Western Washington Hydrology Model (WWHM)

This dataset includes versions of the WWHM as they are released, including installation files and descriptions of changes along with dates and version numbers.

WWHM2012 is still the official program to be used by permittees for compliance with MS4 Permits. WWHM2025 is a test/Beta version.

Data and Resources

Additional Info

Field Value
Source https://data.wa.gov/resource/5sqj-8rp7
Author Washington State Department of Ecology Open Data
Last Updated May 14, 2026, 02:20 (UTC)
Created July 22, 2025, 20:37 (UTC)
1. Water Quality Program
2. Data Disclaimer - https://ecology.wa.gov/About-us/Accountability-transparency/Website-information/Copyright-information
Category Natural Resources & Environment
Originator Washington State Department of Ecology
Period of Time 2012-2021
Posting Frequency Annually
harvest_object_id b91bb101-fc02-4ef0-a37f-7f97940af637
harvest_source_id c4128faf-39ff-4aa3-918e-8a395702cab3
harvest_source_title washington-state