The Colorado Floodplain and Stormwater Criteria Manual (Statewide Manual) contains information and guidelines for floodplain and stormwater management practices.
The CWCB designates and approves the state's floodplains under the provisions of its Rules and Regulations for Regulatory Floodplains in Colorado. The criteria outlined in this Manual are technical guidelines for those Rules and Regulations for Regulatory Floodplains. The criteria outlined in this Manual may be revised as necessary and adopted and implemented by communities to assist in floodplain management.
In 2021 the CWCB will begin the process of revising the Manual due to recent changes to FEMA’s Guidelines and Standards for Flood Risk Analysis and Mapping Activities.
Manual
Browse the Table of Contents and read the Executive Summary.
Chapter 1 - General Provisions covers the following topics:
Section 1 – Purpose
Section 2 – Applicability to Existing Drainage Manuals
Section 3 – CWCB Authority and Roles
Section 4 – Colorado Flood History
Section 5 – Applicable Drainage Laws
Section 6 – Definition of Terms and Acronyms
Chapter 2 - Principles covers the following topics:
Section 1 – CWCB Rules and Regulations
Section 2 – CWCB Operating Principles
Chapter 3 - Floodplain and Stormwater Management covers the following topics:
Section 1 – Floodplain Management
Section 2 – Stormwater Management
Chapter 4 - Permit Requirements covers the following topics:
Section 1 – Local Permits
Section 2 – State Permits
Section 3 – Federal Permits
Chapter 5 - Report Submittal Requirements covers the following topics:
Section 1 – Revision of Existing Floodplains
Section 2 – Delineation of New Floodplains
Section 3 – Subdivision Drainage Submittals
Chapter 6 - Flood Preparedness Activities and Flood Hazard Mitigation covers the following topics:
- Authority & Responsibility
- Existing Mitigation Plans, Programs & Structures
- Mitigation Strategies
Chapter 7 - Information Resources and Networks covers the following topics:
- Floodplain Resources
- Hydrology Resources
- Hydraulic Resources
Chapter 8 - Mapping Standards and Modernization covers the following topics:
- Federal guidelines and specifications for flood hazard mapping partners
Chapter 9 - Hydrologic Analysis covers the following topics:
Section 1 – Methods and Applications
Section 2 – Statistical Analysis
Section 3 – Regional Regression Analysis
Section 4 – Rainfall
Section 5 – Runoff
Section 6 – Mean Annual Flow Analysis
Chapter 10 - Hydraulic Analysis covers the following topics:
Section 1 – Detailed Method
Section 2 – Limited Detailed Method
Section 3 – Approximate Method
Chapter 11 - Floodplain Delineation covers the following topics:
- Level of Study
- Watershed Development Conditions
- Flood Hazard Zone Designations
- Detailed Floodplain Delineation Method
- Limited Floodplain Delineation Method
Chapter 12 - Unique Hydraulic Conditions covers the following topics:
Section 1 – Alluvial Fan Hazards
Section 2 – Mudflow, Debris Flow
Section 3 – Irrigation and Stormwater Interaction
Section 4 – Ice Jams
Section 5 – Drainageway Buffer Zones and Setback Limits
Section 6 – Two-Dimensional Modeling
Chapter 13 - Hydraulic Analysis and Design covers the following topics:
Section 1 – Open Channels
Section 2 – Bridges and Culverts
Section 3 – Dams and Reservoirs
Section 4 – Levees
Section 5 – Detention Basins
Section 6 – Drop Structures
Section 7 – Recreational Structures
Chapter 14 – Storm Drain Systems covers the following topics:
Section 1 – Storm Drains
Section 2 – Streets
Chapter 15 – Storm Drainage Water Quality covers the following topics:
Section 1 – Stormwater Quality Management Principles
Section 2 – Best Management Practices