1. LC TMDL Modeling Strategy W. Walker Walk Thru July 2011 Progress Report Data Strengths & Weaknesses Preliminary Testing Results Dynamic vs. Steady State Models Sensitivity & Uncertainty Analysis Software Demonstrations – BATHTUB – Load Calculation Ideas for Workplan

2. Tune Up Add TMDL Goal to TP Test Slide Hyperlinks Path Forward - Live

3. Path Forward Task..

4. Model Testing Results

12. Data Limitations 1992-2010 vs 1990-1991 Lower Sampling Frequency: weekly/biweekly -  monthly + high flow Less Winter Sampling No Minor Tributaries Tributary data limited in lake segments the deviate most from model predictions – Mississquoi Bay (missing Rock 1992-2006) – St Albans Bay (no inflow data 1992-2007) – South Lake (~46% of inflows gauged) Complexifying model will not improve forecasts if the inflows are not accurately specified General Ranking – 1990-1991: high – 1992-1999: low – 2001-2008: OK – 2009-2010: high

13. Precision of Measured TP Loads & Lake Concentrations

18. Number of TP Samples vs. Tributary & Water Year

19. Precision of Yearly TP Load Estimates Relative Standard Error = Std Error / Mean

24. Variability & Uncertainty

27. Model Categories Steady Steady-State Dynamic “Quasi-Dynamic”