Hydrologic Indices Yuba River Development Project FERC Project 2246 Relicensing Thursday, April 11, 2013 Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Hydrologic Indices Introduction Hydrologic index usage Existing indices in the Yuba River watershed Unimpaired Yuba River flow at Smartsville Comparison of indices Comparison of indices and Middle Yuba River flow Comparison of year-type classifications Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Yuba River Watershed Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Hydrologic Index Usage Hydrologic Indices have two purposes: Characterize hydrology Define year-type classifications Characterizing hydrology is critical to ensure accurate representation of a natural process Year-type classifications are a statistical exercise to make sure bins capture correct flow ranges Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Existing Indices in Yuba River Watershed Existing YCWA FERC License (4 WY) Based on annual unimpaired flow at Smartsville Year-types defined by percentage of 50-year average unimpaired flow Yuba River Index (5 WY) Part of RD-1644, no current application for determining flows Based on weighted unimpaired flow at Smartsville 0.2*(prev index) + 0.3*(Oct-Mar) + 0.5*(Apr-Jul) North Yuba Index (6 WY) Part of Yuba River Accord Based on end-of-Sept. New Bullards Bar storage + annual inflow YB/DS Index (6 WY) Part of proposed license conditions Based on annual unimpaired flow at Smartsville Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Annual Unimpaired Yuba River Flow at Smartsville Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Annual Unimpaired Yuba River Flow at Smartsville Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Selected Comparisons of Existing Indices Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Selected Comparisons of Existing Indices Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Comparisons of Existing Indices Three primary indices generally characterize hydrology similarly. Slight differences due to variations in approach YRI emphasizes April-July runoff, so years like WY 2013 are represented as drier than in YB/DS NYI includes storage, so transitions from dry to wet are represented as drier than in YB/DS (and inverse) Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Existing Indices vs. Middle Yuba River Flow Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Existing Indices vs. Middle Yuba River Flow Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Existing Indices vs. Middle Yuba River Flow Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Existing Indices vs. Middle Yuba River Flow Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Existing Indices vs Middle Yuba River Flow Existing indices do a good job of representing annual hydrology of the Middle Yuba River Monthly variability in Middle Yuba River flow is not well represented Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Comparison of Year-Type Classifications Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Comparison of Year-Type Classifications Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Comparison of Year-Type Classifications Index Schedule 1/ Wet Schedule 2/ Above Normal Schedule 3/ Below Normal Schedule 4/ Dry Schedule 5/ Critical Schedule 6 (7)/ Extremely Critical (Conference) North Yuba Index (1) Yuba River Index YB/DS Index Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Comparison of Year-Type Classifications Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Year-Type Distribution Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Year-Type Distribution Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Year-Type Distribution Yuba River Development Project (YRDP) FERC Project 2246 Relicensing Where do we go from here?