Total Maximum Daily Load (TMDL) Cara Cowan Watts Graduate Student Biosystems Engineering

Source of Class Materials Presentations and Handouts adapted from The U.S. EPA’s Water Quality Standards Academy November 27-December 1, 2006 Washington, DC

Total Maximum Daily Load (TMDL) Strategy for achieving WQS 303(d) Process Based on the relationship between pollutant sources and the condition of a water body Describes an allowable pollutant load and allocates it among several sources

Pollutant Dredged spoil Solid waste Incinerator residue Filter backwash Sewage sludge Munitions Chemical wastes Biological materials Cellar dirt Sand (Some) radioactive materials Heat Wrecked or discarded equipment, Rock Industrial, municipal, and agricultural waste discharged into water

TMDLs Amount of specific pollutant a waterbody can receive and assimilate to still meet water quality standards States and tribes are required to develop TMDLs for waters on their 303(d) lists TMDLs are approved or disapproved by EPA IF disapproved, EPA develops the TMDL

TMDL Components Allowable pollutant load (cap) Allocation of cap among sources Margin of safety (MOS) TMDL = ΣSWLAi + ΣSLAi + MOS ΣSWLAi: Sum of waste load allocations (point sources) ΣSLAi: Sum of load allocations (nonpoint sources) MOS Extra measure of protection due to uncertainty Can be explicit (percentage) or implicit (safety factors and assumptions in modeling)

Components of TMDL Wasteload allocations (WLAs) assigned to each point source Load allocations (LAs) assigned to nonpoint sources WLAs and LAs established so predicted receiving water concentrations do not exceed water quality criteria Other Loads (Nonpoint Background) Reserve Capacity Point Source #1 #2 #3 #4

TMDL “Caps” For specific pollutants For pollutant indicators Sediment, nitrogen, phosphorus, temperature, copper, mercury, etc. For pollutant indicators Biochemical Oxygen Demand (BOD) Chemical Oxygen Demand (COD) Not necessarily daily Weekly, monthly or yearly May vary seasonally

TMDL Allocations Each point source with individual NPDES permit receives a wasteload allocation (WLA) Point sources covered under general permits can also get a wasteload allocation (WLA) Individual sources, categories, subcategories of nonpoint sources are represented by a load allocation (LA) No EPA rules on how to allocate

NPS Source Category 2 (LA) NPS Source Category 1 (LA) TMDL Allocation Sub Watershed 1 MOS Reserve Capacity Sub Watershed 2 Natural Background Point Source 1 (WLA) NPS Source Category 2 (LA) NPS Source Category 1 (LA) Point Source 2 (WLA)

TMDL Pollutants Completed TMDL Review Recent TMDLs Pathogens 36% 25% Nutrients/BOD/Dissolved Oxygen/Algal 20% 14% Pesticides (incl. DDT) 11% 4% Turbidity/Sediment/TSS 9% pH 6% 2.7% Thermal modifications 5% Metals (not incl. Mercury) 12% PCBs 3% 1.0% Mercury 1.3% Conductivity/TDS/Chlorides <2% Chlorine <1% 1.2% Sulfates Unionized ammonia <0.5% 2.5% Noxious aquatic plants 0.1%

Load Calculations & Reductions 78% of TMDLs calculate existing load even though not required by regulations Reductions range from 0 to 100% Pathogen TMDLs most often require very high percent reductions 30% of TMDLs refine LA into more than one category Up to 18 subcategories (median = 3)

“319” Programs Available to states, territories and tribes 40% “state” match required (dollars and/or in-kind) EPA allocation formula population, farmland, water quality problems, etc In FY06, Congress appropriated $204 million Down from high of $238 in ’02

319 Grant Opportunities 104.6 Dollars (Millions) 21.9 18.2 17.5 Type of Activity

$100M “310” Funds Incremental Cannot use for on-the-ground BMP implementation until Watershed plan developed Show how BMPs fit into that plan “Waivable ceiling” of 20% of incremental funds can be used to develop watershed plans

Load Reduction Impact Trends Reductions allocations TMDL Review Only PS TMDL, PS reduced 2%* Only NPS TMDL, NPS reduced 38% PS/NPS, NPS load reduced 15%** PS/NPS, PS load reduced 1% PS/NPS, Both loads reduced 39% No allocations made; no load reductions required; or indeterminate 4%

Questions?