1. Focus Group Meeting: July 17, 2013 Truckee River Water Quality Standards Review

2. Overview of Topics for Discussion Recap on Water Quality Models to Support WQS Review – Recent updates – Model confirmation report Overview of general approach for WQS modeling Technical decision points Anticipated schedule and milestones 2

3. Recap on Water Quality Models to Support WQS Review

4. Intended Use of Models Explore river water quality response to ranges of point and nonpoint concentrations/loads under range of flow conditions Model results support review of WQS and TMDL – WQS: establish site-specific response to nutrient concentrations – TMDL: help understand possible balances of point and nonpoint loads which result in DO WQS attainment 4

5. Model Linkage for Truckee River WQS Analysis WARMF TRHSPF TROM Reservoir Releases, Diversions DiversionsTributary Flows, Nonpoint Sources In-stream Water Quality Demands, Water Operations, In-stream Flow Targets Meteorology, Land Use, TMWRF Effluent and Re-use TMWRF Effluent

6. WARMF: Watershed Model 125 catchments (subwatersheds) Time step = 1 day 6 Peer reviewed, public domain Predicts watershed flow and pollutant loads based on – land use – meteorological conditions – water management – watershed improvements

7. TRHSPF: River Water Quality Model Based on DSSAMt science (used for 1994 TMDL) Open code, EPA-supported, peer reviewed Calibrated and verified, technology transferred Inputs are flow, watershed loads, point sources Predicts: – water quality response of river – nutrients  periphyton  dissolved oxygen 7

8. Recap of 2011 Model Extension/Update Updated both WARMF and TRHSPF – Extended databases through 12/31/2008 – Models reflect rapid regional growth through 2006 – Refined calibration Model limitations identified in 2011 – Under-prediction of snow melt peaks in wetter years (WARMF) – Under-prediction of flow in Steamboat Creek and North Truckee Drain during summer due to landscape irrigation with potable/reclaimed water (WARMF) – Under-prediction of stream temperature during spring (WARMF) Non-critical periods for dissolved oxygen – Under-prediction of total nitrogen and total phosphorus Non-bioavailable organic nutrient component is low 8

9. Recap of 2011 Model Extension/Update (continued) Overall Model Performance – Results consistent with original calibration – Model performance still acceptable for more recent time periods – Both models considered ready for use to support the third-party WQS and TMDL review efforts Reporting – Documented results in Model Confirmation Report (11/28/11) – Presented results to stakeholders in December 2011 9

10. 2012/2013 Model Extension/Update Goal: keep models current and build confidence in models Extended all databases through 12/31/2011 – Climate, diversions, point sources, air quality, reservoir operations, observed flow, observed water quality – QA/QC of diversion input data to ensure consistency between the watershed and river model Upgraded to WARMF Version 6.5b (released 5/2012) Minor refinement of calibration WARMF: Minor soil coefficient and temperature lapse factor adjustments to improve simulation of extreme low-flow conditions and upper watershed snowmelt hydrology TRHSPF: Slight decrease in rate of organic labile N and P settling 10

11. Snapshot Summary of Results Several previous shortcomings addressed – Improved snowmelt and low flow hydrology in upper watershed – Reduced general under-prediction of total nitrogen – Updated and QA/QC’d diversion data across all models Overall Model Performance – Results “as good as” or “better” for 2000-2008 as compared to prior model update – Results within the range of uncertainty for new years (2009-2011) - 2009 was a challenging/unusual year – Overall, total nutrients are still slightly low Inorganic nutrients within range of uncertainty Organic nutrients slightly low Increasing organic nutrients will not change DO significantly Documented results in updated model confirmation report 11

12. WARMF: Flow at Reno/Sparks 12 Location Modeled Mean Observed Mean Number of Observed Points r2r2 Relative Error Reno/Sparks496.2498.84,3830.89-2.61

13. 13 WARMF: Total Nitrogen at Reno/Sparks Location Modeled Mean Observed Mean Number of Observed Points Relative Error Reno/Sparks 0.350.42145-0.07 North Truckee Drain 1.441.657145-0.17 Steamboat Creek 1.561.63145-0.11 2009 unusual year

14. WARMF: Nitrogen Species at Reno/Sparks 14

15. WARMF: Total Phosphorus at Reno/Sparks 15 Location Modeled Mean Observed Mean Number of Observed Points Relative Error Reno/Sparks0.03 1450.00 North Truckee Drain0.230.221720.00 Steamboat Creek0.280.261710.01

16. WARMF Model Confirmation Summary Flow – Extreme low-flow periods and snow melt peaks improved with minor parameter modifications in upper watershed (above Farad) – r 2 for the Truckee River at Reno/Sparks improved slightly to 0.89 (considered “very good”) Nitrogen – Inorganic nitrogen within range of uncertainty – Total nitrogen generally lower than observed Bias in observed data due to non-detects? Missing or underestimated organic nitrogen source? Phosphorus – Annual and long-term total phosphorus and orthophosphate within range of uncertainty – Many observed TP values at Reno/Sparks below PQL 16

17. TRHSPF: Streamflow at Vista 17 Locationr2r2 N Vista 0.884,383 Near Tracy 0.894,383 Below Derby Dam 0.904,383 Wadsworth 0.884,383 Near Nixon0.864,383 Slight improvement in r 2 from previous model confirmation results

18. TRHSPF: Total Nitrogen at Lockwood 18 2009 unusual year

19. TRHSPF: Total Phosphorus at Lockwood 19 data anomalies?

20. TRHSPF: Dissolved Oxygen (Tracy/Clark: 2002-2005) 20

21. TRHSPF: Dissolved Oxygen (Tracy/Clark: 2006-2011) 21

22. TRHSPF Model Confirmation Summary Flow – r 2 ranges between 0.86 to 0.90 for all stations – Rating of “very good” Nutrients – Model predictions fall within range of uncertainty of observed data for large majority of years (exception is 2009) – Slight under-prediction of TN and TP – Inorganic nutrients are reasonable overall Inorganic N within the range of uncertainty Ortho-P slightly over-predicted – Organic nutrients slightly low Dissolved Oxygen – Model predictions are within the range of the data – Overall model performance is “good” 22

23. Review of Model Confirmation Report Confirmation Report available on TRIG July 23, 2013 – Email to Focus Group – Form for written comments on confirmation report (electronic submittal) – Due August 16 th, 2013 Supplementary background material on TRIG – Original calibration reports – Presentations from previous Focus Group meetings TRIG – Truckee River Info Gateway: – http://truckeeriverinfo.org http://truckeeriverinfo.org 23

24. Overview of General Approach for WQS Modeling Development of Technical Rationale

25. Modeling Approach to Support WQS Review Objective: Identify appropriate site-specific nutrient WQS that when met, would adequately meet DO criteria given a representative flow condition 1.Identify flow condition(s) 2.Test range of instream concentrations of nitrogen and phosphorus 3.Evaluate the extent to which the DO water quality standard will still be met 25

26. Conceptual Plot of Model Results Possible Nutrient WQS % of time DO WQS is violated (Based on representative flow condition) Relationship between Nutrient Concentrations and DO WQS Attainment ? 26

27. Conceptual Plot of Model Results Possible Nutrient WQS 0.040.060.05 % of time DO WQS is violated 0.0 5.0 10.0 Based on representative flow condition ? 27

28. General Approach: Iterative TRHSPF WQS Simulations Representative flow year (TROM output) Linked WARMF – TRHSPF simulation – WARMF provides “baseline” loads and flows into river – TRHSPF run iteratively with different concentrations of TN/TP/Ortho-P Adjust N and P loads into river (increase or decrease) to match annual average river concentrations to “proposed” WQS Locations with adjustments: – East McCarran (upstream model boundary) – Segments with incoming loads (North Truckee Dr., Steamboat Cr., TMWRF) Evaluate resulting attainment of DO WQS 28

29. Matrix of Scenarios Tested with 10 th Percentile and 50 th Percentile Flow Regimes Total Phosphorus and Ortho-P (mg/L) 0.0400.0500.075 0.10 (≈ baseline) Total Nitrogen (mg/L) 0.65 x x 0.75 (≈ baseline) xxxx 0.85 x x 1.00 x x Concentrations vary temporally but hit target WQS on an annual average basis Incoming loads are adjusted at upstream boundary (E. McCarran), North Truckee Drain, and Steamboat to hit target WQS 29

30. Technical Decision Points

31. Technical Decision Points for Focus Group Input WQ models: Review Model Confirmation Report and confirm that model calibration is complete and satisfactory (Jul) WQS modeling process – General approach for analysis (Jul) – Selection flow years/conditions for analysis (Aug) – Analysis of model results (spatial aggregations, critical reach, critical season/month) (Aug) – Speciation of Phosphorus WQS: Ortho-P vs. TP (Aug/Sep) – TN WQS: evaluation of both single value max and annual ave. WQS (Aug/Sep) Results of WQS model runs (Aug/Oct) Technical Rationale for WQS revision (Oct/Jan) 31

32. Anticipated Schedule and Key Milestones

33. Next Steps Focus Group comments and feedback: – Model Confirmation Report – Technical approach Working group proceeding with resolution of technical decision points Continuation of preliminary WQS model runs Upcoming Focus Group Workshops (City of Fernley) – Aug 28, 2013 (W): 9 AM – 12 PM Comments on model confirmation report due August 16 – Sep 18, 2013 (W): 9 AM – 12 PM – Oct 16, 2013 (W): 9 AM – 12 PM – Jan 15, 2014 (W): 9 AM – 12 PM – Additional Stakeholder / Focus Group meetings TBD in 2014 33

34. NDEP Timeline 12/1/2013: Preliminary Draft LimnoTech report on modeling 1/1/2014: Review completed by Working Group 1/15/2014: Draft LimnoTech report on modeling results 2/15/2014: Review completed by Focus Group 3/1/2014: Final LimnoTech report on modeling results 4/1/2014: Draft NDEP Rationale/Petition for proposed standards changes 5/1/2014: NDEP Workshops – Focus Group, general public 6/30/2014: Final NDEP Rationale/Petition to LCB 34