1. Model Application for WQS Review Process December 14, 2011 Laura Weintraub

2. Intended Use of Models for WQS Review Provide linkage between nutrient concentrations in the Truckee River and resulting dissolved oxygen levels Account for other factors (flow, temperature, light, organic matter, aeration) Understand balance of nutrient concentrations which result in DO WQS attainment under a range of flow conditions 2 Dissolved Oxygen Sunlight Flow Algae Aeration Nutrients (N&P) Temperature Organic Matter

3. Water Quality Modeling to Support WQS Review Objective: Identify appropriate (site-specific) nutrient WQS that when met, would adequately meet DO criteria given a representative low flow condition 1.Identify low flow condition 2.Test range of instream concentrations of TN, TP, Ortho-P 3.Evaluate the extent to which the DO water quality standard will still be met 3

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

5. Model Linkage – WQS Evaluation Watershed Model Water Quantity Water Quality Model Land Use Climate Soil Types Management Practices Water Quality Nutrient Loads WWTPs WARMFTRHSPF 5 Flow Management Model Baseline Run

6. Model Linkage – WQS Evaluation Water Quantity Water Quality Model Water Quality Nutrient Conc. WWTPs TRHSPF 6 Flow Management Model Iterations over a range of instream nutrient concentrations will not require additional WARMF runs Iterative Scenarios

7. Water Quality Model Linkage 7

8. Model Assumptions Flow management model will provide model inputs reflective of historical hydrology under selected river operations: –Reservoir releases –Diversions –TMWRF discharge flows Climate – consistent with selected representative year Land use / land cover – updated layer circa 2006 Evaluate results for Water Year (not calendar year) 8