Rainwater Management in a Watershed Context: Tools and Practices Reflect Regulatory Context



Note to Reader:

The Clean Water Act turned 40 years old in mid-October. In that time, waterways in the U.S. have become cleaner. “Urban waterways have gone from being wastelands to being the center of redevelopment and activity,” writes Gregory DiLoreto, president-elect of the American Society of Civil Engineers (ASCE). “The end result — waters are more swimmable, fishable and sources of drinking water are more protected.”


Understand the Historical Context

The history of the American Clean Water Act it is that legislative action was necessary to undertake a massive cleanup of pollution that had been accumulating in American waterways for many decades. A call to action resulted when the Cuyahoga River in Ohio caught fire in 1969.

Understanding the historical context is important because the nature of rainwater management in British Columbia is quite different from that in the United States. In the 1990s, the call to action in British Columbia resulted from the loss of habitat and headwater streams due to urbanization of the surrounding landscape.

Jim dumont (120p)“The approach we have taken differs from that of the United States due to the nature of the root problems being solved,” explains Jim Dumont, Engineering Applications Authority for the Water Balance Model Partnership . ”The critical issue in British Columbia is the damage and loss of habitat caused by development and erosion of the headwater streams. The Americans have focussed upon water quality in the main stems and coastal waters.”

“Perhaps when the focus of the United States Environmental Protection Agency (EPA) shifts from water quality to include habitat loss, the Americans will review the lessons learned in British Columbia and incorporate them into their policies and objectives. Perhaps such integration could lead to their next evolution in creating a greener and more sustainable environment,” adds Kim Stephens, Executive Director, Partnership for Water Sustainability in British Columbia.


To Learn More:

To read an article co-authored by Kim Stephens and Jim Dumont that was published in the November-December 2011 issue of Stormwater magazine, click on Rainwater Management in a Watershed Context – What’s the Goal? For background on the article, click here to read a story posted on the Rainwater Management community-of-interest.


A Science-Based Road Map for Integrated Rainwater Management

A guiding principle is that appropriate regulations, tools and practices for integrated rainwater management be science-based and reflect the goals for watershed sustainability.

In 1996, the landmark findings of Richard Horner and Chris May provided a science-based road map for integrated rainwater management. Their seminal paper identified the four factors limiting stream health in order of priority as listed below. A key message was this: get the hydrology right and water quality typically takes care of itself.


Implementation of Water Balance Methodology

“The insights resulting from an understanding of the four factors led the Province of British Columbia to develop the Water Balance Methodology and initiate  a paradigm-shift in the way rainwater is managed. The methodology is the technical foundation for Stormwater Planning: A Guidebook for British Columbia, released in 2002,” reports Ted van der Gulik,Chair of the Water Balance Model Partnership.

“British Columbia was the first provincial or state government in North America to implement the Water Balance Methodology. Looking at rainfall differently led directly to development of the Water Balance Model and, more recently, to the Water Balance Model Express for Landowners.”

“The Water Balance Methodology is a foundation block for those tasked with developing a Master Drainage Plan, an Integrated Stormwater Management Plan (ISMP), the Rainwater Management Component of a Liquid Waste Management Plan, or a Watershed Blueprint,” continues Richard Boase, Co-Chair of the Water Balance Model Partnership.

“Once all BC land and water practitioners in the local government setting fully grasp why we have fundamentally different goals and a different starting point from the United States, then there will be a shared realization that the solutions also need to be different. Because the solutions are different, then the tools also need to be different; and furthermore, the tools need to be tailored to meet our needs and resolve our issues. This understanding provides the backdrop for creation of the Water Balance Methodology and Model.” 


“Match the Model to the Goal,” reminds Dr. Charles Rowney

“Watershed and drainage models are not a ‘one size fits all’ item.  These tools each have pluses and minuses, and tend to reflect the regulatory and physical context for which they were first developed,” states Dr. Charles Rowney, Scientific Authority for BC’s Water Balance Model Partnership.

“Even the modellers who use them very effectively can have unconscious biases which reflect from the places they practice and the tools they use.  This is probably a great place to remember the old saying, that ‘if you have a hammer the whole world looks like a nail’.  So the challenge we face is to find modeling technologies that are right for our needs, the solutions we prefer, and the processes we have developed.”

“The patterns of development and growth in BC stress fresh and coastal waters in ways that, in sum total, are particular to this region.  It is crucial that we look clearly at this picture, understand what is needed, and develop technologies that fit those circumstances.”

“We have to avoid force fitting something, however good it may be somewhere else, that doesn’t mesh with practices and priorities in this Province.  To meet the procedural requirements that have emerged by consensus in this area, and to preserve the key targets that have been identified, we are determined to develop and make available a technology that is founded on universal sound scientific principles but custom-fitted to this place and time,” concludes Dr. Rowney.


To Learn More:

Periodically, the Water Balance Model Partnership holds a WBM Partners Forum. These gatherings provide an opportunity for local governments to learn from each other, reflect on what has been accomplished through alignment and collaboration. In April 2011, Metro Vancouver hosted the Forum at its offices in the City of Burnaby.

Dr. Charles Rowney, the creator of the QUALHYMO calculation engine, reported out on the implications of computing technology decisions. In providing context for the strategy behind development of the Water Balance Model, Dr. Rowney’s theme was: “The Voice of Experience – What we now know about what drives a successful model”.

To access two relevant stories posted on the Rainwater Management community-of-interest, click on the links below:

Drainage Modelling in the 21st Century: What are the impediments to success?

Drainage Modelling in the 21st Century: The Uncertainty Cascade