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

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 EPA Acute Equations Salmonids present: 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 acute ammonia 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 CEC CCC 0 2 4 6 8 10 6.57.07.58.08.59.0 pH TA-N (mgN/L) 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 SM ACR = 4.5 GM ACR = 4.7 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

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