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Introduction to TMDLs for Nutrients. Presented by: Dr. Scott Emery January 15, 2009. Total Maximum Daily Load (TMDL). The maximum loading of a pollutant that can be discharged in a surface water and still meet its designated use and water quality standards.
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Introduction to TMDLs for Nutrients Presented by: Dr. Scott EmeryJanuary 15, 2009
Total Maximum Daily Load(TMDL) The maximum loading of a pollutant that can be discharged in a surface water and still meet its designated use and water quality standards. Not meeting its TMDL = Impaired
Why TMDLs? • Section 303(d) Clean Water Act (USEPA) • Section 403.067 Florida Statutes (Florida Watershed Restoration Act) • Chapter 62-303 Florida Administrative Code (Identification of Impaired Surface Waters)
States Must: • Identify impaired water bodies or segments • Develop TMDLs • Implement programs to eliminate the impairment
Nitrogen and Nutrient Impairment Rule 62-302.300 FAC, subsection 13: highlights excessive nutrients (e.g. nitrogen and phosphorus) as “one of the most severe water quality problems facing the state.” Statewide, nutrient impairment is the single largest category (others include bacteria, metals). Multiple water bodies and segments within Hillsborough County are involved in the TMDL issue.
Nitrogen is a major pollutant of concern in Tampa Bay • Excess nitrogen clouds the water and reduces sunlight so seagrasses can’t grow. • Baywide, residential runoff accounts for 20% of the total nitrogen load to Tampa Bay
Components of a TMDL TMDL = WLA Wasteload Allocation For Point Sources + LA Load Allocation For non-Point sources (incl. background) + MOS Margin of Safety
Source Type Examples of Point Sources • Domestic wastewater treatment facilities • Industrial wastewater treatment facilities • Urban stormwater discharges from larger master drainage systems • Some construction site stormwater • Some industrial site stormwater • Some animal feeding operations Examples of Non-point Sources • Septic tanks • Some types of urban/suburban/rural run-off • Agricultural run-off • Forestry • Mining • Mismanagement of household pesticides, yard trash, fertilizers, etc.
Compliance Strategy For each impaired water body/segment (WBID), for each type of impairment, a Basin Management Action Plan (BMAP) must be developed Requires definitive commitments from stakeholders, including the County. Meeting these TMDLs will, in all likelihood, require substantial money from the County to implement projects and programs. ( )
Costs to remove nitrogen from surface waters Costs to remove excess nitrogen from waterways can be significant. Stormwater retrofits can range from $40,000-$200,000 per ton (SWFWMD). Wastewater treatment upgrades are greater than that amount.
Fertilizer Management Fertilizer use is one possible source of nutrients (nitrogen and phosphorus) and FDEP has listed (FDEP 2005) the mismanagement of fertilizers as a possible non-point source of pollution.
Estimated Nitrogen Reductions from 50% Compliance with Fertilizer Management Ordinance
HILLSBOROUGH COUNTY PUBLIC WORKS DEPARTMENT EXAMPLE NITROGEN-REDUCTION PROJECTS & COSTS * CDS – Continuous Deflective Separation unit used to separate solids from stormwater. Sediment and other solids along with associated other pollutants such as some nutrients and heavy metals are separated from the stormwater and collected in the unit. ** Stormceptor – Another type of unit used to separate solids from stormwater. Prepared January 14, 2009 - HCPWD
