Version "DSM2 Input 2025-09-18 historical update" is based on version "DSM2 Input 2025-07-03 historical update", and includes the following changes:

To improve representation of the west to east preferential flow path through Franks Tract:

• Reservoir connection coefficients for the node 103 connection are changed from 2250 to 3000,
• Reservoir connection coefficients for the node 225 connection are changed from 1500 to 4000.
• A new connection to Old River (node 102) added to Franks Tract.

Changed NDUPLICATE values and flow coefficients (CF_FROM_NODE, CF_TO_NODE) for pipes representing South Delta temporary barrier leakage and culvert flow. These changes improved water levels and salinity representation, as well as making the values consistant with the SCHISM calibration.

Reduced Manning's n in Montezuma Slough to improve tidal flow results at station NSL.

Version 2025-09-18 uses the same model grid and calibration as version 2025-05-28, which was calibrated using DSM2 v8.4.1. However, we recommend using DSM2 v8.4.2, which includes a bug fix to allow the variable "NDUPLICATE" for GATE_WEIR_DEVICE to vary in time. This provides a more accurate representation of Clifton Court Forebay gate operations by allowing the number of gates open to be specified as a time series.

Drainage EC time series input are the same used in the last two releases "DSM2 Input 2025-05-28 historical update" and "DSM2 Input 2025-07-03 historical update", consisting of climatology EC values for all years except for 2021-2023, and inferred source EC values for 2021-2023.

All output location files have been updated to the grid used in this version. New files have been added to the common_input folder:

• Files for O&M compliance stations (output_om_compliance_ec.inp and output_om_compliance_stage.inp).
• output_mid_r_flow.inp was created using adjusted coordinates for station MDM, because the station exists in a single channel, but is represented in DSM2 by two channels that are roughly parallel. Output flow locations for station MDM were removed from all other output location files. Users who wish to create a flow output for this location are encouraged to include this file rather than creating another output location, to reduce the risk of error. This file is included by default in the hydro.inp file.
• output_hydro_gates_res.inp: this file contains hydro output locations for gates and reservoirs. This information was previously in the file output_stations_hydro.inp.

Source code and executables: DSM2 HYDRO, QUAL, and PTM: https://github.com/CADWRDeltaModeling/dsm2/releases/

DSM2 input 2025-09-18 release: https://data.cnra.ca.gov/dataset/dsm2-input-2025-09-18-historical-update