Metropolitan’s SWP Supply Forecasting and Optimal Scheduling CWEMF Annual Meeting February 27, 2007 Peter Louie Metropolitan Water District of So. California

Objectives Improve short-term water management decision-making and scheduling for MWD Allow varying levels of risk to be considered in decision-making Utilize optimization to mimic water supply, water quality, and cost preferences

MWD Water Operations Regional water supply to 6 counties n 26 Member Agencies n Supply 18 million people n Supply 1.5 billion gallons of water/day n 1,072 miles of pipelines, tunnels, & canals n 5 treatment plants n 17 reservoirs n 16 hydroelectric power plants n 45 major control structures n 5 pumping plants on the CRA  SWP entitlement: 1.9 MAF (2006)  CRA entitlement: 652 TAF

Dry-Year Portfolio San Joaquin Valley transfers Sacramento Valley transfers & DWR Drought Bank Surface Reservoirs Surface Reservoirs Multi-Year Programs Multi-Year Programs (Ground water) (Ground water) Single-Year Options Single-Year Options (Transfers) (Transfers) Lake Perris Skinner Reservoir Diamond Valley Lake Lake Mathews Castaic Lake San Luis Reservoir Kern Delta W.D. Semitropic W.S.D. Hayfield Basin Coachella Valley W.D. Imperial I.D. Palo Verde I.D. Arizona Banking Arvin-Edison W.S.D. San Bernardino Valley M.W.D. Mojave W.A.

DecJanMayFebMarAprNovDec EWA Negotiations SWP initial Allocation SBVMWD Transfers Notification Kern Delta Notification For Put only Decision to take SBVMWD Transfers Final Kern Delta Notification Put/Take Arvin Edison Notification Put/Take Turnback Pool B Semitropic Notification Put DWCV Callback Notification Semitropic Notification Take SWP Final Allocaton DWCV Deliveries Set Carryover Limits WSDM Action Timeline

SWP Forecasts WQ, WS Delta Ops Aqd./Res. Model Transfers North of Delta Transfers South of Delta CRA Forecasts WQ, WS MWD Dist. System Model Availability of quantity, timing and wq characteristics Availability of quantity, timing and wq characteristics Allocation and storage conditions wq characteristics Allocation and storage conditions wq characteristics Res. ops/ wq targets for treatment plants/ consumptive use/seasonal storage WQCP/ESA/EWA/b2 and other Delta regulations and requirements Tracking wq System Models Integration And Optimization Schema Optimization Procedure LP/DP approach to determine the desirable combination of SWP/CRA/ EWA/Transfers/MWD storage ops in meeting both the ws/wq objectives.

Overall Analytical Approach

SWP Allocation Forecasting Tool Source Data CAM Input Runtime Control/ Data Setup

Period of greatest uncertainty: October – January Critical information –Risk of spill of carryover storage –Initial allocation –Positional Analysis provides broad sampling of possible hydrologic conditions –Monte-Carlo simulation with uniform sampling of historic hydrology Climate indicators may indicate skewness from the uniform sampling –Reshaping of Position Analysis inputs –As forecast becomes available, CAM stand-alone may be used in conjunction with PA-CAM Projections under Poor/No Forecast

Improving forecasts: February – May Critical information –Delivery reliability –Storage conditions P25, P50, P75, P90, P99 forecasts provide traces of possible hydrologic conditions CAM stand-alone study provides delivery and storage estimates Longer term assessed with CAM-PA simulations Projections with Available Forecast

SWP Allocation Forecasting Tool Source Data CAM Input Runtime Control/ Data Setup

Precipitation Indices Precipitation or Climate Indices Official B-120 Forecast Historical Inflow Traces Ranked Inflow Distribution + + = = Updated Inflow Distribution Method for developing revised inflow distributions

Proposed Monte Carlo simulation method

Summary Forecast-Optimization approach shows promise for improving MWD water management Consideration of uncertainty allows MWD decision-makers/operators to assess internal risk Optimization approaches are actively being used in SWP and MWD systems Future work will consider continuously-updated adjustments to forecasts Prototype for MWD’s SWP-side supplies may be expanded