Stormwater Manual
hose gushing water onto permeable paversTraditional stormwater management strategies focused on conveyance and detention. Storm sewers were designed to move stormwater off urban landscapes to detention basins to reduce downstream flooding. The Iowa Stormwater Management Manual provides new stormwater management strategies that compliment the conveyance and flood control efforts of the past. The manual provides information on hydrologic changes with urban development, uniform sizing criteria, low impact development alternatives and design guideline for practices that protect water quality and reduce stream corridor erosion.

Historically, 90 percent of annual rainfall has been from events that are less the 1.25 inches. A primary focus of the manual is to provide design guidelines for practices that infiltrate small runoff events to protect water quality. The manual also provides design guidelines for stream corridor protection, which is important because stream corridor erosion causes up to 70 percent of sediment loading in urban areas. These practices provide significant water quality benefits, and protect pipelines, sanitary sewers and other infrastructure. Adding water quality and channel protection practices to traditional conveyance and flood control practices will make our stormwater management strategies more holistic and effective.

Stormwater Manual

Due to file size, various sections have been broken out and are available for individual download:
   Chapter 1 - Specifications
   Part 2A - General Information
   Part 2B - Unified Sizing Criteria
    Part 2C - Storm Water Hydrology
   Part 2D - BMP Types and Applications
   Part 2E - Infiltration Practices
   Part 2F - Filtration Practices
   Part 2G - Detention Practices
   Part 2H - Storm Water Wetlands
   Part 2I - Vegetated Swale Systems
   Part 2J - Pavement Systems
   Part 2K - Mechanical Systems
    Part 2L - Coagulation and Flocculation
    Part 2M - Storm Sewer Design
    Part 2N - Design of Culverts
    Part 2O - Open Channel Flow
    Part 2P - Storm Water Easements
    Part 2Q - References
    Part 2R - Green Roof Systems