Forest Practices Code, Province of B.C.

Ministry of Forests HomepageGovernment of British Columbia Homepage

This Forest Practices Code Guidebook is presented for information only

It is not cited in regulation. The Forest and Range Practices Act and its regulations took effect on Jan. 31, 2004. This replaced the Forest Practices Code of British Columbia Act and regulations. For further information please see the Forest and Range Practices Act.

This guidebook was superceded by the following 1999 Watershed Assessment Procedure Guidebook available at: /tasb/legsregs/fpc/FPCGUIDE/wap/WAPGdbk-Web.pdf  


Interior Watershed Assessment Procedure Guidebook (IWAP)

Level 1 Analysis

September 1995


Forest Practices Code of British Columbia Act
Operational Planning Regulation
Part 3 (Forest Development Plans)

Table of Contents


Overview of the watershed assessment procedure
When to do a watershed assessment

The interior watershed assessment procedure

The multi-agency round table
Level 1 analysis
Level 2 and 3 analyses
Developing watershed constraints for the forest development plan

Level 1 analysis procedure

Map work
Data compilation
Peak flow
Surface erosion
Riparian buffers
Other land uses
Watershed characteristics
IWAP conversion table
Watershed report card

Interpretations and recommendations

Determining hazard index scores
Level 2 watershed assessment (channel assessment procedure)
Air photograph analysis
Field assessments
Making interpretations and recommendations
Interpretation matrices
Interpretation worksheet


  1. Terrasoft procedure for following the interior watershed assessment procedure
  2. Compilation of data sources needed to complete the IWAP
  3. Identification of stream orders, sub-basins and the point of interest in community watersheds
  4. How to produce a hypsometric curve and determine the H60 elevation.
  5. Definition of unstable slopes and those with a potential for mass wasting
  6. Definition of areas with a potential for surface erosion
  7. Identification of fish-bearing stream reaches and potential stream temperature concerns
  8. Effects of harvesting on stream flow and directions on calculating equivalent clearcut area (ECA)
  9. Forestry impacts on surface erosion and directions on filling in the surface erosion and road inventory forms
  10. Forestry impacts on floodplains and riparian zones and directions on filling in the riparian forms
  11. Forestry impacts on landslides and mass wasting and directions on filling in the mass wasting forms
  12. Hydrological zone map
  13. Classification of bedrock geology
  14. Other land uses that potentially affect water quality
  15. Computer spreadsheet version of the IWAP  (NO LONGER AVAILABLE)



  1. Flowchart showing the watershed assessment procedure.


  1. Interior watershed assessment conversion table


  1. Area measurements by elevation band and sub-basin
  2. Peak flow index calculations by sub-basin
  3. Road inventory and density
  4. Roads adjacent to streams
  5. Riparian buffer impacts
  6. Landslide hazard
  7. Other land uses
  8. Watershed characteristics by sub-basin
  9. Watershed characteristics by sub-basin
  10. Watershed report card
  11. Hazard index


  1. Peak flow vs. channel instability
  2. Peak flow vs. surface erosion
  3. Peak flow vs. mass wasting
  4. Mass wasting vs. channel instability
  5. Riparian vs. channel instability

[Return to top of document]
Please note:
See Disclaimer for information about how to receive an official copy of these publications.