1999 U.S. EPA Ammonia Criteria Technical Review Update

1. 1999 U.S. EPA Ammonia CriteriaTechnical Review Update Basic Standards Workgroup September 10, 2004 Prepared by: Chadwick Ecological Consultants, Inc.

2. Ammonia Criteria Review • What we found and how we got there • Review conducted on behalf of Colorado Wastewater Utility Council • Completed earlier analysis last fall • We suggested new approaches • Maybe too “radical” • Back to more straightforward approach • Council suggested we simply update EPA equations based on our: • Literature review results • Data quality review

3. Derivation of Revised Criteria • Technical Review • Analysis of data used/not used by EPA • Analysis of data analysis approaches • Literature review for any new data • There are lots of new data • EPA did not conduct formal literature review for 1999 update • Reanalysis of criteria – different approaches? • Preliminary Results • Review generally supports 1999 criteria “as is” • But could update with new data/approaches

4. Updated EPA acute database • Evaluate existing studies for appropriate use in deriving numerical water quality criteria • Data quality review – some bad datapoints, some odd decisions • Removed > or < LC50 values from database • Updated EPA acute toxicity database • Literature review results • Added 15 genera to the 34 in database (49 total)

5. Updated database, continued • Recalculate SMAV and GMAV based on pH8 normalized data • Could not specifically verify “with and without salmonid” derivation used by EPA • Recommend “warm and cold” instead • More supportable and representative • Simply split dataset based on habitat types (i.e., cold water and warm water)

6. Final Acute Value (FAV) for the Cold Water database • Four most sensitive genera • Prosopium (12.1 mg TA-N/L) • Ceriodaphnia (14.2 mg TA-N/L) • Oncorhynchus (20.0 mg TA-N/L) • Salmo (23.7 mg TA-N/L) • FAV = 13.3 mg TA-N/L • Did not override the FAV with “large” O. mykiss SMAV of 11.23 mg TA-N/L used by EPA • value could not be substantiated

7. Final Acute Value (FAV) for the Warm Water database • Four most sensitive genera • Fusconaia (1.3 mg TA-N/L) • Lasmigona (2.8 mg TA-N/L) • Medionidus (4.5 mg TA-N/L) • Pyganodon (4.7 mg TA-N/L) • FAV = 2.8 mg TA-N/L • All Unionidae clams (mussels)

8. Might Need to Reevaluate Revised Warm Water Database…. • In fact, the eight most sensitive species in the revised warm water database are Unionid clams • Considerable uncertainty regarding Unionidae presence or distribution within the State of Colorado • Considerable uncertainty regarding Unionidae ammonia toxicity data • So, split the warm water database into with and without Unionidae • Both still meet eight family rule

9. Warm Water without Unionidae • Four most sensitive genera • Ceriodaphnia (14.2 mg TA-N/L) • Notemigomus (14.7 mg TA-N/L) • Gambusia (15.3 mg TA-N/L) • Etheostoma (18.1 mg TA-N/L) • FAV = 14.8 mg TA-N/L

10. Comparison of EPA Acute vs. Revised • Acute Equations Salmonids present: EPA Acute Equations Salmonids absent Revised Acute Equations Cold-water: Warm-water without Unionidae :

11. Graphic comparison of EPA Acute vs. Revised Acute

12. Evaluation of EPA Chronic Database • Limited chronic database • We also updated chronic database • Lit review and data quality • Removed some data points – added others • No net change in size of chronic database • EPA compelled to use one or two studies to derived CCC model • EPA decided to include a seasonality component to protect presumed sensitive life stages of fish

13. Questions regarding EPA formulation of CCC • Chronic database does not meet 8 family rule! • For “seasonality”, incorporated the temperature “slope” from an acuteammonia toxicity study • Same study used to show temperature not important • Used Hyalella (amphipod) response slope for temperature relationship to represent with and without early life stage fish • And the Hyalella data questionable due to poor control organism performance • Built final equations using early life stage Lepomis and the Hyalella data

14. Alternate chronic approach • Drop temperature component • i.e., drop with and without early life stage approach since no data to support • Either temperature effect or life-stage effect • Revert to more common chronic criteria approach – acute-to-chronic ratios • Updated data provide ACR = 4.7 • Apply to either EPA “with and without salmonid” equations or our “cold, warm, warm w/o unionid” equations

15. Comparison of EPA and CECCCC • Comparison of EPA Chronic and ACR chronic • Similar at higher pH values • EPA values generally less restrictive in cold water • Diverge at mid-to-low pH • especially in warm water 10 SM ACR = 4.5 GM ACR = 4.7 8 6 TA-N (mgN/L) 4 2 0 6.5 7.0 7.5 8.0 8.5 9.0 pH CCC Fish ELS Present @ 24.6°C CCC Fish ELS Absent @ 24.6°C CCC Fish ELS Present @ 9°C CCC Fish ELS Absent @ 9°C CEC-CCC cold water CEC-CCC warm water CEC-CCC warm water w/o Unionids

16. Acute Chronic

17. So, what’s next?! • Keep existing EPA numbers? • Modify acute? • Rather than “with and without salmonids”, use “cold and warm with and w/o unionids”? • Keep EPA chronic? • Modify Chronic using acute-to-chronic ratio approach? • Rather than “with and without early life stages”, use ACR adjusted acute equations