nutrient criteria for streams and rivers
TRANSCRIPT
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Nutrient Criteria for Streams and Rivers
EPA Framework for Nutrient Reduction
Texas Water Conservation Association
Water Quality Subcommittee
October 13, 2011
Jim Davenport
WQ Monitoring & Assessment Section
WQ Planning Division
Office of Water, TCEQ
Tel. 512/239-4585
Pedernales River
Image by: Texas Water Development Board
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TCEQ Nutrient Criteria: Development
Submitted plans to EPA in 2001, 2006
Reservoirs, then streams & estuaries
Convened advisory workgroup
Based on data for each reservoir
Proposed for 93 reservoirs
- Stand-alone Chl a criteria
- Chl a criteria, + screening levels:
TP, transparency
Adopted for Chl a for 75 reservoirs, 6/30/10
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EPA Review
WQ Standards
• Adopted by TCEQ - 6/30/2010
• Additional documentation to EPA - 8/4/2011
• EPA request for more information regarding
nutrient criteria - 5/17/2011
Standards Implementation Procedures
• Approved by TCEQ 6/30/2010
• Comments from EPA 12/2/2010 letter
Lake Bridgeport
Image by: TRWD
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Summary of Current Plans
Develop criteria option for selected rivers and estuaries based on historical conditions
- Individual water bodies
- Reference groupings
Develop criteria option for streams and rivers based on stressor/response analyses
Initiate additional options for estuaries based on ongoing efforts (e.g., stressor/response)
Revisit reservoir criteria
Consider ways to incorporate weight-of-evidence
Develop implementation options
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Why Are Nutrient Criteria Difficult?
Lack of clear “use-based” thresholds for uses such as recreation & aesthetics, aquatic life propagation, drinking water sources
Responses to nutrients are highly variable –e.g., effect of TN and TP on Chl a
No consensus on how to derive criteria
Independent criteria or “weight-of evidence”?
Insufficiencies in historical monitoring data
Initial EPA guidance criteria were problematic
High concern about regulatory impacts
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Streams & Rivers: Challenges
Limited data for TN and relative abundance ofattached algae
Regional, hydrologic, chemical variability
Grouping streams and rivers
Parameters? TP, TN, Chl a, % cover …
Weight-of-evidence – Development, Assessment
Effluent-dominated streams / attainability
Reasonable implementation
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Tx Streams: Instream Dilution
For 358 major domestic discharges:
% effluent instream at 7Q2 No. of discharges
0 - 25% 57 (16%)
26 - 50% 32 ( 9%)
51 - 75% 47 (13%)
76 - 99% 122 (34%)
100% 100 (28%)
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Available Data – Streams and Rivers
30-40 years of data at 100’s of stations, for TP, ~TN, Chl a, Transparency, D.O., etc. plus frequent fish, invertebrate sampling
Data and Research Needs• Algae Sampling – attached periphyton sampling
• Representative Stations
• More TN data
• Lower TP and TN detection limits
Recent Stream and River Projects • Regional nutrient sampling studies of streams
• Statistical responses to N & P – historical data
• Peer review of other states, prognosis for Texas
• Additional studies
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The Road Ahead: Streams & Rivers
Categorize and group based on
Geography?
Hydrology?
Chemical similarities?
Option 1: Base criteria on historical levels in reference streams and rivers
Option 2: Stressor/response analyses, relating TN,TP to biological indices, D.O., Chl a (in rivers), attached algae (smaller streams)
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EPA Framework for State Nutrient
Reductions
EPA Memo from Nancy Stoner, 3/16/2011
Summarizes 8 key elements needed for state programs to reduce nutrient loadings
Intended as a flexible planning tool
Left: Water Jets
Image by: CSTARS
Right: A Texas Estuary
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Prioritize watersheds on a statewide basis
Set watershed load reduction goals
Ensure effectiveness of point source permits
Agricultural areas
Storm water and septic systems
Accountability and verification measures
Annual public reporting of implementation activities
& biannual reporting of load reductions
Develop work plan, schedule for numeric criteria
EPA Framework for State Nutrient
Reductions: Eight Key Elements
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Recent Activities
3/10/11 EPA (Jackson) addresses U.S. House Committee on Ag, re: nutrient criteria
3/16/11 EPA memo on nutrient framework
5/24/11 EPA VI requests responses to memo
6/23/11 ASIWPCA letter, urging flexibility for framework, “weight-of-evidence” for criteria
8/23/11 TCEQ provides initial response to memo
10/4/11 U.S. Senate subcommittee on nutrients
10/5/11 States meet with EPA on flexibility & weight of evidence for nutrient criteria
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EPA Nutrient Framework
Initial TCEQ Response (8/23/11)
TCEQ is already implementing many elements:
- Reservoir nutrient criteria, continuing efforts
- New standards implementation procedures
- Watershed efforts by TCEQ and TSSWCB
- Increased studies, monitoring efforts
Resource/regulatory impact concerns
- Texas has ~ 210 8-digit HUC watersheds
TCEQ amenable to discussion with EPA
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2010 Nutrient Implementation Procedures
In 2010 Standards Implementation Procedures
Applied to increases in domestic discharges
Sets framework for nutrient (TP) effluent limits
Reservoirs – predict effects on “main pool”
Reservoirs – assess local impacts
- Apply site-specific screening factors
- Level of concern – low, moderate, or high
- Assess “weight-of-evidence”
Streams – assess local impacts (as for reservoirs)
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Nutrient Criteria & Management
Concluding Notes
• EPA review of 2010 nutrient criteria continues
• Focus of options for stream nutrient criteria:
- Historical reference conditions
- Observed responses to N & P (existing data)
- Incorporating “weight of evidence”
- Flexibility for implementation
• Discussions on EPA framework are pending
• Questions / Comments?