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?