Rainwater Management in the 21st Century: Application of the “DFO Urban Stormwater Guidelines” has evolved over the past decade to protect stream health
Note to Readers:
The following story is extracted from Chapters 5 and 7 of Beyond the Guidebook 2010, released in June 2010. This water-centric guidance document tells the stories of how change is being implemented on the ground in BC. The following story provides context for the “DFO Urban Stormwater Guidelines” – how they set a direction in 2000; how they have evolved into “Beyond the Guidebook”; and how the Water Balance Model is a tool to correlate runoff volume management with stream erosion and water quality outcomes. The goal is protect stream health.
“DFO Urban Stormwater Guidelines” set a direction in 2000
“We are moving from guidelines to tools,” states Corino Salomi. He is Area Manager, Oceans, Habitat & Enhancement Branch, Lower Fraser Area. He represents the Department of Fisheries and Oceans (DFO) on the steering committees for both the Green Infrastructure Partnership and the Inter-Governmental Partnership (IGP) that developed and maintains the Water Balance Model.
“It helps to look back to understand how we got to here. In November 2000, DFO released the 4-page Urban Stormwater Guidelines and Best Management Practices for Protection of Fish and Fish Habitat, Draft Discussion Document. That document set a direction. It got practitioners thinking about how to capture rainfall in order to reduce runoff volume and protect water quality.”
“By 2007, however, we had concerns about how the document was being interpreted and applied. Beyond the Guidebook 2007 represents the initial course correction. It introduced a science-based analytical methodology that enabled local governments to explore the requirements for stream health protection. This methodology is now embedded in the Water Balance Model. “
To Learn More:
Click on Moving from Stormwater Management to RAINwater Management: A Federal Fisheries Perspective — At the Beyond the Guidebook Seminar in November 2007, a key message was that RAINwater management is about protecting stream health, not just how much runoff volume can be infiltrated.
Establish Targets that Make Sense
“The purpose of the Beyond the Guidebook initiative is to help local governments and the development community establish what level of rainwater runoff volume reduction makes sense at the site, catchment and watershed scales. The objective is protect stream health, which is broader than how much volume one can infiltrate on a particular development,” emphasizes Corino Salomi.
“The pilot for ‘going beyond the Guidebook’ was the City of Surrey’s Fergus Creek watershed plan. This formalized the Stream Health Methodology that is incorporated in the advanced application of the WBM,” continues Jim Dumont, IGP Engineering Applications Authority.
“The methodology is a function of flow duration. This enables us to correlate green infrastructure effectiveness in protecting stream health. The reason is that rainwater runoff volume management is directly linked to stream erosion and water quality.”
“Beyond the Guidebook enables practitioners to make a clear distinction between a rainfall-based approach and a runoff-based approach. The latter leads to analysis of runoff interaction with the physical aspects considered important to the aquatic environment.”
“In 2008, release of the Commentary on Effective Muncipal Rainwater-Stormwater Management and Green Infrastructure to Achieve Watershed Health was a first step in helping local governments make the needed course correction. It presents a conceptual framework for setting watershed-specific targets and then implementing them at the development scale. Now we need to go the next step,” continues Corino Salomi.
“We have tools such as the Water Balance Model and the Topsoil Primer Set; and we have many on-the-ground examples of how to capture rain where it falls. Municipalities just need to get on with applying the tools and the experience so that they capitalize on opportunities rather than missing opportunities.”
To Learn More:
To view a 3-minute video clip on YouTube that features Jim Dumont explaining the runoff-based approach, click here. The methodology embedded in the Water Balance Model enables a watershed target to be established. It also enables the user to assess how to meet the watershed target at the site scale.
Stream Health Protection
“The science-based analytical methodology that has been validated through the Fergus Creek pilot enables local governments to explore the fundamental requirements implicit in the DFO Guidelines for stream health and environmental protection,” summarizes Jim Dumont.
“The validity of this thinking is reinforced by what the Bowker Creek Initiative in the Capital Region has demonstrated, and what the Metro Vancouver Reference Panel is now telling us. Establish the vision, set the target and then implement,” adds Corino Salomi.
“Stream health protection is a driver for Beyond the Guidebook. Stream health is a function of flow duration, and therefore correlates with stream erosion. Flow duration is something that we can measure and verify. We can also assess the potential for erosion or sediment accumulation within a watershed,” concludes Richard Boase, Co-Chair of the Water Balance Model Partnership.
To Learn More: