1 / 12

Vicki Conway January 19, 2005

Are Current “Adaptive” TMDLs Really Adaptive?. Vicki Conway January 19, 2005. SANITATION DISTRICTS OF LOS ANGELES COUNTY. Adaptive TMDLs…NOT. If it looks like a duck and quacks like a duck, it may not always be an adaptive duck in the TMDL world.

ghazi
Télécharger la présentation

Vicki Conway January 19, 2005

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Are Current “Adaptive” TMDLs Really Adaptive? Vicki Conway January 19, 2005 SANITATION DISTRICTS OF LOS ANGELES COUNTY

  2. Adaptive TMDLs…NOT If it looks like a duck and quacks like a duck, it may not always be an adaptive duck in the TMDL world.

  3. NRC Definition of “Adaptive Implementation” of TMDLs “It is a process of taking actions of limited scope commensurate with available data and information to continuously improve our understanding of a problem and its solutions, while at the same time making progress toward attaining a water quality standard.”

  4. At First Glance • Many LARWQCB (Region 4) TMDLs appear to be adaptive • Implementation plans include: • Special scientific studies • Reopeners - Regional Board considers a Basin Plan Amendment for site-specific objectives or reconsiders WLA for specific constituents based on studies

  5. At First Glance • Features that are not adaptive • MOS: explicit margin of safety of 10 percent and an additional implicit margin of safety is incorporated through conservative model assumptions and statistical analysis. • Seasonal variations and critical conditions are prescriptive regardless of basis of WQO.

  6. Case Study: Upper Santa Clara River Chloride TMDL • Objective of 100 mg/L scientifically questionable • Based on antidegradation • Coincidentally represents lowest chloride level of UC Coop Extension guidelines for irrigation water for salt sensitive crops (via leaf exposure) • Historical variations in surface water and groundwater quality • Seasonal variations related to droughts and changes in water supply • Existing use questionable • Approx. 35 acres avocado crops grown • No evidence of impacts on agriculture

  7. Adaptive Elements in the Upper SCR Chloride TMDL - Studies • Chloride Source Identification/Reduction, Pollution Prevention and Public Outreach Plan • Groundwater/Surface Water Interaction Model (Year 2 of 13) • Evaluation of Appropriate Chloride Threshold for the Protection of Sensitive Agriculture (Year 3 of 13) • Evaluation of Appropriate Chloride Threshold for Endangered Species Protection (Year 3 of 13) • Development of Site Specific Objectives for Chloride (including an ADA) (Year 4 of 13)

  8. Adaptive Elements in the Upper SCR Chloride TMDL - Reopeners • Re-evaluate schedule for agricultural chloride threshold study (Year 1 of 13) • Reconsideration of action taken on final WLA (Year 5 of 13) • Re-evaluation of Schedule to implement Chloride Control Measures (Year 9 of 13)

  9. Why These Are Not Truly Adaptive… • Science is being driven by the schedule • May result in a higher level of uncertainty, and therefore a larger MOS • Agricultural studies • Literature review vs. Lab studies vs. Field studies • Osmotic effects vs. Ion Specific Effects • Groundwater/Surface Water Interaction Model • Public Domain vs. Proprietary Software- constrained to use certain models • Aquatic life studies • Testing/evaluating surrogates of ES

  10. Why These Are Not Truly Adaptive… • No potential for feedback based on actions taken to reduce chloride loads • Self Regenerating Water Softeners (SRWS) will reach the end of their service life and chloride levels will then decrease • Due to prohibition of installation of new SRWS, population growth will result in lower chloride levels from POTW’s

  11. Why These Are Not Truly Adaptive… • Lack of Political Will to Revise WLA’s and/or Water Quality Objectives • No relaxation of water quality standards, regardless of what the science is telling you • In 2000, two attempts to revise the Chloride WQO failed • First draft of the SCR Chloride TMDL was proposed in 2002. Since then there has been several versions, several remands, and a settlement agreement • TMDL is expected to become effective in the near future.

  12. Consequence of Upper SCR Chloride TMDL • Requires expenditure of millions of dollars to conduct all special studies in parallel • Final WLA are included in TMDL – likely difficult to change and will be applied as end-of-pipe limits • May result in having to design, construct and operate advanced treatment systems prior to scientific questions regarding chloride threshold being answered • Only time will tell whether or not the TMDLs are truly adaptive

More Related