Stormwater Management

Low Impact Development ManualsLow Impact Development (LID) is a site design strategy that seeks to mimic the pre-development site hydrology.  LID techniques include the use of small-scale landscape-based best management practices (BMPs) to treat and infiltrate stormwater runoff.  LID also requires the preservation and protection of environmentally sensitive features such as riparian buffers, wetlands, steep slopes, valuable trees, flood plains, woodlands, native vegetation, and permeable soils.

Under direction from the regional water board, the North Coast Stormwater Coalition has updated the LID manual. These changes accommodate changing ASTM (American Society for testing and materials) standards and requirements from the state. Under the new guidelines put in place, Infiltration Trenches/Basins are no longer applicable as LID installations. Furthermore, details have been added to the manual concerning hydromodification and testing protocols. The LID manual link below has been updated to the most recent version and reflects these changes.

More information on these requirements is provided below.

12th St integrated stormwater project

The stormwater integration project along 12th Street in Fortuna intends to incorporate various stormwater techniques to mitigate local flooding and trash accumulation that occurs as a result of large impervious areas incapable of properly managing stormwater. The site currently conveys stormwater through street curbs, gutters, and underdrains which directs runoff into the storm drainage system prior to untreated discharge into Rohner Creek. The stormwater features will provide additional methods of storing, treating, infiltrating, and conveying the runoff. Additional improvements to the storm drainage system will provide further runoff management capacity for the site which includes sidewalk underdrains, stormwater drain inlets, and storm drain piping. See the links below for the project brochure and interpretive sign that have been created for the project:

The project was completed in the fall of 2023, and has already served to improve stormwater conveyance and trash capture along 12th Street. Although this project represents a significant milestone in the improvement of drainage conditions in the City’s downtown neighborhoods, the City recognizes the need for continued improvements to be made in order to reduce the overall amount of stormwater under surface flow conditions in the area. In the coming years staff will continue to work to identify solutions and projects that will further reduce the amount of surface flow, which will help with localized flooding in the downtown area.

2005 Storm Drain Master PlanFollow these links to download the City of Fortuna’s 2005 Storm Drainage Master Plan (Winzler & Kelly). The plan includes a combined hydrologic/hydraulic modeling analysis of the City’s stormwater infrastructure and presents Citywide system capacities and deficiencies. The plan’s design basis is the 25-year storm event, which is consistent with City’s current stormwater design standard. The results presented in this plan can be used for assessing the impacts of new development on the existing stormdrain system. Contact the City Engineering Department with any questions on the plan.