2022 – 2024 LOADING ESTIMATES

Dr. Marcus Beck,

Tampa Bay Estuary Program

Dr. Ray Pribble,

Environmental Science Associates

Dec 9, 2025

RA FRAMEWORK

  • Each year, assess attainment of water quality thresholds
  • Loadings only evaluated if water quality thresholds not attained in two consecutive years
  • Annual reporting to FDEP, fourth year of 2022 – 2026 RA period

EPA TMDL

Based on 1992 – 1994 mean loads:

  • OTB: 486 tons / yr
  • HB: 1451 tons / yr
  • MTB: 799 tons / yr
  • LTB: 349 tons / yr
  • RALTB: 629 tons / yr

2022 – 2024 LOADING ESTIMATES

  • Calculated with 2023 land use data, current precipitation/atmospheric data, partner-provided data
  • Described as total loads broken down by source categories:
    • Atmospheric deposition
    • Domestic point sources: end-of-pipe, reuse
    • Industrial point sources (including material losses)
    • Nonpoint sources
    • Groundwater/Springs
  • Entity allocations for domestic, industrial, and nonpoint sources, by bay segment

TOTAL LOADS BY SEGMENT

TOTAL LOADS BY SEGMENT

TOTAL LOADS BY SEGMENT

EPA TMDL

Hydrologic normalization for Nitrogen Delivery Ratio:

  • OTB: 1.08 tons / mill m3 water
  • HB: 1.62 tons / mill m3 water
  • MTB: 1.24 tons / mill m3 water
  • LTB: 0.97 tons / mill m3 water
  • RALTB: 1.59 tons / mill m3 water

NITROGEN DELIVERY RATIOS

NITROGEN DELIVERY RATIOS

LOADS BY SOURCE

LOADS BY SOURCE

PROPORTIONAL 2022 – 2024

PROPORTIONAL 2022 – 2024

HYDROLOGIC LOADS

HYDROLOGIC LOADS

HYDROLOGIC LOADS JUN – SEP

NPS BY MONTH 2022 – 2024

NPS BY MONTH 2022 – 2024

TABLE SUMMARY

* No TMDL

CONCLUSIONS

  • Chlorophyll-a thresholds attained for first three years of 2022 – 2026 RA period
  • No need to evaluate loadings – but, absolute load exceeded for OTB and RALTB in 2022, all segments except LTB in 2024
  • High loadings in 2024 from tropical storm activity, NPS contributions
  • Nitrogen delivery ratio not exceeded in any segment for 2022 – 2024