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Jason Sutter Hydrologist Verde Watershed Association Meeting January 19, 2005

Total Maximum Daily Load (TMDL) Unit Hydrologic Support and Assessment Section Water Quality Division Arizona Department of Environmental Quality. Jason Sutter Hydrologist Verde Watershed Association Meeting January 19, 2005. What is a TMDL?.

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Jason Sutter Hydrologist Verde Watershed Association Meeting January 19, 2005

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  1. Total Maximum Daily Load (TMDL) UnitHydrologic Support and Assessment SectionWater Quality DivisionArizona Department of Environmental Quality Jason Sutter Hydrologist Verde Watershed Association Meeting January 19, 2005

  2. What is a TMDL? • The maximum amount (load) of a water quality parameter which can be carried by a waterbody without causing an exceedance of surface water quality standards • It is calculated as the sum of load allocations (LAs) plus waste load allocations (WLAs) plus a margain of safety (MOS) TMDL= ∑LA + ∑WLA + MOS

  3. Water quality monitoring for TMDL purposes is designed to identify sources and critical conditions for loading • Once calculated, a TMDL is used to determine necessary load reductions needed to meet water quality standards • An implementation plan is then developed to improve water quality by reducing loading to the waterbody

  4. Why develop a TMDL? • ADEQ produces the 305(b) Water Quality Assessment Report which describes the status of surface and groundwater resources every two years • The report fulfills requirements of the Clean Water Act • A list (303d) of Arizona’s impaired waters is produced and prioritized for TMDL development

  5. Past Verde Watershed TMDL Activities • Oak Creek Nutrient and Phosphorus TMDL- 1999 • Slide Rock Pathogen TMDL- 1999 • Peck’s Lake Nutrient TMDL- 2000 • Stoneman Lake Nutrient TMDL- 2000 • Verde River Assimilative Capacity Study- 2001 • Verde River Turbidity TMDL- 2002

  6. Current TMDL Activities • Oak Creek Pathogen TMDL Phase II • Beaver Creek Targeted Monitoring • Whitehorse Lake Dissolved Oxygen TMDL

  7. Oak Creek Pathogen TMDL Phase II • Standard is based on colony forming units per 100 ml (cfu/100ml) Escherichia coli (E. coli) as an indicator of other possible pathogens • Single Sample maximum • 235 cfu/100ml (580 cfu/100ml- 1999) • Geometric mean (4 sample minimum) • 126 cfu/100ml (130 cfu/100ml- 1999)

  8. Objectives of Phase II Study • Determine critical conditions that result in WQ exceedances • Extent of exceedances • Identify sources/source areas • Calculate pollutant loads and allocations • Collect sufficient data to allow for effective BMPs to be identified and initiated

  9. Preliminary Results • Winter baseflow (23 sites) Water column samples (cfu/100ml): • Range: 0-47.9 • Average: 9.6 Sediment samples (cfu/g of wetted sediment): • Range: 0-14.5 • Average: 5.6

  10. Winter Storm Runoff Water column samples (cfu/100ml): • Range: 16.66- 365.4 • Average: 127 Sediment samples (cfu/g of wetted sediment): • Range: 0.27- 15.74 • Average: 5.79

  11. High Visitation Sampling • Sampled 10-15 sites twice a day over Memorial and Labor Day weekends 2004 • No widespread exceedances, Slide Rock State Park did not sample • Labor Day results were consistently higher than Memorial Day • Trend shows that morning samples were higher than afternoon

  12. Future Sampling Activities • Additional winter storm runoff • Spring runoff • Intensive July 4th weekend • Summer baseline • Possible further DNA studies

  13. Verde Assimilative Capacity • Designed to determine what capacity the Verde had available to handle additional nutrient loads expected with continued growth • Modeling showed that Verde was able to meet water quality standards with projected growth through 2030 with a small increase in the frequency of exceedances upstream of Clarkdale

  14. Significant Assumptions • Potential impact of increased development in the Little Chino Valley and its affect on groundwater discharges to headwaters • Transport of nutrient loads from wastewater discharges to dry washes

  15. Additional Studies • USGS is currently working on groundwater model for Big and Little Chino Valleys, includes additional water quality monitoring • ADEQ is in the process of determining how to use additional data to rerun model • Model rerun will be used in deciding if additional targeted monitoring is needed

  16. Contact Information Jason Sutter, Hydrologist 602-771-4539 sutter.jason@azdeq.gov Nancy LaMascus, TMDL Unit Supervisor 602-771-4468 cnl@azdeq.gov www.azdeq.gov/environ/water/assessment/tmdl.html

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