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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
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
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
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
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
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
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%)
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
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)
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
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
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
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
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)
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?
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