Improving ditch maintenance for water quality
Roadside ditches can help manage the flow and quality of stormwater and play an important role in clean water. These resources for maintenance and planning can make these simple, common features an important contributor to clean water. The Ditch Maintenance project includes:
- refinement of ditch maintenance standards and enlarging the ditch maintenance toolbox;
- assessment of the characteristics and condition of several of King County's roadside ditches; and
- a literature review on background data.
King County, with members of the Regional Operations and Maintenance Program (ROADMAP) and Herrera Environmental Consultants and used the information from the field evaluation, literature review and input from ROADMAP members to develop a ditch maintenance matrix, field guide, and fact sheets to improve maintenance, operations and design.
- Ditch Maintenance Matrix (208 KB)
- Field Guide to Roadside Ditch Maintenance in Western Washington (4.2 MB)
For field staff performing ditch maintenance:
- Considerations for Field Evaluation of Roadside Ditches (Fact Sheet F1, 4 MB)
- Ditch Cleaning Strategies (Fact Sheet F2, 3.4 MB)
- Maintaining Ditches that Convey Natural Flow (Fact Sheet F3, 2.1 MB)
For administrative or office staff overseeing and providing direction for stormwater operations, maintenance and/or stormwater capital projects:
- Ditch Mapping Recommendations (Fact Sheet A1, 1.5 MB)
- Prioritizing Ditches for Inspection and Maintenance (Fact Sheet A2, 2.5 MB)
- Permit Requirements for Ditch Maintenance (Fact Sheet A3, 2.1 MB)
- Source Control Strategies for Ditches (Fact Sheet A4, 970 KB)
- Ditch Retrofit Strategies (Fact Sheet A5, 3.3 MB)
The project team also prepared a set of GIS and field data collection tools to support a roadside ditch inventory and assessment. These tools include:
- Guide to Roadside Ditch Inventory and Assessment Tools Technical Memorandum (340 KB)
- Geodatabase framework to facilitate desktop GIS evaluation of ditch significance (41 KB ZIP containing GDB)
- Survey123 field form template to facilitate collecting data on ditch condition in the field (54 KB)
- ArcGIS toolbox for processing the desktop ditch significance and field evaluation ditch condition data to produce cumulative scores and assign maintenance priorities (34 KB ZIP containing TBX)
Funding for this project was from a 2019 National Estuary Program grant from Washington State Department of Ecology. For questions about improving ditch maintenance for water quality, please contact Jessica Engel, Water Quality Planner, King County Water and Land Resources Division Water Quality Compliance Unit.