1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program...

44
1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard Proposed Water Quality Standard for for Natural Conditions Natural Conditions Public Work Shops Public Work Shops Fairbanks – August 29, 2006 Fairbanks – August 29, 2006 Anchorage – August 30, 2006 Anchorage – August 30, 2006 Juneau – August 31, 2006 Juneau – August 31, 2006

Transcript of 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program...

Page 1: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

1

Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program

Proposed Water Quality Proposed Water Quality Standard for Standard for

Natural ConditionsNatural Conditions

Public Work Shops Public Work Shops Fairbanks – August 29, 2006Fairbanks – August 29, 2006Anchorage – August 30, 2006Anchorage – August 30, 2006

Juneau – August 31, 2006Juneau – August 31, 2006

Page 2: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

2

Public Hearing Public Hearing

Anchorage – September 18Anchorage – September 18thth

4:00 – 6:00 PM4:00 – 6:00 PMLegislative Information OfficeLegislative Information Office

1-888-295-45461-888-295-4546

Proposed Water Quality Proposed Water Quality StandardStandard

for Natural Conditionsfor Natural Conditions

Page 3: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

3

Work Shop PresentersWork Shop Presenters

Jim PowellJim PowellSection Manager, Water Quality Standards Section Manager, Water Quality Standards

[email protected][email protected]

Nancy SonafrankNancy SonafrankProgram Manager, Program Manager,

Water Quality Assessment & Monitoring ProgramWater Quality Assessment & Monitoring Program

[email protected][email protected]

Jerry DiamondJerry DiamondTetra Tech, IncTetra Tech, Inc

Page 4: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

4

Work Shop AgendaWork Shop Agenda IntroductionIntroduction Problem and ProposalProblem and Proposal Public Review Process for Proposed Public Review Process for Proposed

RegulationRegulation Proposed RegulationProposed Regulation Review of Proposed Guidance Review of Proposed Guidance Questions and Answers Questions and Answers

Page 5: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

5

IntroductionIntroduction

Roles: DEC and Tetra Tech, Inc.Roles: DEC and Tetra Tech, Inc. Work Shop objectives:Work Shop objectives:

Describe what is being proposed and Describe what is being proposed and whywhy

Provide public review process for Provide public review process for revisionrevision

Provide a public forum for questions & Provide a public forum for questions & answersanswers

Ground rules and timeframeGround rules and timeframe

Page 6: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

6

What is the Problem?What is the Problem?

Challenges in permitting discharges Challenges in permitting discharges to waters with to waters with naturally low quality naturally low quality (Triennial Review priority)(Triennial Review priority)

Current regulations require site specific criteria Current regulations require site specific criteria that are “better” than the natural conditionthat are “better” than the natural condition

Not possible for actions where there is no Not possible for actions where there is no control over pollutant levels via treatmentcontrol over pollutant levels via treatment

No current procedures on how to No current procedures on how to determine natural determine natural levels of pollutantslevels of pollutants

Page 7: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

7

What is the Proposal?What is the Proposal?

Add a narrative (or descriptive) Add a narrative (or descriptive) standard for waters standard for waters where the natural condition where the natural condition is of lower quality than is of lower quality than

the statewide water quality criteria.the statewide water quality criteria.

Remove the site specific criteria Remove the site specific criteria provision for natural provision for natural conditions in: 18 AAC conditions in: 18 AAC 70.235(b).70.235(b).

Guidance adopted into regulationGuidance adopted into regulation

Guidance for the Implementation of Guidance for the Implementation of Natural Condition-Based Natural Condition-Based Water Quality StandardsWater Quality Standards

Page 8: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

8

What is the Proposal?What is the Proposal?

The guidance describesThe guidance describestwo methods for two methods for implementing a natural implementing a natural condition-based water condition-based water quality standard:quality standard:-Concurrent -Concurrent Measurement (preferred)Measurement (preferred)-Statistical -Statistical CharacterizationCharacterization

Page 9: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

9

Public Review Process for Public Review Process for Proposed RegulationProposed Regulation

Public notice – 45 day comment periodPublic notice – 45 day comment periodAugust 17 - Oct. 2, 2006August 17 - Oct. 2, 2006

Public workshops (3)Public workshops (3) Public hearing Public hearing

public testimony taken and entered in the public testimony taken and entered in the public recordpublic record

Consultation with other agenciesConsultation with other agencies DEC responds to commentsDEC responds to comments DEC drafts final revisions to the DEC drafts final revisions to the regulations and regulations and guidanceguidance

Page 10: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

10

Regulation Adoption ProcessRegulation Adoption Process

DEC Commissioner adopts DEC Commissioner adopts regulationsregulations

Department of Law ReviewDepartment of Law Review

Lt. Governor files regulationsLt. Governor files regulations

Regulations go into effect 30 days Regulations go into effect 30 days later for state later for state purposespurposes

EPA review and approval for CWA EPA review and approval for CWA purposespurposes

Page 11: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

11

Public Review ProcessPublic Review Process - Deadline for - Deadline for CommentsComments

WHEN:WHEN: 5 PM Alaska time, October 2, 20065 PM Alaska time, October 2, 2006

WHERE & WHO:WHERE & WHO: Send comments to:Send comments to:

Jim Powell, Section ManagerJim Powell, Section Manager

Water Quality Standards, Water Division Water Quality Standards, Water Division

Department of Environmental ConservationDepartment of Environmental Conservation

610 University Ave610 University Ave

Fairbanks, Alaska 99709Fairbanks, Alaska 99709

HOWHOW:: Fax to (907) 451-2187Fax to (907) 451-2187

E-MAIL: E-MAIL: Jim Jim [email protected]@dec.state.ak.us

Page 12: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

12

Natural Condition DefinitionNatural Condition Definition

Currently Defined in Currently Defined in

18 AAC 70.990(41):18 AAC 70.990(41): any physical, chemical, any physical, chemical,

biological, or biological, or radiological condition radiological condition existing in a waterbody existing in a waterbody before any human-before any human-caused influence on, caused influence on, discharge to, or discharge to, or addition of material to, addition of material to, the waterbodythe waterbody

Page 13: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

13

Proposed RegulationProposed Regulation

Proposed 18 AAC 70.010(c):Proposed 18 AAC 70.010(c): Where the Department determines that the natural Where the Department determines that the natural

condition of a water of the state is of lower quality than condition of a water of the state is of lower quality than the water quality criteria set out in 18 AAC 70.020(b), the the water quality criteria set out in 18 AAC 70.020(b), the natural condition supersedes the criteria and becomes the natural condition supersedes the criteria and becomes the standard for that water. In implementing water quality standard for that water. In implementing water quality standards based on the natural conditions in a permit, standards based on the natural conditions in a permit, certification or other written decision, the department will certification or other written decision, the department will follow the procedures set out in the follow the procedures set out in the Guidance for the Guidance for the Implementation of Natural Condition-Based Water Quality Implementation of Natural Condition-Based Water Quality Standards, Standards, dated August 16, 2006 adopted by reference. dated August 16, 2006 adopted by reference.

Page 14: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

14

Proposed Natural Condition Proposed Natural Condition GuidanceGuidance

The guidance is in the regulationThe guidance is in the regulation Natural Condition-Based Water Quality Natural Condition-Based Water Quality

Standards Standards (Natural Standard) (Natural Standard) Natural StandardNatural Standard

Types of parameters that apply Types of parameters that apply

Procedures for developing Procedures for developing

Methods for calculating standard Methods for calculating standard

Methods for calculating permit limitsMethods for calculating permit limits

Page 15: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

15

Applicable Water Quality Applicable Water Quality ParametersParameters

Potentially applicable to any parameter not Potentially applicable to any parameter not attributable to human activities:attributable to human activities: Bacteria due to wildlifeBacteria due to wildlife Metals from natural mineral depositsMetals from natural mineral deposits Nutrients from wildlife, vegetation, soilsNutrients from wildlife, vegetation, soils Sediments from natural runoff, geologySediments from natural runoff, geology Temperature, dissolved oxygen from seasonal Temperature, dissolved oxygen from seasonal

shiftsshifts Other parameters attributed to natural processes Other parameters attributed to natural processes

Page 16: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

16

Natural Standards Do NOT Natural Standards Do NOT Apply to:Apply to:

Human created substances:Human created substances: PCBsPCBs DioxinsDioxins Synthetic pesticidesSynthetic pesticides

Concentrations of any pollutant Concentrations of any pollutant attributable to human activitiesattributable to human activities

Page 17: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

17

Natural Conditions Process Natural Conditions Process OverviewOverview

Step 1. Exceedance Determination

Step 6. Recordkeeping

Step 5. Public Participation

Step 4. Express Natural Condition-Based Standards

Step 3. Areal Extent Determination

Step 2. Natural Condition Finding

Page 18: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

18

Step 1. Exceedance Step 1. Exceedance DeterminationDetermination

Statewide water quality criteria (Criteria) Statewide water quality criteria (Criteria) apply unless proven otherwiseapply unless proven otherwise

DEC must find that:DEC must find that:(1) the water quality is lower than the Criteria; (1) the water quality is lower than the Criteria;

andand

(2) the lower water quality is a result of natural (2) the lower water quality is a result of natural processesprocesses

Page 19: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

19

Exceedance Determination Exceedance Determination (cont.)(cont.)

Preferred ApproachPreferred Approach:: Record of natural Record of natural condition monitoring data from the waterbody of condition monitoring data from the waterbody of interestinterest

AlternateAlternate (if preferred approach is unavailable (if preferred approach is unavailable or unreasonable):or unreasonable): Records from nearby site Records from nearby site having similar characteristicshaving similar characteristics Data must be collected from the same watershed as Data must be collected from the same watershed as

the waterbody of interestthe waterbody of interest Applicable when no natural condition monitoring is Applicable when no natural condition monitoring is

possible in the waterbody of interest due to human possible in the waterbody of interest due to human activitiesactivities

Page 20: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

20

Step 2. Natural Condition Step 2. Natural Condition FindingFinding

DEC must find that Criteria exceedances are DEC must find that Criteria exceedances are the result of natural processes and not the result of natural processes and not human activityhuman activity The waterbody must be in a predominantly The waterbody must be in a predominantly

natural state: few roads, light recreational use, natural state: few roads, light recreational use, limited human activity, although not necessarily limited human activity, although not necessarily pristinepristine

Excludes watersheds with major hydrologic or Excludes watersheds with major hydrologic or riparian changesriparian changes

Page 21: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

21

Natural Condition Finding Natural Condition Finding (cont.)(cont.)

Must include:Must include: Why human activities are not directly or Why human activities are not directly or

indirectly the cause of the Criteria exceedance indirectly the cause of the Criteria exceedance for the pollutant of concernfor the pollutant of concern

Evidence that there has been minimal human Evidence that there has been minimal human activity in the watershed that would affect the activity in the watershed that would affect the water quality parameter in questionwater quality parameter in question

How natural processes are adequate to explain How natural processes are adequate to explain the observed exceedancesthe observed exceedances

Page 22: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

22

Step 3. Areal Extent Step 3. Areal Extent DeterminationDetermination

May include:May include: a single point in a a single point in a

waterbody waterbody a number of points a number of points

over an entire over an entire waterbodywaterbody

some portion of a some portion of a waterbodywaterbody

DEC will consider:DEC will consider: water quality water quality

informationinformation

groundwater and groundwater and surface water influences surface water influences

other natural processes other natural processes that affect water qualitythat affect water quality

To what “waterbody” does the Natural To what “waterbody” does the Natural Standard apply?Standard apply?

Page 23: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

23

Step 4. Expressing Natural Step 4. Expressing Natural Standards:Standards:

Two ApproachesTwo Approaches Concurrent Measurement ApproachConcurrent Measurement Approach

Compares natural reference site to the waterbody of Compares natural reference site to the waterbody of interestinterest

Preferred approachPreferred approach Statistical Characterization ApproachStatistical Characterization Approach

Used when concurrent approach is not practicable Used when concurrent approach is not practicable

( e.g., physical limitation) because there is no ( e.g., physical limitation) because there is no reference point that can be relied on to reflect reference point that can be relied on to reflect continuing natural conditionscontinuing natural conditions

Needs at least two years of data Needs at least two years of data Uses statistics to describe the natural conditionUses statistics to describe the natural condition

Page 24: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

24

Expressing Natural Standards Expressing Natural Standards (cont.)(cont.)

Two Approaches: Concurrent Two Approaches: Concurrent MeasurementMeasurementThe preferred The preferred

approach: approach:

Compares natural Compares natural reference site to reference site to the waterbody of the waterbody of interest.interest.

Up stream natural reference site

Down stream monitoring site

Borders of site

Discharge occur here

Page 25: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

25

Impact: Stream has been diverted

Alternate natural monitoring site

Discharge occurs here

Historic up stream natural reference site

Down stream monitoring site

Expressing Natural Standards Expressing Natural Standards (cont.)(cont.)

Two Approaches: Statistical AnalysisTwo Approaches: Statistical Analysis Historical Data Historical Data

CollectionCollection

Borders of site

0

1

2

3

4

5

6

0 10 20 30 40 50 60

Copper Concentration (µg/L)

Fre

qu

ency

Compare data with historical reference

Up stream natural reference site

Down stream monitoring site

Discharge Discharge MonitoringMonitoring

Page 26: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

26

Step 5. Public ParticipationStep 5. Public Participation

Any time DEC finds that the natural Any time DEC finds that the natural standard comprises the water quality standard comprises the water quality standard, the public will be notified and standard, the public will be notified and afforded an opportunity to commentafforded an opportunity to comment

Public notification, review, and opportunity Public notification, review, and opportunity for comment may be conducted for comment may be conducted independently or as part of an associated independently or as part of an associated action, such as a permitting decisionaction, such as a permitting decision

Page 27: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

27

Step 6. RecordkeepingStep 6. Recordkeeping

DEC will establish a record of every finding that DEC will establish a record of every finding that includes supporting documentation and technical includes supporting documentation and technical analysesanalyses

DEC will maintain an official list of the waterbodies DEC will maintain an official list of the waterbodies where Natural Standards have been found to applywhere Natural Standards have been found to apply

Page 28: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

28

Expressing Natural StandardsExpressing Natural Standards

Regardless of approach used, the applicant Regardless of approach used, the applicant must have:must have: Approved natural reference sites Approved natural reference sites Proper Quality Assurance and Quality Control Proper Quality Assurance and Quality Control

(QA/QC)(QA/QC) Appropriate statistics, data management and Appropriate statistics, data management and

metadata. metadata.

Page 29: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

29

Selection of Natural Reference Selection of Natural Reference SitesSites

A natural reference site must:A natural reference site must: Be free of significant upstream human disturbance; Be free of significant upstream human disturbance;

and and Have conditions comparable to the waterbody of Have conditions comparable to the waterbody of

interest.interest.

When using historic data, the applicant must When using historic data, the applicant must demonstrate that the site demonstrate that the site diddid meet natural meet natural reference site criteria during the time data reference site criteria during the time data collection took place.collection took place.

Page 30: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

30

Quality Assurance and Quality Quality Assurance and Quality ControlControl

QA/QC procedures must be identified and QA/QC procedures must be identified and used.used. Data collection in accordance with DEC generic Data collection in accordance with DEC generic

Quality Assurance Project Plan and Quality Quality Assurance Project Plan and Quality Management PlanManagement Plan

Analytical methods must be able to detect Analytical methods must be able to detect pollutant concentrations at the applicable DEC pollutant concentrations at the applicable DEC water quality standardwater quality standard

Page 31: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

31

Concurrent Measurement Concurrent Measurement ApproachApproach

Timing Timing Duplicate requiredDuplicate required Specified in permit monitoring requirementsSpecified in permit monitoring requirements If the effluent or downstream concentration If the effluent or downstream concentration

is less than or equal to the concurrent is less than or equal to the concurrent natural reference site measurement, then natural reference site measurement, then discharge is in compliance with the Natural discharge is in compliance with the Natural StandardStandard

Page 32: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

32

Concurrent Measurement Concurrent Measurement ApproachApproach

Objective: Ensure that water quality standards Objective: Ensure that water quality standards are met with a reasonable degree of assuranceare met with a reasonable degree of assurance

Noncompliance evaluated in two ways:Noncompliance evaluated in two ways: Any single measurement exceeds the concurrent Any single measurement exceeds the concurrent

reference condition by a statistically significant reference condition by a statistically significant marginmargin

Effluent concentrations Effluent concentrations persistentlypersistently exceed exceed reference conditions by any amountreference conditions by any amount

Permits must specify what is considered a Permits must specify what is considered a single or persistent exceedancesingle or persistent exceedance

Page 33: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

33

Statistical Characterization Statistical Characterization ApproachApproach

The statistical methodology similar to EPA’s Technical Support Document (TSD) approach for setting permit limits

Statistical characterization must(1) Meet minimum data requirements including any

necessary seasonal determination(2) Complete the required statistical analysis

Page 34: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

34

Statistical Characterization Statistical Characterization ApproachApproach

Minimum Data RequirementsMinimum Data Requirements

Must include at least 20 valid data pointsMust include at least 20 valid data points A minimum of two years of data must be A minimum of two years of data must be

collected, preferably three yearscollected, preferably three years Should have Should have << 20% frequency of non-detects 20% frequency of non-detects Must measure seasonal variabilityMust measure seasonal variability

Page 35: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

35

Statistical Characterization Statistical Characterization ApproachApproach

Seasonal DeterminationsSeasonal Determinations If seasonal water quality is significantly If seasonal water quality is significantly

different, then seasonal Natural Standards different, then seasonal Natural Standards will be necessary.will be necessary.

20 valid data points will be required for each 20 valid data points will be required for each season.season.

If data are insufficient for a season, If data are insufficient for a season, statewide Criteria apply.statewide Criteria apply.

Page 36: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

36

Statistical Characterization Statistical Characterization ApproachApproach

Seasonal DeterminationsSeasonal Determinations Conditions that may require seasonal Conditions that may require seasonal

Natural Standards include:Natural Standards include: High and low flowsHigh and low flows Seasonal variations in gaining or losing flowSeasonal variations in gaining or losing flow Seasonal variation in current patternsSeasonal variation in current patterns Seasonal thermal stratification in lakes and Seasonal thermal stratification in lakes and

estuariesestuaries Winter and summer conditionsWinter and summer conditions Ice coverageIce coverage Storm eventsStorm events

Page 37: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

37

Statistical Characterization Statistical Characterization ApproachApproach

Statistical Analysis Statistical Analysis Statistical terms used:Statistical terms used:

Mean – the average of all data pointsMean – the average of all data points 9090thth percentile – 90% of the natural conditions percentile – 90% of the natural conditions

data will be at or below this concentrationdata will be at or below this concentration

Page 38: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

38

Statistical Characterization Statistical Characterization ApproachApproach

Statistical AnalysisStatistical Analysis Natural conditions vary over time, so the Natural conditions vary over time, so the

Natural Standard must describe a distribution Natural Standard must describe a distribution of concentrations, not just one valueof concentrations, not just one value

The natural distribution is described by:The natural distribution is described by: the the meanmean of natural conditions data describes the of natural conditions data describes the

Natural Standard for long-term or chronic exposure. Natural Standard for long-term or chronic exposure. the the 9090thth percentile percentile of natural conditions data of natural conditions data

describes the Natural Standard for occasional or describes the Natural Standard for occasional or acute exposure.acute exposure.

Page 39: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

39

Example: Natural Condition Example: Natural Condition DataData

compared to chronic and acute Criteriacompared to chronic and acute Criteria

0

1

2

3

4

5

6

0 10 20 30 40 50 60

Copper Concentration (µg/L)

Fre

qu

en

cy

Ch

ron

icA

cute

Page 40: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

40

Natural Condition Example Natural Condition Example DataData

Derivation of chronic and acute Natural Derivation of chronic and acute Natural StandardStandard

0

1

2

3

4

5

6

0 10 20 30 40 50 60

Copper Concentration (µg/L)

Fre

qu

ency

Acute standard: 90th percentile

Chronic standard: the mean

Page 41: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

41

Statistical Characterization Statistical Characterization ApproachApproach

Calculating Permit LimitsCalculating Permit Limits Calculating permit limits is described in the Calculating permit limits is described in the

EPA’s permit manual for Toxics. EPA’s permit manual for Toxics. Permits require calculation of wasteload Permits require calculation of wasteload

allocation , long term average, average allocation , long term average, average monthly load, and maximum daily load.monthly load, and maximum daily load.

The values calculated for the Natural The values calculated for the Natural Standards statistics are used to calculate Standards statistics are used to calculate these types of permit limits. these types of permit limits.

Page 42: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

42

Statistical Characterization Statistical Characterization ApproachApproach

Other Water ActionsOther Water Actions Natural Standards calculated by statistical Natural Standards calculated by statistical

characterization can also be used for :characterization can also be used for : Determining if a waterbody is impaired or Determining if a waterbody is impaired or

meeting standards under the Clean Water Act meeting standards under the Clean Water Act Section 303(d); or Section 303(d); or

Determining waterbody recovery goals in a Total Determining waterbody recovery goals in a Total Maximum Daily Load plans for impaired Maximum Daily Load plans for impaired waterbodies.waterbodies.

Page 43: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

43

For More InformationFor More Information

Call Jim Powell at 907- 451-Call Jim Powell at 907- 451-28812881

Or use the DEC websiteOr use the DEC websitewww.dec.state.ak.us/water/wqsar/trireview/naturawww.dec.state.ak.us/water/wqsar/trireview/naturalconditionslconditions

Page 44: 1 Alaska Department of Environmental Conservation Division of Water, Water Quality Standards Program Proposed Water Quality Standard for Natural Conditions.

44

Question and AnswersQuestion and Answers