Reports - Engineering
2022 State of the Basin Report

West Yost, Watermaster's engineering consultant, produces the State of the Basin Report every two years reporting on the current health of the Basin and the status of Optimum Basin Management Program. For the latest report, click the button immediately below. See gray section below for a complete listing of published reports.

2022 State of the Basin Report


OBMP Staff Status Report 2023-1

Every six months, Watermaster produces the OBMP Semi-Annual Status Report. This twice a year report summarizes the progress of the OBMP implementation during the previous six months. For the latest report, click the button immediately below. See gray section below for a complete listing of published reports.

OBMP Staff Status Report 2023-1


1D Model Simulation of Subsidence in Northwest MZ-1 - Subsidence Management Alternative No. 1

Formerly known as the Land Subsidence Committee, the Ground-Level Monitoring Committee produce a report annually summarizing the activity that occurred throughout the preceeding year. For the latest report from this committee, click the button immediately below. See gray section below for a complete listing of published reports.

1D Model Simulation of Subsidence in Northwest MZ-1 - Subsidence Management Alternative No. 1


Annual Report of the Prado Basin Habitat Sustainability Committee, Water Year 2022

The Prado Basin is a flood control area in the southern portion of the Chino Basin. Since the construction of the Prado Dam in 1941, a riparian habitat had developed in this region including species with protected statuses. The Prado Basin Habitat Sustainability Committee was formed to help protect the riparian habitat. For the latest report from this committee, click the button below. See gray section below for a complete listing of published reports.

Annual Report of the Prado Basin Habitat Sustainability Committee, Water Year 2022


Routinely Published Reports
OBMP State of the Basin Reports
Available Reports
OBMP Semi-Annual Status Reports
Available Reports
Ground Level Monitoring Committee
Available Reports and Related Documents
Prado Basin Habitat Sustainability Committee
Available Reports and Related Documents
Maximum Benefit/Hydraulic Control
Available Reports and Related Documents
Streamflow Monitoring Reports
Available Reports

Other Reports and Documents

Watermaster has periodically recalculated the Safe Yield of the Chino Basin using its groundwater-flow model. The linked documents include the past Safe Yield recalculations (2015 and 2020) and the current methodology to recalculate the Safe Yield, which was updated in 2022. Materials related to the current 2025 Safe Yield Reevaluation effort can be found here.

The linked reports document Watermaster's use of its groundwater-flow model for investigations beyong Safe Yield recalculations, including the evaluation of the Peace II Project Description (2007), the biennial model update and required demonstrations, and evaluations of potential Storage and Recovery Programs.

The 2000 Optimum Basin Management Program (OBMP) and the subsequent 2020 OBMP Update is the guiding groundwater management program for the Chino Basin. The OBMP describes the management goals for the basin and the necessay actions to achieve the goals. Information and materials on the collaborative stakeholder process that supported the development of the 2020 OBMP Update can be found here.

Watermaster develops and updates a Recharge Master Plan to organize, enhance, and improve recharge to the Chino Basin pursuant to Watermaster policies and the management goals defined in the OBMP. Recharge Master Plans are updated at least every five years, with the most recent update occurring in 2023.

Monthly recharge activities based on IEUA's reporting of Groundwater Recharge may be found here.