Kerr Wood Leidal Associates Ltd.1
Introduction
The lower third of ecologically rich Partington Creek watershed is planned for a $1.5 billion community development. Over the next 20 years, what is now forested hill slopes will become a new town centre, home to about 12,000 people.
The City of Coquitlam (City) commissioned the Partington Creek Integrated Watershed Management Plan, which charts a new and better way to plan sustainable communities. The common approach to land development is to first create land use plans and then engage engineers to lessen the negative impacts of development. This reactive approach limits the opportunities to successfully integrate urban development, local community goals, and protection of ecological values. (France, 2002) The result has been inadequate and costly mitigation plans, and urban developments that harm adjacent watercourses and their aquatic life. (Gurnell et. al., 2007)
The processes of land use planning, watershed planning, and financial modelling should be done concurrently, not sequentially. The Partington Creek process accomplished this. The multidisciplinary team of planners, engineers, biologist and financial professionals worked together and changed the initial land use plan to maximize environmental protection and rainwater management potential. Land use designations were redrafted to strategically minimize impacts to the creek and optimize stormwater infrastructure. As well, the most valuable fish habitat along Partington Creek will be enhanced to achieve a net environmental benefit.
Need for Watershed Management Planning for Partington Creek
The Partington Creek watershed is an undeveloped "greenfield" mountainous watershed that is predominantly covered in second growth Douglas Fir forest. The 625 ha watershed is located on the lower slopes of Burke Mountain in Coquitlam, a suburb of Vancouver, British Columbia, Canada. Partington Creek is one of the last ecologically healthy watersheds and streams in the Metro Vancouver region. (Catherine Berris Associates, 1995) The streams provided habitat for Pacific salmon species (MoE, 2009) and many aquatic species-at-risk such as white sturgeon, Dolly Varden and coastal cutthroat trout. (BCCDC, 2009) The lower reaches of Partington Creek flow through the Pit River lowlands, prime agricultural lands in the region.
The proposed Partington Creek Neighbourhood development will result in between 3,500 to 5,700 new residential units resulting in estimated population of between 10,000 to 15,000. This development will result in increasing total impervious area of the watershed from 2% under current conditions to 22% in future.
The identification of potential negative impacts of development on key fish habitat and potential increased flooding risk to downstream agricultural lands were two of the initial drivers for the City to implement the watershed management planning process.
Integrating Community Engagement, Land use planning and Watershed Management Solutions
The project proceeded in several phases over six years from 2005 to 2011, and involved the concurrent preparation of the Integrated Watershed Management Plan (IWMP) and the Partington Creek Neighbourhood Plan (PCNP). One of the key drivers of planning process was collaboration between the land use planers, stormwater engineers and professional biologists. For example, during completion of the field investigation in the initial phases of the project, small watercourses not previously identified were located and mapped. Through this process, a network of small, seemingly insignificant watercourses where identified that flow through the originally planned high density town centre. Habitat assessments identified that these streams were, in fact, a network of ephemeral headwater streams that provide an important food source to downstream fish habitat. As a result, the land use planning team investigated alternative locations for the town centre, with input from stormwater engineers and biologists. This has resulted in the planned town centre being moved to a less ecologically sensitive location.
Project Achievements
The IWMP calls for sustainable infrastructure that goes well beyond regulatory requirements in preserving this undeveloped watershed's ecology. The key features of the plan are:
Integrating land use planning with stormwater engineering. Various land use types were changed and placed in strategic locations to minimize impacts to the watercourses and maximize the space for stormwater source controls without compromising on the densities, liveability or economic viability of the development. Regional stormwater facilities will be located on proposed school and park sites.
Enhancing the best fish habitat in the watershed The proposed floodplain and channel enhancements in Partington Creek will be accomplished by moving a 1.5 km of existing roadway away from the existing creek channel to create 30-metre wide riparian setback zones. This has multiple benefits such as reduced flood levels, increased sediment management areas, increased area for riparian vegetation, and instream habitat complexing. These measures will provide significant ecological health gains for the watershed, and a net environmental gain for fish and fish habitat in the watershed.
Mitigating the impact of development through leading-edge stormwater technologies, including engineered underground baseflow augmentation facilities, which will mimic the natural hydrologic processes in a watershed and sustain aquatic life. This new technique uses specialized flow splitters such that baseflows, low flows and flushing flows continue to the natural creek system. Unlike surface ponds, which are common practice in stormwater management and are heat sinks that can warm creek systems to fish-harming levels, these underground rock trenches will keep water temperatures cool for fish. The land area above them can be used for recreational uses.
Conclusions
The Partington Creek IWMP was initially commissioned by the City of Coquitlam to address concerns relating to potential negative impacts of proposed land development on key aquatic habitat in Partington Creek and potential flooding of adjacent agricultural lands in Pitt River lowlands. However, unlike similar reactive stormwater management planning processes, the concurrent development of the PCNP land use plan and IWMP watershed plan, allowed for collaborative environmental, engineering and land use planning decisions resulting in a single comprehensive sustainable vision for the watershed.
The planning process has preserved watershed health as a whole, while meeting community needs and allowing development to occur. Using a progressive approach of iterative collaboration among stakeholders, planners, engineers, biologists, and financial professionals, it was possible to create a more sustainable and economically viable community.
Catherine Berris Associates Inc. (1995) Northeast Coquitlam Environmental Assessment. Unpublished report prepared for City of Coquitlam. 44 p.
B.C. Conservation Data Centre. (2009) BC Species and Ecosystem Explorer. B.C. Mininstry of Environment, Victoria, BC. Accessed Oct 12., 2009.
Ministry of Environment. (2009) Fisheires Inventory Data Querries. B.C. Mininstry of Environment, Victoria, BC. Accessed Oct 12., 2009.
France, R.L. (2002) Handbook of Water Sensitive Planning and Design. Integrative Studies in Water Management and Land Development; CRC Press: Boca Raton, FL, USA.
Gurnell, A.M., Lee, M. and Souch, C. (2007) Urban rivers: hydrology, geomorphology, ecology and opportunities for change. Geography Compass 1:1118–1137.