The watershed data management (WDM) database SC20.WDM is updated with the processed data for the period October 1, 2019, through September 30, 2020. The precipitation data are collected from a tipping-bucket rain-gage network and the hydrologic data (stage and discharge) are collected at USGS streamflow-gaging stations in and around DuPage County, Illinois. Hourly precipitation and hydrologic data for the period October 1, 2019, through September 30, 2020, are processed following the guidelines described in Bera (2014) and Murphy and Ishii (2006) and appended to SC19.WDM and renamed as SC20.WDM. Meteorological data (wind speed, solar radiation, air temperature, dewpoint temperature, and potential evapotranspiration) from October 1, 2019, through September 30, 2020, are copied from ARGN20.WDM and appended to SC20.WDM. Data in dataset number (DSN) 107 and 801–810 are used in comparisons of precipitation data. DSN 107 contains hourly precipitation data collected at Argonne National Laboratory at Argonne, Illinois. DSN 801-810 contains the processed Next Generation Weather Radar (NEXRAD)-multisensor precipitation estimates (MPE) data from 10 NEXRAD–MPE subbasins in the Salt Creek watershed as described in Bera and Ortel (2018). Data in these DSNs are not quality-assured and quality-controlled. The data are downloaded and uploaded daily into a WDM database that is used for the real-time streamflow simulation system. Data from DSN 107 and 801-810 are copied from this WDM and stored in SC20.WDM. DSN 107 and 801-810 are updated with the data through September 30, 2020. Data in DSN 5400 (water-surface elevation at the quarry) and 5700 (water surface elevation at Thorndale) are updated through September 30, 2020, similarly (Murphy and Ishii, 2006). Errors have been found in each of ARGNXX.WDM prior to Water Year (WY) 2023. XX represents last two digits of a WY. A WY is the 12-month period, October 1 through September 30, in which it ends. SC20.wdm contains erroneous meteorological data and related flag values thereby. SC20.WDM is removed. User is advised to download SC22.WDM from https://doi.org/10.5066/P14D6FRA. SC22.WDM (Bera, 2024b) contains corrected meteorological data from ARGN23.WDM (Bera, 2024a) for the period from January 1, 1997, through September 30, 2022. This database file also contains the quality-assured and quality-controlled hydrologic data for the period January 1, 1997, through September 30, 2022, processed following the guidelines documented in Bera (2014). While SC20.WDM is available from the author, all the records in SC20.WDM can be found in SC22.WDM as well. Table1.csv contains the complete list of missing precipitation data periods and the nearby stations used to fill in those missing periods during October 1, 2019, through September 30, 2020. The list of snow affected days of precipitation data and the missing and estimated period of the stage and flow data in SC22.WDM database during the period October 1, 2019, through September 30, 2020, are given in the USGS annual Water Data Report at https://waterdata.usgs.gov/nwis. To open the WDM database SC22.WDM user needs to install Sara Timeseries utility described in the section "Related External Resources". First posted - March 21, 2022 (available from author) References Cited: Bera, M., 2024a, Meteorological Database, Argonne National Laboratory, Illinois: U.S. Geological Survey data release, https://doi.org/10.5066/P146RBHK. ____ 2024b, Watershed Data Management (WDM) Database (SC22.WDM) for Salt Creek Streamflow Simulation, DuPage County, Illinois, January 1, 1997, through September 30, 2022: U.S. Geological Survey, https://doi.org/10.5066/P14D6FRA. Bera, M., and Ortel, T.W., 2018, Processing of next generation weather radar-multisensor precipitation estimates and quantitative precipitation forecast data for the DuPage County streamflow simulation system: U.S. Geological Survey Open-File Report 2017–1159, 16 p., https://doi.org/10.3133/ofr20171159. Bera, M., 2014, Watershed Data Management (WDM) database for Salt Creek streamflow simulation, DuPage County, Illinois, water years 2005–11: U.S. Geological Survey Data Series 870, 18 p., http://dx.doi.org/10.3133/ds870. Murphy, E.A., and Ishii, A.L., 2006, Watershed Data Management (WDM) database for Salt Creek streamflow simulation, DuPage County, Illinois: U.S. Geological Survey Open-File Report 2006–1248, 34 p. Sara Timeseries utility at https://www.respec.com/product/modeling-optimization/sara-timeseries-utility/.