Problems with Bay-Delta water resources modeling have been recognized for decades

The drought years of 2021 and 2022 saw major errors in the Department of Water Resources' Bulletin 120 runoff forecasts and Delivery Capability Report water supply projections. The Joint Legislative Audit Committee authorized an audit of DWR's modeling and water management on June 27, 2022. But the model errors are part of larger institutional issues … Continue reading Problems with Bay-Delta water resources modeling have been recognized for decades

Models that forecast water that isn’t there hurt all beneficial uses

Assemblymember Adam Gray has called for an audit of the Department of Water Resources and the State Water Resources Control Board, in part to answer the question, What happened in the Water Year 2021 (October 1, 2020 to September 30, 2021) to lead the state to miscalculate by some 700,000 acre-feet the amount of water … Continue reading Models that forecast water that isn’t there hurt all beneficial uses

Fatal errors in DWR’s runoff forecasting: comments to the State Water Resources Control Board

The State Water Resources Control Board held a workshop today (March 16, 2022) on Sacramento River Temperature Management. Among the topics considered were "hydrologic conditions, including operations, forecasting, and accounting." These were my comments. This is Deirdre Des Jardins with California Water Research. I’m the physicist who sent comments to DWR in 2012 predicting the … Continue reading Fatal errors in DWR’s runoff forecasting: comments to the State Water Resources Control Board

Dear DWR, in runoff forecasting, stationarity is dead

For decades, the California Department of Water Resources (DWR) has relied on runoff forecasts from the California Cooperative Snow Surveys (Bulletin 120) for planning State Water Project operations in the late winter and early spring. In 2021, the Bulletin 120 runoff forecasts, which were based on the last 50 years of historic runoff data, were … Continue reading Dear DWR, in runoff forecasting, stationarity is dead