Nutrient Limits:

What to Expect

Water Division Arkansas Department of Environmental Quality

wentz@adeq.state.ar.us bailey@adeq.state.ar.us

• 1998 EPA published the National Strategy for the

Development of Regional Nutrient Criteria (National Strategy)

• 2000 EPA published Nutrient Criteria Technical Guidance Manual: Rivers and Streams

• 2001 EPA published recommended, regional numeric

nutrient criteria for rivers and streams under section 304(a) of the Clean Water Act (66 FR 1671).

Timeline of Nutrient Criteria Development

Timeline of Nutrient Criteria Development

• 2001 EPA requested each state and authorized tribe to

develop a Nutrient Criteria Development Plan

• 2004 ADEQ updated Reg. 2.509 Nutrients

Materials stimulating algal growth shall not be present in concentrations sufficient to cause objectionable algal densities or other nuisance aquatic vegetation or otherwise impair any designated use of the waterbody. Because nutrient concentrations do not always correlate directly with stream impairments, impairments will be assessed by a combination of factors such as water clarity, dissolved oxygen, pH, aquatic-life community structure and possibly others.

Timeline of Nutrient Criteria Development

EPA Guidance for Criteria Development

Approach 1 Use reference stream conditions -Assumes a large portion of streams are impaired

Approach 2 Predictive models -Difficult to replicate across ecoregions

Approach 3 Established nutrient thresholds, biocriteria, and stressor-response relationships -Most defensible

• 2000 EPA Nutrient Criteria Technical Guidance Manual: Rivers and Streams

EPA Guidance for Criteria Development

Approach 1 • Set criteria at 25th percentile of all data OR 75th percentile of reference streams

• More involved, based on reference conditions, preferred method • Difficult to define least-disturbed conditions, thus use <25th

percentile as least-disturbed

- Nutrient Concentration +

Approach 3 (Development of Biocriteria) • Based on the assumption that as nutrient concentrations increase,

certain biological assemblages will be negatively impacted

• Develop Nutrient Index of Biotic Integrity (N-IBI)

• Allow ADEQ scientists to identify any potential relationships between nutrient concentrations and biotic assemblages • If relationships exists, ADEQ scientists will then attempt

to determine at what point biotic assemblages are negatively impacted (thresholds)

• These thresholds can be used to set numeric

criteria along with values from Approach 1

EPA Guidance for Criteria Development

Approach 3 (Concept of Stressor-Response)

Approach 3 (Concept of Stressor-Response)

Approach 3 (Hypothetical Stressor-Response)

• Lakes/Reservoirs

– Pilot Project – Beaver Lake

• Growing season geometric mean chlorophyll a – 8 ug/L

– Secchi depth 1.1m

- Type B and C Lakes

• Rivers/Streams

– Pilot Project – Upper Saline River Watershed

– Ozark ERW

Nutrient Criteria Development

(B) Site Specific Nutrient Criteria Lake Chl a (ug/L)** Secchi (m)*** Beaver Lake* 8 1.1 * These criteria are for measurement at the Hickory Creek site over the old

thalweg, below the confluence of War Eagle Creek and the White River in Beaver Lake. ** Growing season geometric mean (May – October) *** Annual Average

Reg. 2.509 Nutrients

Classification and Validation of Nutrient Criteria within the Ozark Highlands ERWs

Task 1

Historical Data Compilation and Site Selection

Task 2 Data Collection Subtask 2.1

Water Quality Assessments Anticipated time frame: 2013 & 2014

• A minimum of twelve collections made over two years • Collect in-situ parameters during each site visit • Water chemistry

• Total Kjeldahl Nitrogen (TKN), total organic carbon (TOC), ammonia nitrogen (NH4-N), total dissolved solids (TDS), Nitrite + Nitrate Nitrogen (NO2+NO3-N), turbidity, total phosphorus, total, nitrogen, total suspended solids (TSS), orthophosphorus, and metals

• Diurnal dissolved oxygen assessments • Deploy continuous read meters twice during critical season

Task 2 Data Collection Subtask 2.2

Macroinvertebrate Assemblage Assessment Anticipated time frame: Spring (February-April) 2013 & 2014

• Collect using five-minute traveling kick methodologies described in ADEQs macroinvertebrate SOP

Subtask 2.3

Periphyton Assemblage Assessment Anticipated time frame: Spring, Summer 2013 & 2014

Ash Free Dry Mass (AFDM) and Chlorophyll a -Periphyton assemblages will be sampled following surface area methods. A quantitative algal subsample will be collected from ten randomly selected cobbles at each riffle location.

Ozark Highlands

5th 25th 75th* EPA 2001

Total Nitrogen (mg/L)

0.30 0.60 0.62 0.31

Total Phosphorus (mg/L) 0.02 0.03 0.06 0.01

Approach 1

*75th percentiles calculated from least-disturbed streams

ERWs

5th 25th 50th 75th EPA 2001

Total Nitrogen (mg/L)

0.10 0.36 0.57 0.84 0.31

Total Phosphorus (mg/L) 0.02 0.03 0.04 0.06 0.01

Status of Nutrients Across the Country

As of 2008* - 7 states have adopted numeric criteria for one or more

parameters for at least one entire waterbody

- 18 states adopted numeric criteria for one or more parameter for select individual waters

- Arkansas proposed Beaver Lake criteria in 2010

- 25 states have not adopted any numeric criteria

*EPA-821-F-08-007 State Adoption of Numeric Nutrient Standards (1998-2008)

What does all this mean?

Permit Limits based defensible science Currently use Reg 2.509 As well as location, i.e. Nutrient Surplus Area

Reg. 2.509 Nutrients

Will I get a new limit?

“To protect, enhance, and restore the natural environment for the well-being of all Arkansans.”