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“The Guidebook applied a science-based understanding, developed the water balance methodology to establish performance targets, and demonstrated that urban watershed restoration could be accomplished over a 50-year timeframe as and when communities redevelop,” states Peter Law, Guidebook Chair (2000 – 2002). A decade ago, looking at rainfall differently led the Province of BC to develop the Water Balance Methodology, and initiate a paradigm-shift in the way rainwater is managed. BC was the first provincial or state government in North America to implement the Water Balance Methodology.

Written for both expert and non-expert audiences, the document explains how the Guidebook provides a transition into ‘Beyond the Guidebook: The New Business As Usual’. “We are using the slogan The New Business As Usual to convey the message that, for change to really occur, practices that until now have been viewed as the exception must become the norm moving forward. We have to build regulatory models and develop models of practice and expertise,” stated Dale Wall, Deputy Minister

Published in March 2002 by the Greater Vancouver Regional District, the “Watershed / Landscape-Based Approach to Community Planning” was developed by an interdisciplinary working group. “At the heart of the approach is an adaptable 10-step methodology that facilitates planning with reference to watershed-based features,” reports Erik Karlsen, a primary author of the document. ‘Stormwater Planning: A Guidebook for British Columbia’ is a prime application of the watershed / landscape-based approach. In the Guidebook context, what happens at the scale of the individual parcel and street affects what happens at the watershed scale.

“Our focus was on the technical details of practices in landscape areas that treat rainwater through plant materials and soils by infiltration, retention, detention and evapotranspiration”, states Ed von Euw. “The objective of this project was to reduce information barriers that previously stood in the way of effective implementation of rainwater source controls.”

When it was released, the Guidebook was a catalyst for action to implement a ‘design with nature’ approach to rainwater management and green infrastructure. “The premise underpinning the Guidebook was that land development and watershed protection can be compatible. The basis for this premise was that municipalities exert control over runoff volume through their land development and infrastructure policies, practices and actions,” states Peter Law. “The Guidebook applied a science-based understanding to develop the water balance methodology and establish performance targets.”

The ISMP Template provides a standardized process that includes all of the key components for rainwater and stormwater management. These are categorized in terms of three disciplines – engineering, planning and environmental. “A municipality can decide which components are applicable, and can establish the level of effort required based on risk and local conditions. Not all of the components may be relevant for a given watershed or drainage catchment,” states Robert Hicks.

Founded on British Columbia case study experience, the Guidebook formalized a science-based understanding to set performance targets for reducing rainwater runoff volumes and rates. These targets represent the synthesis of biological and hydrological understanding. Structured to meet the information needs of different audiences, the Guidebook formalized the ‘Integrated Strategy for Managing the Complete Spectrum of Rainfall Events’,