric turbidity units (NTU), except by 

natural causes.

f. Total Dissolved Solids

Shall not exceed 500 mg/L, except by natural causes.

g. Taste or Odor Producing Substances

Shall not be present in amounts that will interfere with the use for 

potable water supply, or will render any undesirable taste or odor to 

edible aquatic life.
39

h. Total Phosphorus

Total phosphorus shall not exceed 1 ppm (mg/L), in surface water 

bodies upstream from reservoirs, in segments of surface water 

bodies with drinking water intakes or estuarine waters except when 

it is demonstrated to the satisfaction of the Board that a higher 

value of total phosphorus in combination with prevailing nitrogen 

derived nutrients will not contribute to eutrophic conditions in the 

water body.

i. Surfactants as Methylene blue active substances (MBAS)

Shall not exceed 100 μg/L.

j. Sulfates

Shall not exceed 250 mg/L, except by natural causes.

k. Chlorides

Shall not exceed 250 mg/L, except by natural causes.

l. Other Pathogenic Organisms

These waters shall be free from other pathogenic organisms 

different to coliforms.

m. Total Ammonia

Total ammonia shall not exceed 1 mg/L upstream from the points 

given by the coordinates of the following segments: 

Río Cibuco 18°21'13" 66°20'07"

Río Hondo 18°26'13" 66°09'36"

Río Guaynabo 18°22'32" 66°07'59"

Río Bayamón 18°24'39" 66°09'09"

Río Piedras 18°24'34" 66°04'10"

Quebrada Blasina 18°23'27" 65°58'28"

Río Caguitas 18°15'11" 66°01'26"

Río Bairoa 18°15'28" 66°02'13"

Río Chico 17°59'16" 66°00'18"

Río Coamo 18°03'52" 66°22'10"

Río Guayanilla 18°00'50" 66°47'04"

Río Guanajibo 18°07'18" 67°03'56"
40

E. Class SE

1. Usages and Description

Surface waters and wetlands of exceptional ecological value, whose 

existing conditions should not be altered in order to preserve its natural 

characteristics.

2. Standards

The concentration of any parameter, whether or not considered in this 

Rule, shall not be altered, except by natural causes. Substances 

reactive with methylene blue shall not be present.

F. Class SG

1. Usages and Description

Ground waters intended for use as source of drinking water supply and 

agricultural uses including irrigation. Also, included under this class 

are those ground waters that flow into coastal, surface, and estuarine 

waters and wetlands as defined in this Regulation.

2. Standards

a. Dissolved Gases

The composition, combination and concentration of dissolved 

gases shall not be altered except by natural causes.

b. Coliforms

Fecal coliforms shall not exceed 0 colonies/100 mL in any sample 

by the MF (Membrane Filter) method.

c. pH

Shall not be altered except by natural causes.

d. Color

Shall not be altered except by natural causes.

e. Turbidity

Shall not be altered except by natural causes.
41

f. Total Dissolved Solids

Shall not be altered except by natural causes. Here the term natural 

causes do not include salt water intrusion, unless this results from 

severe drought conditions.

g. Taste or Odor Producing Substances

Shall not be altered except by natural causes.

h. Surfactants as Methylene blue active substances (MBAS)

Shall not be present.
42

RULE 1304 INTERMITTENT STREAMS

1304.1 GENERAL

Point sources may be relieved from complying with the applicable provisions 

of Rule 1303 of this Regulation, if the applicant, demonstrates to the 

satisfaction of the Board, that the source is discharging into an intermittent 

stream and that the conditions specified elsewhere in this Rule are met.

1304.2 APPLICATION FOR RELIEF

A. Content of the Application

The application shall contain the following:

1. Evidence, to the satisfaction of the Board, that the water course is 

intermittent, including an evaluation of the physical and hydrological 

characteristics of the stream bed. Such evidence must be certified by 

an engineer licensed to practice in Puerto Rico, a geologist, a 

hydrologist or a hydrogeologist.

2. A map which displays:

a. The intermittent stream under consideration, including the name of 

such body where available;

b. The location of all existing, proposed and anticipated discharges in 

the affected watershed;

c. The location of the nearest downstream enduring water body; 

d. The location of water supply intakes for humans and farm animals 

in the intermittent stream, if any, and the intakes downstream from 

the intermittent stream; 

e. The location of wetlands adjacent or associated with the 

intermittent stream and the nearest downstream watercourse not 

found to be an intermittent stream; 

f. The location of karst or water recharge areas within the intermittent 

stream. If no karst or water recharge areas are located within the 

intermittent stream, a certification to that effect will be required from 

a hydrologist, geologist or hydrogeologist.

g. Non-point source activities in the immediate watershed of the 

intermittent stream.
43

h. Itemization of existing recreational uses. If no existing recreational 

uses are given to the intermittent stream, a certification to that 

effect will be required from the Department of Sports and 

Recreation and from the Mayor(s) of the municipality(ies) where the 

intermittent stream is located.

4. Biological study identifying the indigenous aquatic communities in the 

intermittent stream.

5. Determine effluent toxicity in accordance with the most recent version 

of the "Mixing Zone and Bioassay Guidelines" approved by the Board.

B. Authorized Signature

All applications shall be signed by the owner or operator, or in case of a 

corporation, by the President of the Corporation, or the Vice President 

directly responsible to the President, the highest ranking corporate official 

with offices in Puerto Rico, a duly authorized representative, responsible 

for the overall operation or regulated activity who presents a document in 

which such authority is delegated to that representative, in the case of 

other non-corporate entities, by an official of equivalent authority.

C. Certification of the Application for Relief

Any person signing the application shall make the following certification:

"I certify under penalty of law that I have personally examined and I am 

familiar with the information submitted in this document and all 

attachments and that, based on my inquiry with those individuals 

immediately responsible for obtaining the information, I understand that 

the information is true, accurate and complete. I am aware that there are 

significant penalties for submitting false information, including the 

possibility of fine and imprisonment."

1304.3 REQUIREMENTS FOR GRANTING RELIEF

No relief from complying with the applicable provisions of Rule 1303 of this 

Regulation shall be granted, unless the following requirements are met:

A. The intermittent stream shall not contain substances or materials, 

including floating debris, oil, scum and other matter attributable to point 

sources, in amounts or concentrations that:

1. Form objectionable deposits;

2. Create nuisances;
44

3. Produce objectionable color, taste, or odor;

4. Produce undesirable aquatic life or result in a dominance of nuisance 

species;

5. Cause injuries to, be hazardous to, or produce adverse physiological 

responses in humans, animals or plants;

6. Interfere with or impair existing uses downstream of the water body.

B. The intermittent stream shall contain no less than 3.0 mg/L of dissolved 

oxygen.

C. Domestic wastewater treatment systems shall provide at least secondary 

treatment and non-domestic wastewater treatment systems shall provide 

the best available control technology, unless higher levels of treatment are 

necessary, as determined by the Board, to:

1. Protect the existing instream uses of the receiving water body and of 

downstream waters;

2. Protect ground water or recharge areas;

3. Comply with Rule 1304.3 (A) and

4. Prevent a public health hazard.

D. Applicable water quality standards are met at the point where the 

intermittent stream meets the nearest downstream enduring water body.

E. The intermittent stream is not used as a source of water supply for 

humans or farm animals.

F. The existing capacities of the water body, determined to be intermittent, to 

support the propagation and maintenance of indigenous aquatic 

communities will not be adversely affected by the proposed discharge.

G. The existing recreational uses will not be adversely affected.

H. The discharge will not adversely affect the ground water quality.

I. The discharge will not adversely affect wetlands adjacent to or associated 

with the intermittent stream.

J. The discharge will not create a potential health hazard or harmful 

conditions.
45

K. The applicant complies with the applicable provisions concerning public 

participation contained in Rules 1304.5 and 1304.6.

L. The discharge shall not contain substances at concentrations, which are 

carcinogenic, mutagenic, teratogenic or otherwise hazardous. Discharges 

of these substances will be required to meet the applicable criteria in 

Rules 1303.1 (I) (1), 1303.1 (I) (2), 1303.1 (I) (3), 1303.1 (I) (4), and 

1303.1 (I) (5) at the end-of-pipe when the flow of the stream is composed 

entirely of the effluent.

1304.4 PRELIMINARY DETERMINATIONS

For every complete application received, the Board shall prepare Preliminary 

Determinations summarizing the principal facts, stating the Board's 

preliminary determination, briefly describing the basis for such determination 

and including any other relevant information.

1304.5 PUBLIC NOTICE AND OPPORTUNITY FOR PUBLIC HEARING

A. Requirements for the Public Notice

A public notice shall be published in two (2) newspapers of wide 

circulation in Puerto Rico informing the Board's intention to grant or deny 

relief from the provisions of Rule 1303 of this Regulation. Such notice shall 

also:

1. Identify the intermittent stream under consideration, if it has a name, 

and a description of its location;

2. Identify the nearest downstream watercourse which has been 

determined to be an enduring water body;

3. Identify the applicant and description of proposed discharge(s) into the 

intermittent stream;

4. Inform the public and interested parties that comments can be 

submitted to the Board and/or public hearings can be requested within 

thirty (30) days after publication of the notices;

5. Include the place and times in which the Preliminary Determination and 

other relevant documents are available for public inspection;

6. Include any other relevant information determined by the Board.
46

B. Cost of the Public Notice

The applicant shall pay to the Board the cost of publication of the notices 

before printing, or assume the responsibility to publish the notices. In the 

latter case the notices shall comply with the specifications of the Board.

1304.6 PUBLIC HEARINGS

A. Requirements for Public Hearings

The Board may hold public hearings at its own discretion or if:

1. There is a significant degree of public interest, as determined by the 

Board;

2. One or more of the aspects involved in the Board's decision may be 

clarified in the hearing.

B. Content of the Public Notice

If the Board decides to hold public hearings, a notice shall be published in 

two (2) newspapers of wide circulation in Puerto Rico. Such notice shall 

specify:

1. The day(s), the time(s) and the place(s) of the public hearing(s).

2. The information required in Rule 1304.5 (A), except item 4.

3. Include any other pertinent information specified by the Board.

C. Requirements to Publish Public Notice

The public notices shall be published at least thirty (30) days prior to the 

hearing.

D. Cost of Public Notice

The applicant shall pay to the Board the cost of publication of the notices 

before printing, or assume responsibility to publish the notices. In the latter 

case the notices shall comply with the specifications of the Board.

1304.7 FINAL DETERMINATION

If public hearings are not held, the Board shall emit the Final Determination 

after considering the comments received within the thirty (30) days after 

publication of the notices informing the public of the Preliminary 
47

Determinations. If public hearings are held, the Board shall emit the Final 

Determination after considering all the comments received within the thirty 

(30) days after publication of the notices informing the public of the 

Preliminary Determinations, the comments received during the public 

hearings and the report from the hearing panel.

1304.8 DURATION OF RELIEF

Relief shall initially be granted for a one (1) year period. If warranted, the 

renewal of relief shall be effective for a fixed period established by the Board, 

not to exceed five (5) years.

1304.9 REVOCATION OF RELIEF

The Board may revoke a relief granted under Rule 1304 for the following 

causes:

A. Non-compliance with any condition of the relief;

B. The applicant's failure, in the application or during the processing of the 

relief, to disclose fully all relevant facts, or the permittee's 

misrepresentation of any relevant fact at any time;

C. A determination that the discharge endangers human health or the 

environment.

1304.10 MONITORING REQUIREMENTS

In those cases where the Board grants a relief, the applicant must perform 

samplings to determine the chemical, physical and biological characteristics 

of the discharge, the intermittent stream, the nearest downstream enduring 

water body and any other water body, as it is determined by the Board. The 

nature, extension and frequency of these samplings will be established by the 

Board on a case by case basis.
48

RULE 1305 MIXING ZONES

1305.1 GENERAL

Authorizations for mixing zone shall not be transferable and do not imply a 

property right of any kind or exclusive privilege, nor do they authorize any 

harm to persons or property or the invasion of others private rights, or the 

infringement of federal or state laws or regulations.

1305.2 NATURAL BACKGROUND CONCENTRATION

If the petitioner demonstrates to the satisfaction of the Board, through 

extensive sampling and field investigations, that the natural background 

concentration of the receiving waters exceed one or more of the water quality 

standards set forth for the corresponding classification, the Board may allow 

the parameters in the discharge to be equal to or less than the natural 

background concentrations.

1305.3 MIXING ZONE AUTHORIZATION APPLICATION

Each application for a mixing zone shall include the following:

A. Evidence that the project has complied with Article 4 (B) (3) of the Law 

416 of September 22, 2004, Environmental Public Policy Act, as amended 

(previously Article 4-C, of the derogated Law No. 9 of June 18, 1970, 

Environmental Public Policy Act, as amended), if the application is related 

to a new or modified discharge; a new or modified submerged outfall; or a 

new or modified discharge channel, by the submittal of the corresponding 

environmental document.

B. Physical, chemical and biological characterization of the discharge and of 

the receiving waters at the site in which the background concentration is 

measured, as specified in the most recent version of the Mixing Zone and 

Bioassay Guidelines approved by the Board. This characterization shall 

include the results of toxicity tests using organisms approved by the Board 

and following the methodology described in said guidelines.

C. Existing discharge flow or proposed discharge flow for new or modified 

discharges.

D. Concentration of each one of the substances or parameters that do not 

comply with the applicable water quality standards at the point of 

discharge, after using best practicable technology (BPT), as defined by 

EPA, for their control.
49

E. Detailed hydraulic design calculations for the proposed discharge system 

demonstrating that the best engineering practices (BEP) have been used 

for obtaining the required dilution in the least possible tridimensional 

space.

F. Description of each mathematical model utilized to determined the critical 

initial dilution for open coastal waters and dilution for closed water bodies; 

used to define the mixing zone and the corresponding calculations, and/or 

the field studies where the oceanographic data, measurements of the 

physical/chemical parameters around the existing discharges and the 

associated ecological studies demonstrate the extension and effects of the 

mixing zone.

G. Diagram showing the proposed mixing zone and indicating the 

coordinates of the points that define the boundaries of the mixing zone.

H. Proposed method to validate and calibrate (if necessary) each 

mathematical model, including a monitoring plan and a Quality Assurance 

Project Plan (QAPP) that includes field sampling and laboratory analysis.

I. Proposed method for the maintenance of the discharge system.

J. Discussion of agreements reached with the Board on how the applicable 

provisions of Rule 1305 of this Regulation will be complied with.

1305.4 GENERAL STANDARDS FOR GRANTING INTERIM AUTHORIZATIONS 

FOR MIXING ZONES

An interim authorization for a mixing zone will be granted when the petitioner 

has submitted an application in which it is demonstrated, to the satisfaction of 

the Board, the following:

A. Compliance with Article 4 (B) (3) of the Law 416 of September 22, 2004, 

Environmental Public Policy Act, as amended (previously Article 4-C, of 

the derogated Law No. 9 of June 18, 1970, Environmental Public Policy 

Act, as amended), when the application is related to a new or modified 

discharge, new or modified submerged outfall, or a new or modified 

discharge channel.

B. The proposed discharge system constitutes the best engineering practices 

(BEP) to minimize the size of the tridimensional space of the mixing zone, 

maintaining the required dilution.

C. Solids in the discharge will not settle on the bottom of the receiving 

waters.
50

D. At the boundaries of the proposed mixing zone, after critical initial dilution 

for open coastal waters and after dilution for closed water bodies each one 

of the following requirements are met:

1. The concentration of pollutants or physical parameters, as defined in 

Rule 1305.5, do not exceed the applicable water quality standards.

2. The acute toxicity units measure in a acute toxicity test do not exceed 

the criteria maximum concentration (CMC).

3. The chronic toxicity units measure in a chronic toxicity test do not 

exceed the criteria continuous concentration units (CCC).

4. For fresh waters, and in coastal waters where the effluent is not 

discharged through a high rate diffuser, the CMC shall be reached in 

the most restrictive of the following conditions:

a. Ten percent (10%) of the distance from the point of the discharge to 

the mixing zone boundary.

b. A distance of fifty (50) times the discharge length scale in any 

spatial direction. This requirement, in the case of multiple ports 

diffusers, shall be met for each port using the discharge length 

scale of said port.

c. A distance of five (5) times the local water depth in any horizontal 

direction from any port discharge.

E. The discharge shall not cause the growth or propagation of organisms that 

negatively disturb the ecological equilibrium in areas adjacent to the 

mixing zone.

F. The mixing zone shall be located as to allow, at all times, passageways for 

the movement or drift of the biota. Also, the passageways shall comply 

with the following in the specific cases mentioned:

1. If the receiving water body is a closed water body, estuary, river or 

creek, the mixing zone shall be located close to the bank in such 

manner that the passageway allows the adequate and safe flow of free 

floating, swimming or drifting organisms, or organisms that have self 

propulsion.

2. If the receiving water body is an estuary, the surface area and volume 

of passageway shall be at least seventy five percent (75%) of the 

corresponding surface area of the volume of the receiving water body 

across each segment of the estuary.
51

3. If the receiving water body is a river or a creek, the surface area and 

the cross-sectional area of the downstream of this point shall be at 

least sixty-seven percent (67%) of the surface area and the crosssectional area of each segment of the river or creek.

4. If the receiving water body is a closed body of water, the sum of all 

mixing zone surface areas shall not exceed twenty percent (20%) of 

the surface area of the receiving body of water.

G. The mixing zone requested will not overlap with an adjacent mixing zone.

H. The control technology in accordance with Rule 1306.7, of this Regulation 

is being used or proposed.

I. The mixing zone shall be free of debris scum, floating oils, and any other 

substances which produce objectionable odors.

J. Each mathematical model used by the petitioner to define the mixing zone 

and inputs of said mathematical model were approved by the Board.

K. The mixing zone shall not be located in a recognized fish spawning or 

aquatic organism nursery area or habitat for threatened or endangered 

species.

L. The mixing zone shall not affect in any manner drinking water supply 

intakes or water intakes for livestock enterprises located less than one 

hundred (100) meters upstream, or five (5) kilometers downstream.

M. Except in the case of cooling waters, the mixing zone limits in coastal 

waters shall not be located at a distance less than one (1) kilometer from 

areas designated as public beaches, or classified as SA, and in every 

water body shall be restricted to avoid interferences with the designated 

uses of the receiving waters.

N. The proposed methodology to calibrate and validate each mathematical 

model used is acceptable to the Board.

O. The proposed method for maintaining in good working conditions the 

discharge system is acceptable to the Board.

P. The proposed method for defining the mixing zone boundaries is 

acceptable to the Board.

Q. Each proposed mixing zone complies with applicable requirements set 

forth in Rule 1305 of this Regulation.
52

1305.5 MIXING ZONE BOUNDARIES

The mixing zone boundaries shall be determined according to the procedures 

described in "Mixing Zone and Bioassays Guidelines" approved by the Board.

1305.6 ADDITIONAL STANDARDS FOR GRANTING INTERIM AUTHORIZATIONS

FOR MIXING ZONES

Interim authorizations for mixing zones shall be granted when the petitioner 

demonstrates to the satisfaction of the Board compliance with the 

requirements set forth in the "Mixing Zone and Bioassay Guidelines", 

approved by the Board.

1305.7 PERIOD TO GRANT INTERIM AUTHORIZATIONS FOR MIXING ZONES

Within sixty (60) days of the submittal of an approvable application, the Board 

shall make public their intention to issue or modify the Water Quality 

Certificate and to define an Interim Mixing Zone Authorization.

1305.8 EFFECTIVENESS OF INTERIM MIXING ZONE AUTHORIZATION

The interim mixing zone authorization shall go into effect after being 

incorporated into the NPDES permit, and it will be valid for a period not to 

exceed one and a half (11⁄2) years; or until the NPDES permit expires; or a 

date which the Board determines, based on the data submitted by the 

petitioner pursuant to the provisions of Rule 1305.9 or that the mixing 

zones(s) cannot be validated, whichever occurs first.

1305.9 CALIBRATION AND VALIDATION OF MATHEMATICAL MODELS USED TO 

DEFINE A MIXING ZONE

In the process of obtaining a mixing zone authorization, the petitioner shall 

submit to the Board information related to the following aspects:

A. Calibration

The petitioner shall calibrate those mathematical models that require 

calibration, as part of the process of granting an interim authorization for a 

mixing zone.

B. Monitoring Program for Validation

The petitioner shall implement a one (1) year monitoring program to obtain 

the necessary data required to validate each mathematical model during 

two (2) seasons (winter and summer). 
53

1. The monitoring program shall include as a minimum:

a. Continuous flow measurements.

b. Sampling of a frequency to be established by the Board on a case 

by case basis, at the following locations:

i. Effluent

ii. Station approved by the Board to determine the background 

concentration for each one of the substances for which a 

mixing zone is requested

iii. Stations approved by the Board at the boundaries of the 

mixing zone

c. Analysis of all parameters that prompted the mixing zone 

application and other parameters needed to run each 

corresponding mathematical model.

d. Current velocities at a frequency to be established by the Board on 

a case by case basis, if current velocities are an input to the 

mathematical model used to define the mixing zone.

C. Validation

The petitioner shall show that the model passes the validation test. This 

shall be done by means of a comparative analysis between the obtained 

values in the sampling program, against the values calculated by the 

model for corresponding points throughout the periphery of the mixing 

zone. The model in which the 90 percent of the calculated values are 

equal or less than the ones obtained through the sampling program shall 

be validated. In the case of Dissolved Oxygen, the model in which the 90 

percent of the calculated values are equal or greater than the ones 

obtained through the sampling program shall be validated. Since the field 

data are affected by variations in water currents, tides, etc., which vary as 

a function of time, the referred comparison shall be done considering the 

data obtained in real time or as close to it as possible.

1305.10 REQUIREMENTS FOR GRANTING FINAL MIXING ZONES 

AUTHORIZATIONS

A final mixing zone authorization will be issued if the mathematical model is 

validated as established in Rule 1305.9 of this Regulation.
54

1305.11 EFFECTIVENESS OF FINAL AUTHORIZATION OF MIXING ZONES

A final authorization of a mixing zone shall be valid for a period not to exceed 

five (5) years, but in no case will it exceed the expiration date of the NPDES 

permit.

1305.12 RENEWAL OF MIXING ZONE AUTHORIZATIONS

At least one hundred and eighty (180) days prior to the expiration date of a 

final mixing zone authorization, the person to whom the authorization was 

issued, shall submit a complete application for the renewal of the mixing zone 

authorization. The renewal application shall contain the information that has 

changed with respect to the information previously submitted in compliance 

with the specifications of Rule 1305.3, and a certification indicating that the 

remaining of the information has not changed.

1305.13 REVOCATION OF INTERIM AUTHORIZATIONS OR FINAL 

AUTHORIZATIONS OF MIXING ZONES

The Board may revoke an interim authorization or final authorization of a 

mixing zone for the following reasons:

A. The mathematical model used to define the mixing zone was not 

validated. The Board, upon request by the petitioner, can approve a 

Compliance Plan in which corrective actions are committed to take place 

within the shortest time possible to obtain the necessary validation. The 

Board can maintain in effect the Interim Authorization while the corrective 

actions incorporated in the mentioned plan are executed. 

B. The petitioner's failure to fully disclose all relevant facts in the 

authorization application or renewal, or the petitioner's misrepresentation 

of any relevant facts during the mixing zone evaluation or during the 

validation process.

C. Non-compliance with any applicable provision in Rule 1305 of this 

Regulation.

D. Changes in the conditions under which the mixing zone was approved, 

including, but not limited to discharge flow, effluent characteristics, and the 

discharge system, as originally approved by the Board.

E. There is an imminent threat to human health or the environment.
55

1305.14 PROCEDURE FOR REVOKING MIXING ZONE AUTHORIZATIONS

If there are reasons to revoke a mixing zone authorization as specified in Rule 

1305.11, the Board shall notify the person to whom the authorization was 

granted indicating the intention of revoking the authorization by means of a 

Show Cause Order. The procedures to follow are those specified in the 

Reglas de Procedimiento de Vistas Administrativas de la Junta de Calidad 

Ambiental. Notwithstanding the foregoing, the Board may immediately revoke 

a mixing zone authorization without previous notice, nor the opportunity of 

hearings if there is an imminent threat to human health or the environment.

1305.15 SUBMERGED OUTFALL AND DIFFUSER REQUIREMENTS

The submerged outfalls and the diffusers shall be designed, constructed and 

operated in accordance to best engineering practices. When the proposed 

discharge system incorporates said technology, the petitioner shall include in 

the mixing zone application, information regarding the following:

A. Length and diameter of the diffuser

B. Number, diameter and the diffuser ports distribution

C. Maximum and minimum exit velocities in the diffuser ports

D. Measures to avoid the intrusion of surrounding waters within the diffuser

E. The Froude number used for the design of the ports

F. Submerged outfall diameter and average value of the transversal area that 

will be full under normal operating conditions

G. Minimum and maximum design velocities for the submerged outfall flow

H. Any other design detail that could contribute to optimize the fast dilution of 

discharge

1305.16 COMPLIANCE PLANS

As requested by the petitioner, the Board may consider and approve 

Compliance Plans for existing discharges that do not comply with the 

requirements specified in this Regulation. Such plans shall indicate the way 

in which those discharges will achieve compliance with this Regulation, using 

the best engineering practices and within the shortest period of time, which 

will not exceed the NPDES permit expiration date, but under no 

circumstances shall exceed more than three (3) years.
56

RULE 1306 GENERAL PROVISIONS

1306.1 GENERAL PROHIBITIONS

A. Pollution of the Waters of Puerto Rico

No person shall cause or allow the pollution of the waters of Puerto Rico, 

as defined in Rule 1301 of this Regulation.

B. Discharge of Pollutants

No person shall cause or allow the discharge of any pollutant to the waters 

of Puerto Rico, in violation of Applicable Rules and Regulations.

1. These Applicable Rules and Regulations include the water quality 

standards and all other requirements established by this Regulation or 

by other laws or regulations of the Commonwealth of Puerto Rico, 

concerning the conservation and protection of the natural resources 

that may affect the quality of the water resources.

2. Moreover, such Applicable Rules and Regulations shall be deemed to 

prohibit any discharge that, in the judgment of the Board, prevents or 

interferes with the attainment or maintenance of applicable water 

quality standards established by this Regulation or by other laws or 

regulations of the Commonwealth of Puerto Rico.

C. No person shall cause or allow any discharge of contaminants for which:

1. this Board has not defined and approved a mixing zone in accordance 

with Rule 1305 of this Regulation; or

2. this Board has not performed a waste load allocation analysis in 

accordance with Rule 1310 of this Regulation; or

3. this Board has not approved an exemption of compliance with the 

requirements of Rule 1303 for discharge to intermittent streams in 

accordance with Rule 1304 of this Regulation; or

4. this Board has not approved a Compliance Plan in accordance with 

Rule 1306.12 of this Regulation; or

5. no effluent limits based on water quality where developed using any of 

the methods mentioned above or any other defensible method that is 

also acceptable by the Board.
57

1306.2 SOURCE MONITORING, RECORD KEEPING, REPORTING, SAMPLING 

AND TESTING METHODS

A. Monitoring, Records, and Reports

The Board may require the owner of any source, at the owner’s expense, 

to properly use and maintain any monitoring equipment, sample and 

measure the volume of discharges, sample the receiving waters, establish 

and maintain records, and make periodic reports as the Board shall 

prescribe.

B. Right of Entry

Representatives of the Board, properly identified shall have:

1. right to entry to, upon or through any premises or facilities in which a 

source is located or in which any records required to be maintained 

under this Regulation are located.

2. access to, inspect and copy any records required under this 

Regulation, inspect any monitoring equipment or method to determine 

its accuracy, and sample any discharge or receiving waters, which the 

owner is required to sample under this Regulation.

C. Sample Collection and Analysis

All sample collection, preservation, and analysis shall be carried out in 

accordance with those methods and procedures described in the 

"Standard Methods” as defined the term in this Regulation or the 40 CFR 

Part 136. All chemical analyses shall be certified by a chemist licensed to 

practice the profession in Puerto Rico. All bacteriological tests shall be 

certified by a medical technician licensed to practice the profession in 

Puerto Rico.

D. Certification of Records and Reports

All records and reports required pursuant to this Regulation shall be 

submitted together with a sworn statement or affidavit of the corporate 

president or of the highest ranking corporate officer with offices in Puerto 

Rico or of an equally responsible officer in the case of organizations other 

than corporations. Such sworn statement or affidavit can be signed by an 

officer previously authorized in writing by the responsible officer named 

above, and shall, in all cases, attest to the truth, correctness, and 

completeness of such records and reports.
58

E. Sampling and Testing Facilities

The Board may conduct tests of discharges of pollutants to the waters of 

Puerto Rico from any source. Upon request of the Board, the person 

responsible for the source to be tested, shall provide such safe and proper 

sampling and testing facilities, (but not including instrument and testing 

devices, except when required pursuant to other provisions of this 

Regulation, orders, authorizations or state or federal permits) as may be 

necessary for proper characterization of the discharge.

1306.3 DISCHARGE DATA AVAILABLE TO THE PUBLIC

A. Public Access to Data

All discharge data obtained by the Board, including data reported pursuant 

to Rule 1306.2 and Article 17(B) of the Environmental Public Policy Act, 

12 LPRA § 8002 k (b), shall be made available for public inspection and 

shall also be made available to the public in any additional way that the 

Board may deem appropriate.

B. Presentation of Data

All discharge data shall be presented in such a manner as to show the 

relationship between measured or estimated discharge and the discharge 

allowed under the Applicable Rules and Regulations.

1306.4 MALFUNCTION OF EQUIPMENT REPORT

In the event that any water pollution control equipment or related facility 

breaks down in such manner as to cause the discharge of pollutant in 

violation of the Applicable Rules and Regulations, the person responsible for 

the equipment shall provide a statement giving all pertinent facts, including 

the estimated duration of the breakdown. The Board shall be notified when 

the condition causing the failure or breakdown has been corrected and the 

equipment is again in operation. When required by the Board, this notification 

shall be followed by a written report of the incident. This report shall include 

specific data concerning the affected equipment, date and hour of the 

occurrence, causes of the malfunction, and corrective measures taken. 

1306.5 EMERGENCY PLAN

The Board may require the owner of any source to provide or contract the 

services for equipment and materials necessary for controlling spills of oil 

and/or hazardous substances. This Board may also require the owner of any 

source to take all necessary measures to control nontoxic spills that may 

cause a disagreeable taste or odor to the waters. The source must have an 
59

emergency plan for prompt action in case of spills. Said plan must be 

prepared according to the Emergency Plan of the Commonwealth of Puerto 

Rico. The Emergency Plan requirements will be included in the guides 

developed or adopted by the Board concerning this matter.

1306.6 PERSONNEL AND WATER POLLUTION CONTROL EQUIPMENT

A. General

1. All water pollution control equipment shall be installed, maintained and 

operated in such manner as to allow compliance with Applicable Rules 

and Regulations.

2. All pollutants removed from the wastewater shall be disposed at the 

intervals required for maintaining optimum operational efficiency. The 

disposal of removed pollutants shall be in accordance with Applicable 

Rules and Regulations and in such a manner as to prevent 

environmental degradation.

3. Where required by this Board, and particularly for those sources where 

pollution would result in an imminent danger to human health or life, 

stand-by equipment shall be provided to insure continuous operation.

B. Operation

Following the issuance of licenses by the Potable Water and Wastewater 

Treatment Plant Operators Examining Board of the Commonwealth of 

Puerto Rico, all wastewater facilities, whether publicly or privately owned, 

must be operated by an operator licensed by such Examining Board.

1306.7 MINIMUM TREATMENT REQUIRED

The minimum treatment required for any wastewater must be at such level 

that discharges shall meet effluent limits as established under Section 301 of 

the Clean Water Act, as amended, 33 U.S.C. § 1311, and shall not cause the 

water quality standards, as set forth in Rules 1302 and 1303 of this 

Regulation, to be contravened, except as provided under Rule 1304.

1306.8 STANDARDS FOR SUBSTANCES AT CONCENTRATIONS BELOW THE 

DETECTION LEVEL

In those cases where a standard for a particular substance is below the 

detection level of the approved analytical methods, in accordance with Rule 

1306.2 (C), this Board may require, in any permit, order, authorization or 

certificate issued by the Board, that such substance be analyzed by the 

approved analytic method with the lowest detection level, in accordance with 
60

Rule 1306.2 (C). The applicable limit in these cases shall be that the 

substance is not detectable by such method.

1306.9 TOXICITY TESTS

This Board may request to any point source to conduct acute toxicity tests of 

its wastewater discharges. Based upon an evaluation of the test results, this 

Board may require additional toxicity tests, including chronic tests and 

toxicity/treatability studies, and may impose toxicity limitations.

1306.10 SITE-SPECIFIC WATER QUALITY STANDARDS

The Board or any interested person may develop, in accordance with the 

requirements of 40 CFR Part 131 and guidelines developed pursuant to such 

federal regulation, site-specific water quality criteria where such criteria are 

considered necessary. When the criterion is to be developed by an interested 

person, that person must submit, for the Board's approval, a protocol of all the 

procedures, conditions, organisms and sites that will be considered by such 

person to develop the criterion. The Board may adopt a criterion developed 

in accordance with this Rule as a water quality standard pursuant to the 

procedures established under 40 CFR Part 131.20.

1306.11 WATER QUALITY CERTIFICATE

A. The water quality standards promulgated by this Regulation are not 

concentration limits applicable to the effluent. These standards are 

applicable to the receiving water body. When requesting a Water Quality 

Certificate, the petitioner must submit, as part of the application, a 

characterization of the effluent, the receiving water body and the limits 

which the petitioner requests be applicable to the effluent, together with a 

detailed analysis of the method(s) used to translate the water quality 

standards into effluent limitations and the justification for their use. The 

petitioner must demonstrate to the satisfaction and requirement of the 

Board that the limits requested shall not cause a violation of the water 

quality standards at the receiving water body, taking into account the 

procedures of waste load allocation (Rule 1310), compliance plans (Rule 

1306.12), determination of mixing zones (Rule 1305), and the provisions 

for intermittent water bodies (Rule 1304) or any other defensible method 

that is also acceptable by the Board. In no case shall it be allowed that 

any discharge will cause a violation of the water quality standard in the 

receiving water body (coastal, surface, estuarine and ground waters), if 

the average calculated from the flow proportional composite samples 

taken in a 24 hour period exceed the maximum limit allowed for that 

specific parameter as established in Rule 1303. For those substances for 

which it is not possible to take composite samples, the determination of 

non compliance with the standards will be done using grab samples. The 
61

Board reserves the right to intervene with any discharge of pollutants that 

affects the quality of a receiving water body in a given moment. This 

includes setting limits on any substances not specifically listed in this 

Regulation and also regulate the manner in which a discharge take place, 

when the Board finds that such intervention is necessary to protect the 

quality and the designated uses of the receiving water body.

B. The Board will publish a public notice in a newspaper of wide circulation in 

Puerto Rico informing the Board's intention to grant or deny any Water 

Quality Certificate requested pursuant to the Clean Water Act. The cost of 

the publication of such notice will be paid by the petitioner of the 

corresponding permit object of the referred Water Quality Certificate. The 

Board will notify the petitioner of the permit, fifteen (15) days prior to the 

publishing date of the public notice, of the payment requirement for the 

publication of such notice in order to allow the petitioner to proceed with 

the corresponding payment.

1306.12 COMPLIANCE PLAN

A. The Board may consider and approve a Compliance Plan for any existing 

facility that is not in compliance with the provisions of this Regulation. 

Such Compliance Plan may be requested by a petitioner of any water 

quality certificate, approval, permit or authorization under consideration of 

the Board. Such petition must be submitted to the Board with the 

following information:

1. Evidence which demonstrates, to the satisfaction of the Board, the 

need of a Compliance Plan. 

2. The proposed Compliance Plan which indicates the manner in which 

such facility will meet full compliance with all the applicable provisions 

of this Regulation, using the best engineering practices and as soon as 

possible.

B. The effective period of the Compliance Plan shall not exceed a maximum 

period of three (3) years, except upon request of the interested person 

and when it is demonstrated that conditions, which make necessary an 

extension of such period still exist. In this case the Board may grant an 

extension of the effective period of the Compliance Plan that will not 

exceed two (2) years.

C. The Board may impose any condition considered necessary to assure full 

compliance with the provisions of this Regulation as soon as possible.

D. The Board may revoke the approval of a Compliance Plan for any of the 

following reasons:
62

1. The petitioner has not revealed all the relevant facts in the request or 

has provided false representation of any of the relevant facts during 

the evaluation of such request.

2. Non-compliance with any provision of the Compliance Plan.

3. Changes in the conditions under which the Compliance Plan was 

approved, without due authorization from the Board.

4. There exists an imminent hazard to public health or the environment.

E. The Board reserves the right to supervise and oversee the actions of the 

petitioner concerning the performance of the Compliance Plan.
63

RULE 1307 PENALTIES

Any violation of this Regulation will constitute a felony and will be subject to the 

penalties established by the Public Policy Environmental Act, Law No. 416 of 

September 22, 2004, as amended. Moreover, the Board may, in case of infraction of 

any of the Applicable Rules and Regulations, suspend, amend, or revoke any 

certification, approval, or other authorization issued under this Regulation.
64

RULE 1308 ADDITIONAL PROVISIONS

1308.1 PUBLIC NUISANCE

A. Nothing in this Regulation shall be construed to authorize or legalize the 

creation or maintenance of a public nuisance, as defined in Rule 1301 of 

this Regulation.

B. This Rule shall not be understood as a limit or restriction of the other 

prohibitions established in other parts of this Regulation.

1308.2 CONFLICTIVE OR CONTRADICTORY PROVISIONS

If a requirement established by any provision of this Regulation is either more 

restrictive or less restrictive than a requirement established by any other 

provision of this Regulation, or by any other law, regulation, standard, or limit 

established by any duly constituted governmental authority having jurisdiction, 

the requirement which is more restrictive shall apply.

1308.3 DEROGATION

This Regulation nullifies any previous provision, resolution, agreement, or 

regulation of the same subject, which may contradict this Regulation.

1308.4 SEPARABILITY CLAUSE

If any provision of this Regulation is declared illegal or unconstitutional by 

decision of a court, such declaration or decision will not affect the other 

provisions of this Regulation, each one being considered as separate.

1308.5 EFFECTIVENESS

This Regulation shall go into effect thirty (30) days after the date of its filing at 

the Department of State, in conformity with Law 170 of August 12, 1988, as 

amended, Ley de Procedimiento Administrativo Uniforme.

1308.6 REVIEW AND AMENDMENTS TO THIS REGULATION

A. Review, Amendments and Effective Date of Amendments

The Board shall review this Regulation, not later than three (3) years after 

the last adopted amendments, to consider possible amendments. If as a 

result of the review, it is necessary to make amendments to this 

Regulation, they will be adopted in conformity with the procedures 

established in the applicable Commonwealth of Puerto Rico and federal 

rules and regulations. Such amendments shall be in effect thirty (30) days 
65

after the date of its filing at the Department of State, or immediately 

through the issuance of an Executive Order in conformity with the 

provisions of Law 170 of August 12, 1988, as amended, Ley de 

Procedimiento Administrativo Uniforme.

B. Mandatory Public Hearing to adopt Amendments

The Board shall not adopt any amendment without holding a public 

hearing and complying with the public notice requirements, established in 

Rule 1308.6 (C).

C. Notice of Mandatory Public Hearings

1. The Board will provide notice of the date, time, place, and subject of 

each mandatory public hearing to amend this Regulation. Such 

notification shall be made at least forty-five (45) days prior to the 

hearing, by publishing a public notice in two (2) newspapers of wide 

circulation on the Island. The Board may make additional notification 

in any manner it deems appropriate.

2. Such notification of hearings shall indicate at least one location where 

the full text of the proposed amendment will be available for public 

inspection.

D. Effect of Pending Amendment

1. For purposes of this Rule, an amendment is "pending" from the date of 

first publication of the notification of public hearing on the amendment.

2. Notwithstanding any other provision of this Regulation, while any 

amendment to this Regulation is pending, any water quality certificate, 

approval, permit, or authorization under consideration by the Board, 

shall be based on the current Regulation at the moment of the request, 

and shall be conditioned to the immediate applicability of the 

amendment upon the date of effectiveness of such amendment, unless 

the petitioner of the water quality certificate, approval, permit or 

authorization requests and obtains the approval of a Compliance Plan 

in accordance with Rule 1306.10 of this Regulation. 

3. Water quality certificates, approvals, permits or authorizations issued 

under the current Regulation prior to the pending amendment, shall 

remain unaltered until the date of renewal, extension or expiration.

If a person considers that a benefit may be obtained from an 

amendment made to this Regulation, that person may request from the 

Board the modification of the issued water quality certificate, approval, 
66

permit or authorization. The Board will determine after receiving a 

supported request, whether or not to grant such modification, based on 

the circumstances of each case. If the Board determines to grant the 

requested modification, the water quality certificate, approval, permit or 

authorization will be totally reviewed in accordance with the Applicable 

Rules and Regulations.
67

RULE 1309 RESERVED
68

RULE 1310 WASTE LOAD ALLOCATION

1310.1 GENERAL

The waste load allocation (WLA) analysis will be used as a mechanism to 

develop water quality-based effluent limits for a discharge to high quality 

surface or estuarine waters, in order to have a reasonable assurance that the 

allowed discharge will not cause violations to the applicable water quality 

standards of the receiving water body at the immediate vicinity of the 

discharge.

1310.2 WLA APPLICATIONS

Whenever a waste load allocation analysis is requested or the Board 

determines that it is necessary to allocate the assimilative capacity of 

contaminants in a segment of a water body, the Board shall request from 

each point source to complete and submit, within sixty (60) days after 

receiving the Board's notification, an Application for a Waste Load Allocation 

(AWLA). If any point source needs more than sixty (60) days to complete and 

submit the AWLA, the point source shall submit a written request for a time 

extension to submit the AWLA at least ten (10) days before the due date of 

submission of the AWLA. Such request shall include the reasons for which 

the point source is unable to submit the AWLA within the period of time 

specified in this Rule. If the point source fails to submit the AWLA in 

accordance with the requirements specified in this Rule, that point source 

shall comply with all applicable water quality standards at the point of 

discharge.

Each application shall be submitted using the Form WLA-01.

Each point source shall include together with the AWLA the following:

A. Evidence that the project has complied with the provisions of Article 4 (B) 

(3) of the Law No. 416 of September 22, 2004, Environmental Public 

Policy Act, as amended (previously Article 4-C, of the derogated Law No. 

9 of June 18, 1970, Environmental Public Policy Act, as amended), if the 

application is related to a new or modified discharge.

B. Diagram showing the existing and future discharges.

1310.3 CONDITIONS FOR WASTE LOAD ALLOCATIONS

A. Minimum Treatment Required

No allocation shall be performed to any point source that does not meet 

the requirements of Section 301(b) of the Clean Water Act.
69

B. Property Right

Allocations will not be transferable and do not convey any property rights 

of any sort or any exclusive privileges, nor do they authorize any injury to 

persons or property or invasion of other private rights, or any infringement 

of Federal or State laws or regulations.

C. pH

No allocation shall be performed to any point source that does not meet 

the applicable pH water quality standard at the point of discharge.

D. Design Flows

1. Receiving Water Bodies Design Flow

For the purpose of determining the assimilative capacity of a water 

body the following design minimum flows will be used:

a. 7Q10 for Aquatic Life criteria except for Cyanide (Free CN), Silver, 

and Ammonia

b. 7Q2 for Biochemical Oxygen Demand (BOD5), Dissolved Oxygen, 

Ammonia and those substances included in Rule 1303.2

c. 1Q10 for Cyanide (Free CN), Silver and Lindane

d. 30Q5 for Human Health criteria for non-carcinogen substances

e. HMF for Human Health criteria for carcinogen substances

f. Where the quantity of flow is altered by human-induced activities or 

work, and such alteration results in flow variations significantly 

different from natural patterns of variations, the Board may 

establish a design flow in a case by case basis, to reflect the effects 

of such flow variations.

g. In the cases of lakes, reservoirs and estuarine waters, the Board 

will determine the characteristics upon which to establish waste 

load requirements with respect to the particular characteristics of 

the receiving water body.
70

2. Discharge Design Flow

The discharge design flow shall be the wastewater treatment plant 

design flow or the twenty-four (24) hours maximum discharge flow 

whichever is greater. In those cases where the treatment plant 

capacity is significantly larger than the maximum flow of the discharge 

in twenty-four (24) hours, the Board, upon request of the interested 

party, may perform the WLA using the maximum flow of the discharge 

in twenty-four (24) hours, when demonstrated to the satisfaction of the 

Board that the use of such flow is adequate. In those cases, the 

interested party should submit a petition to the Board requesting that 

the WLA be performed with the maximum flow of the discharge in 

twenty-four (24) hours. If the petition is approved by the Board, the 

WLA will be performed in accordance with said petition and taking into 

consideration the increase in flow during the effective period of the 

WLA.

E. Total Allowable Pollutant Load

The total allowable pollutant load (TAPL) is the maximum amount of a 

pollutant (i.e. the sum of the individual point sources, the individual 

existing or future non-point sources, the natural background sources and 

the reserve) that a water body can receive and still meet the water quality 

standards.

F. Sum of the Non-point Source Load

The sum of the non-point source loads (NPSL) is equal to the natural 

background sources of pollution plus the sum of the individual non-point 

sources.

G. Maximum Daily Load Allowable

The maximum daily load allowable (MDLA) is the maximum load that can 

be allocated among the point sources without causing a violation to the 

water quality standard.

The MDLA of a substance x is equal to the TAPL of the substance x 

minus the sum of the load allocation of the substance x.

H. Reserves

In each segment, as part of the initial allocation, a reserve (R) of 25% of 

the MDLA of each pollutant shall be set by the Board, except when it is 

demonstrated to the satisfaction of the Board that existing conditions merit 

a reserve of less than 25%. In such cases, a written request shall be 
71

submitted to the Board by the interested party, indicating the reasons for 

which a reserve less than 25% is necessary. If the request is approved by 

the Board, the WLA shall be performed in accordance with such request.

1. The reserve in each segment shall be utilized to allow for economic 

development and population growth, which may occur subsequent to 

the initial allocation, or any reallocation, when approved by the Board. 

The priority to utilize the reserve shall be directed towards the 

governmental infrastructure necessary to allow for said economic 

development and population growth.

2. Particular allocations or portions of allocations, which are no longer 

needed or used by the source or facility to which they were assigned 

shall be revert to the reserve.

1310.4 DISSOLVED OXYGEN WLA

The dissolved oxygen in water bodies is affected by the biochemical oxygen 

demand and the ammonia. Therefore the Board will perform a WLA analysis 

in accordance with Chapter 6, Section II of the Waste Load Allocation 

Guidelines.

1310.5 ALLOCATIONS

The Board shall allocate the allowable loads among the different point 

sources in such a manner that compliance with all applicable water quality 

standards is maintained. The allowable loads shall be allocated among the 

different point sources as follows:

A. The Board shall identify all the point sources for which the WLA shall be 

performed.

B. The Board shall request from each point source for which a WLA shall be 

assigned to complete an AWLA within sixty (60) days after receiving the 

Board notification.

C. If any point source fails to submit the AWLA in the specified time period 

and fails to submit a request of time extension to submit the AWLA, such 

point source shall comply with all applicable water quality standards at the 

point of discharge.

D. The Board, using the information provided in the AWLA and any other 

data obtained from the Environmental Protection Agency and the 

Environmental Quality Board database or other sources and assuming 

that all the substances are conservative, except the ones that may deplete 

the dissolved oxygen, shall determine:
72

1. The substances for which the WLA shall be performed.

2. The TAPL, NPSL, MDLA, R, WLA and equitable allowable 

concentration (EAC) for each substance for which the waste load 

allocation shall be performed.

E. If for any substance the background concentration is greater than the 

applicable water quality standard, then the maximum allowable effluent 

concentration (MAEC) shall be equal to the water quality standard for all 

discharges.

F. If for any substances the EAC is less than the applicable water quality 

standard, then the MAEC shall be equal to the water quality standard for 

each discharge, except for dissolved oxygen for which the Board shall 

perform the WLA as specified on Rule 1310.4 of this Regulation.

G. If for a given discharge the EAC is greater than the maximum requested 

effluent concentration (MREC), the MAEC for that given discharge shall be 

equal to MREC.

H. If for all discharges the EAC of a given substance is less than the MREC, 

then the MAEC of that given substance shall be equal to the EAC.

I. If for one or more discharges the MREC of a given substance is less than 

the EAC of that substance, and one or more discharges have the MREC 

of such substance greater than the EAC, the EAC may be recalculated as 

follows:

Uaps

x T BGx LTEx LTE

rx Q

WQS Q C C Q

EAC =

0.75 q

where: 

EACrx = the recalculated equitable allowable concentration of a 

substance x for the discharges with MREC greater than 

the EAC of the substance x

WQSx = quality standard of substance x

QT = total flow of all discharges

CBGx = background concentration of substance x

q = design flow of the receiving water body according to Rule 

1310.3 (D)

CLTEx = concentration of a substance x less than the EAC
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QLTEx = flow of discharges with concentration of the substance x

less than EAC

QUaps = sum of the flows of unallocated point sources discharges

J. If after the Board performed the WLA, one or more existing point sources 

are not meeting the WLA-based effluent limitations, a compliance plan 

shall be submitted, for the Board approval, by such point sources 

indicating the way in which those point sources will attain compliance with 

the applicable water quality standards.

1310.6 REALLOCATIONS

All allocations are subject to review by the Board and, after such review, the 

Board may perform reallocations as it deems necessary

The Board will review the WLA:

A. If any factor or condition upon which a particular allocation is based 

changes significantly;

B. When a segment of a water body is not meeting the water quality 

standards after the Board performed a WLA;

C. When, in the judgment of the Board, the existing allocations are no longer 

equitable. 

In making a reallocation, the Board shall utilize the same procedure for 

allocations in accordance with Waste Load Allocation Guidelines and Rule 

1310.5 of this Regulation. 

1310.7. EFFECTIVENESS OF THE WLA

The WLA shall go into effect after being incorporated into the NPDES permit, 

and it will be valid until the NPDES permit expired; except when the WLA is 

revoked by the Board.

1310.8 REVOCATION

The Board may revoke a WLA for the following reasons:

A. The petitioner's failure to fully disclose all relevant facts in the application 

or renewal, or the petitioner's misrepresentation of any relevant fact during 

the WLA evaluation or validation process;

B. Non-compliance with any applicable provision of this Regulation;
74

C. Changes in the conditions under which the WLA was performed, including, 

but not limited to, background concentration, discharge flow, receiving 

water body flow and effluent characteristics, as originally approved by the 

Board;

D. There is an imminent threat to human health or the environment.

1310.9 PROCEDURE FOR REVOKING A WLA 

If there are reasons to revoke a WLA, the Board shall notify the person to 

whom the waste load allocation was granted indicating the intention of 

revoking the WLA by means of a Show Cause Order. The procedures to 

follow are those specified in the Board's Internal Regulations for 

Administrative Hearings. Notwithstanding the foregoing, the Board may 

immediately revoke a WLA without previous notice, or the opportunity of 

hearings if there is an imminent threat to human health or the environment.

1310.10 COST INCURRED BY THE BOARD PERFORMING A WLA

The point sources shall pay to the Board any cost incurred by the Board in the 

performance of any WLA.

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ATTACHMENT

ENVIRONMENTAL QUALITY BOARD

ANTI-DEGRADATION POLICY IMPLEMENTATION PROCEDURE
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ENVIRONMENTAL QUALITY BOARD

ANTI-DEGRADATION POLICY IMPLEMENTATION PROCEDURE

Puerto Rico’s Anti-degradation Policy is set forth in the Puerto Rico Water Quality 

Standards Regulation (PRWQSR). The goal of this Policy is to conserve, maintain and 

protect the designated and existing uses of the waters of Puerto Rico and the water 

quality necessary to protect these uses.

It is the desire of the Commonwealth of Puerto Rico to incorporate all of the existing 

elements of Puerto Rico’s Anti-degradation Implementation Procedure, either explicitly 

or by reference, into one document so that it is readily accessible to the public and 

regulated community. Therefore, in order to promote the aforementioned policy the 

Environmental Quality Board (EQB) has developed the following implementation 

procedure as part of the PRWQSR.

I. General Policy Statement

A All point sources of pollution are subject to an anti-degradation review.

B An anti-degradation review shall be initiated as part of the certification 

process required by Section 401-“Certification” of the Clean Water Act 

(CWA).

C The 401 Certification Process shall follow the procedure established by the 

Resolution R-89-2-2 of the Governing Board of EQB.

D The following are not subject to the anti-degradation review due to the fact 

that they are non discharge systems and are managed by specific 

regulations:

1. All Non-Point Sources of Pollution

2. Underground Storage Tanks

3. Underground Injection Facilities

E The protection of water quality shall include the maintenance, migration, 

protection, and propagation of desirable species, including, threatened or 

endangered species identified in the local or federal regulations.
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II. Definitions

A All the definitions included in Rule 1301 of the PRWQSR, as amended, are 

applicable to this procedure.

B High Quality Waters

1. Are waters whose quality is better than the mandatory minimum level 

to support the CWA’s goals of propagation of fish, shellfish, wildlife 

and recreation in and on the waters. High Quality Waters are 

identified by EQB on a parameter-by-parameter basis.

C Outstanding National Resources Waters (ONRWs)

1. Are waters classified as SA or SE in the PRWQSR, as amended, or 

any other water designated by Resolution of the Governing Board of 

EQB. ONRWs are waters that are recreationally or ecologically 

important, unique or sensitive.

III. Anti-degradation Review Procedure

The anti-degradation review will commence with the submission of the water 

quality certificate request in accordance with Section 401 of the CWA. The EQB 

uses a parameter-by-parameter approach for the implementation of the antidegradation policy and will review each parameter separately as it evaluates the 

water quality certificate request. Any point source of pollution subject to the 401 

certification/antidegradation review process shall comply with Article 4 (B) (3) of 

the Law No. 416 of September 22, 2004, Environmental Public Policy Act, as 

amended [12 LPRA § 8001] (previously Article 4-C of the derogated Law No. 9

of June 18, 1970, Environmental Public Policy Act, as amended [12 LPRA § 

1124(c)]. Compliance with Article 4 (B) (3) shall be conducted in accordance 

with the Reglamento de la Junta de Calidad Ambiental para el Proceso de 

Presentación, Evaluación y Trámite de Documentos Ambientales (EQB’s 

Environmental Documents Regulation). During the evaluation process of the 

environmental document an alternatives analysis shall be conducted (12 LPRA § 

8001(a)(5), EQB’s Environmental Documents Regulation, e.g., Rules 211E and 

253C), and a public participation period and a public hearing shall be provided 

(12 LPRA § 8001(a), EQB’s Environmental Documents Regulation, Rule 254).

In conducting an anti-degradation review, the Water Quality Area (WQA) of EQB 

will sequentially apply the following steps:

A Determine which level of anti-degradation applies

1. Tier 1 – Protection of Existing and Designated Uses
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2. Tier 2 – Protection of High Quality Waters

3. Tier 3 – Protection of ONRWs

B Review existing water quality data and other information submitted by the 

petitioner. The applicant shall provide to the WQA the information 

regarding the discharge required by the PRWQSR including, but not limited 

to the following:

1. A description of the nature of the pollutants to be discharged

2. Treatment technologies applied to the pollutants to be discharged

3. Nature of the petitioner’s business

4. Daily maximum and average flow to be discharged

5. Effluent characterization

6. Effluent limitations requested to be applied to the discharge according 

to Rule 1306.11 of the PRWQSR

7. Location of the point of discharge

8. Receiving water body name

9. Water quality data of the receiving water body

10. Receiving water body minimum flow (7Q2 and 7Q10) for stream 

waters

11. Location of water intakes within the water body

12. In the event that the proposed discharge will result in the lowering of 

water quality, data and information demonstrating that the discharge 

is necessary to accommodate important economic or social 

development in the area where the receiving waters are located

C Determine if additional information or assessment is necessary to make the 

decision.

D The WQA prepares an intent to issue or deny the water quality certificate 

and publishes a notice in a newspaper of wide circulation in Puerto Rico 

informing the public of WQA’s preliminary decision and granting a public 

participation period of at least thirty (30) days.
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E Address the comments received from the interested parties and consider 

such comments as part of the decision making process.

F The EQB makes the final determination to issue or deny the requested the 

water quality certificate. Such decision is subject to the reconsideration 

procedure established in Law Number 170 of August 12, 1988, as 

amended, Ley de Procedimiento Administrativo (3 LPRA § 2165).

IV. Implementation Procedures

A Activities Regulated by NPDES Permits

1. Tier 1 – Protection of Existing and Designated Uses (Figure 1):

a. Tier 1 waters are:

i. Those waters of Puerto Rico (except Tier 2 or Tier 3 

waters) identified as impaired and that have been 

included in the list required by Section 303(d) of the 

CWA; and

ii. Those waters of Puerto Rico (except Tier 2 and Tier 3 

waters) for which attainment of applicable water quality 

standards has been or is expected to be, achieved 

through implementation of effluent limitations more 

stringent than technology-based controls (Best 

Practicable Technology, Best Available Technology and 

Secondary Treatment).

b. To implement Tier 1 anti-degradation, EQB must determine if a 

discharge would lower the water quality to the extent that it 

would no longer be sufficient to protect and maintain the 

existing and designated uses of that water body.

c. When a water body has been affected by a parameter of 

concern causing it to be included on the 303(d) List, then the 

WQA will not allow an increase of the concentration of the 

parameter of concern or pollutants affecting the parameter of 

concern in the water body. This “no increase” will be achieved 

by meeting the applicable water quality standards at the end of 

the pipe. Until such time that a Total Maximum Daily Load 

(TMDL) is developed for the parameter of concern for the 

water body, no discharge will be allowed to cause or contribute 

to further degradation of the water body.
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d. When the assimilative capacity of a water body is not sufficient 

to ensure maintenance of the water quality standard for a 

parameter of concern with an additional load to the water 

body, then the WQA will not allow an increase of the 

concentration of the parameter of concern or pollutants 

affecting the parameter of concern in the water body. This “no 

increase” will be achieved by meeting the applicable water 

quality standards at the end of the pipe. Until such time that a 

TMDL is developed for the parameter of concern for the water 

body, no discharge will be allowed to cause or contribute to 

further degradation of the water body.

2. Tier 2 – Protection of High Quality Waters (Figure 2):

a. To verify that a water body is a high quality water for a 

parameter of concern which initiates a Tier 2 anti-degradation 

review, the WQA must evaluate and determine:

i. The existing water quality of the water body;

ii. The projected water quality of the water body pursuant to 

the procedures established in the applicable provisions of 

Rules 1305 and 1310 of the PRWQSR, including but not 

limited to, Rules 1305.2, 1305.3, 1305.4, 1310.2, 1310.3, 

1310.4, 1310.5, and 1310.6; 

iii. If the existing and designated uses of the water body will 

be fully maintained and protected in the event of a 

lowering of water quality.

In multiple discharge situations, the effects of all discharges 

shall be evaluated thru a waste load allocation analysis in 

accordance with the applicable provisions of Rule 1310 of the 

PRWQSR or the applicable provisions of Rule 1305 regarding 

mixing zones.

b. In order to allow the lowering of water quality in high quality 

waters, the applicant must show and justify the necessity for 

such lowering of water quality through compliance with the 

requirements of Rule 1306.11 of the PRWQSR. EQB will not 

allow the entire assimilative capacity of a water body for a 

parameter of concern to be allocated to a discharger, if the 

necessity of the requested effluent limitation for the parameter 

of concern is not demonstrated to the full satisfaction of EQB.
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3. Tier 3 – Protection of ONRWs (Figure 3):

The EQB may designate a water as Class SA or SE (ONRWs) thru a 

Resolution (PRWQSR Rules 1302.1 (A) and 1302.2 (B)). 

Additionally, any interested party may nominate a specific water to be 

classified as an ONRW and the Governing Board of EQB will make 

the final determination. Classifying a water as an ONRW may result 

in the water being included in either Rule 1302.1 (A) or 1302.2 (B) of 

the PRWQSR, which would require an amendment of the PRWQSR. 

The process for amending the PRWQSR, including public 

participation, is set forth in Rule 1308.6 of said regulation.

a. The existing characteristics of Class SA and SE waters shall 

not be altered, except by natural causes, in order to preserve 

the existing natural phenomena.

i. No point source discharge will be allowed in ONRWs.

B Activities Regulated by CWA Section 404 or Rivers and Harbors Act 

Section 10 Permits (Discharge of Dredged or Fill Material)

The EQB will allow the discharge of dredged or fill material into a wetland if 

it can be demonstrated that such discharge will not have an unacceptable 

adverse impact either individually or in combination with other activities 

affecting the wetland of concern. The impacts to the water quality or the 

aquatic or other life in the wetland due to the discharge of dredged or fill 

material should be avoided, minimized and mitigated.

The discharge of dredged or fill material shall not be certified if there is a 

practicable alternative to the proposed discharge which would have less 

adverse impact on the recipient ecosystem, so long as the alternative does 

not have other more significant adverse environmental consequences. 

Activities which are not water dependent are presumed to have practicable 

alternatives, unless the applicant clearly demonstrates otherwise. No 

discharge of dredged and fill material shall be certified unless appropriated 

and practicable steps have been taken which minimize potential adverse 

impacts of the discharge on the recipient ecosystem. The discharge of 

dredged or fill material to ONRWs, however, shall be governed by 

paragraph IV.(A) (3).
FIGURE 1

Tier 1: Protecting of Existing

and Designated Uses

Determine which level of 

anti-degradation applied

Prepare an Intent to Issue a Water 

Quality Certificate (WQC) with 

Water Quality Standards as 

effluent limitations or an Intent to 

Deny the WQC

Public Participation 

Period of 30 days is 

provided 

Comments are considered

EQB makes a final decision
FIGURE 2

Determine which level of antidegradation applied

Tier 2: Protection of High Quality Waters

Prepare an intent to issue or deny a 

Water Quality Certificate

Public Participation Period of 30 days 

is provided 

Comments are considered

EQB makes a final decision

Review all the relievable existing data, 

assimilative capacity of the receiving

waterbody and determine if the 

discharge would lower the water 

quality of the receiving waterbody
FIGURE 3

Tier 3: Protection of Outstanding 

National Resources Waters

Determine which level of

antidegradation applied

Prepare and issue an 

Intent to Deny a Water 

Quality Certificate

Public Participation 

Period of 30 days is 

provided 

Comments are considered

EQB makes a final decision