EPA Office of Water, Washington, DC. TMDL Program Results Analysis Fact Sheet # EPA841-F-09-004, December 2009
Fact Sheet: Summary of EPA's '100 TMDLs Review'
Why the need for a review of TMDLs?
Total Maximum Daily Loads (TMDLs) are key elements of the Clean Water Act approach to restore and maintain impaired waters. In the past, many outside
efforts have analyzed the status of the TMDL program. These included a 2001 report by the National Research Council (NRC) called "Assessing the TMDL
Approach to Water Quality Management" as well as a review of 100 TMDL documents by the Water Environment Research Federation (WERF) in their 2003
report: "Navigating the TMDL Process: Evaluation and Improvements." The EPA conducted an internal review of 100 TMDL documents in 2005 to assess the
status of the TMDL program and analyze the content and qualities of TMDLs being produced across the nation.
Review methods
This national study selected ten TMDL reports from each of EPA's ten regional offices for a total of 100 documents for review. These documents encompassed
492 TMDLs from 47 states. In order to represent current practices as well as a comprehensive selection of EPA regions and states, the TMDLs were selected
from those approved since January 1, 2004, except as necessary to include as many states as possible. The following elements of EPA's TMDL Checklist,1
along with a few additional characteristics, provided the framework for the review and its findings summarized below:
Elements Reviewed
Submittal Letter
Identification of Waterbody, Pollutant of Concern
Applicable Water Quality Standards
Loading Capacity
Load Allocations (LAs)
Waste Load Allocations (WLAs)
Margin of Safety (MOS)
Consideration of Seasonal Variation
Reasonable Assurances for Point
Sources/Nonpoint Sources
Public Participation
Technical Analysis
EPA entry into the National TMDL Tracking System
(NTTS)
Model Use
Follow-up Monitoring
Implementation Plan
Reduction Allocations
Developed under legal obligation?
Not reviewed
Reviewed
Reviewed
Reviewed
Reviewed
Reviewed
Reviewed
Reviewed
Reviewed
Reviewed
Not reviewed
Reviewed
Reviewed
Reviewed
Reviewed
Reviewed
Reviewed
What we learned, at a glance...
Mixed PS/NPS TMDLs 57%; NFS-only 41%; PS-only 2%
76% of TMDLs were written to numeric standards and 24% to
narrative standards
30% of TMDLs refined their LA into more than one category (on
average 5 categories)
100% of TMDLs had an MOS: 58% exolicit MOS: 32% imolicit MOS
98% of all TMDLs considered seasonal variation
83% of all TMDLs, and 93% of PS/NPS TMDLs, addressed
reasonable assurances
41% of TMDLs had more than one public meeting and/or
opportunity for stakeholder involvement in TMDL development
95% of PS and PS/NPS TMDLs included permit #'s in either the
TMDL document or in NTTS
79% mentioned follow-up monitoring specific to the watershed
66% of TMDLs included some form of an implementation plan;
34% of TMDLs included a plan with targets and milestones
1 USEPA (1992) Guidelines for Reviewing TMDLs under Existing Regulations. Found at: http://www.epa.qov/owow/tmdl/quidance/final52002.html
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EPA Office of Water, Washington, DC. TMDL Program Results Analysis Fact Sheet # EPA841-F-09-004, December 2009
Comparison of Pollutants identified in the 100 TMDLs Review vs. the TMDL "Universe"
The 100 TMDLs review captured over 95% of the pollutant types for which TMDLs were developed as of 2005. The table below compares pollutants identified
in the 100 TMDL Review versus pollutants represented in all TMDLs entered into EPA's National TMDL Tracking System (NTTS) as of the review date.
Pollutant
Pathogens
Nutrients/BOD/Dissolved Oxygen/Algal
Pesticides (incl. DDT)
Tu rb idity/Sed iment/TSS
pH
Thermal modifications
Metals (not incl. Mercury)
PCBs
Mercury
Cond ucti vity/TDS/Ch lorid es
Chlorine
Sulfates
Unionized ammonia
Noxious aquatic plants
TMDL Review
36%
20%
11%
9%
6%
5%
4%
3%
3%
<2%
<1%
<1%
<0.5%
<0.5%
Recent TMDLs
25%
14%
4%
9%
2.7%
6%
12%
1.0%
1.3%
6%
1.2%
12%
2.5%
0.1%
Comparison of Findings on Load Reduction Allocations.
Reductions allocations
Only PS TMDLs: PS reduced
Only NPS TMDLs: NPS
reduced
PS/NPS: NPS load reduced
PS/NPS: PS loads reduced
PS/NPS: Both loads reduced
No allocations made; no
load reductions required;
or indeterminate
100 TMDLs Review
2%*
38%
15%**
1%
39%
4%
WERF Review
8%
26%
16%
5%
23%
22%
"it is unclear whether the single PS only TMDLs in our study received reductions. They
could potentially belong in the bottom category.
"Half of this number are TMDLs that received reductions for NPS & Stormwater but not for
non-stormwater ooint sources.
Summary of Comparison
Over 95% of Impairment Causes were covered in the 100 TMDLs
Review
Impairment Causes unrepresented in the 100 TMDLs Review
(less than 5% of the total TMDLs in NTTS as of 2005):
• Unknown toxicity 0.2%; Biocriteria/ALU/General WQS (Benthic)
1.1%; Other inorganics 1.1%; Priority & nonpriority organics
0.8%; Habitat 0.8%; Total dissolved gas & volatile solids 0.6%;
Radiation 0.2%; Taste & Odor 0.1%; Cyanide 0.02%
Underrepresented Impairment Causes:
• Metals, sulfates, conductivity/TDS/chlorides
Overrepresented Impairment Causes:
- Pathogens, nutrients, pesticides
Other Notable Observations
I
>*•
>
79% incorporated critical conditions into the TMDL
calculation
18% of TMDLs described as phased TMDLs
6% of TMDLs allocate for future growth
15 documents had allocations as concentrations
4 documents had only % reductions as load/wasteload
allocation
89% of TMDLs appeared in documents containing more
than 1 TMDL
Model complexity: 43% low; 24% medium; and 22% high
Significant stakeholder involvement found in 40% of
TMDLs, most often in watershed TMDLs
78% of TMDLs calculated the existing load (86 documents)
For more information about TMDLs, visit TMDL Home http://vwvw.epa.qov/owow/tmdl/ or the TMDL Program Results Analysis Page http://www.epa.gov/owow/tmdl/results/
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