Stormwater—the rainfall and other sources of water that are not absorbed by the ground—flows from areas such as streets, parking lots and roof drains on houses and other buildings. Stormwater may look clean but it can contain motor oil, gasoline, sediment, fertilizer and other contaminants. Traditionally, stormwater management dealt mainly with conveying the excess runoff through a drainage system to the nearest waterway. Today, stormwater management is evolving to integrate stormwater infrastructure planning with relevant municipal planning processes - such as Official Community Plans, Neighbourhood Concept Plans, recreation and parks plans, and even strategic transportation plans - to address impacts of rainwater on community values.

Municipal role in stormwater 
Local municipalities operate and maintain the storm sewer systems that carry stormwater from private property to the nearest waterway.

Some examples of municipal stormwater efforts include:

• bylaws that encourage more natural drainage in new developments
• street sweeping and storm drain cleaning
• creek and watercourse maintenance as well as stream enhancement to improve habitat for aquatic life
• stormwater quality and quantity monitoring
• education programs (e.g. yellow fish storm drain marking to remind residents that materials dumped into storm drains can kill fish and damage habitat)

Metro Vancouver's role in stormwater
Some regional stormwater management policy and planning services are provided to member municipalities as part of the region's Liquid Waste Management Plan. Under the LWMP, the Stormwater Interagency Liaison Group (SILG) was created to facilitate municipal stormwater management activities, and to research sustainable stormwater management practices. SILG developed a stormwater planning guide that is available for municipalities to use while developing long-term integrated stormwater management plans. SILG also developed guidelines for green infrastructure and other tools to assist local governments efforts in sustainable stormwater practices.

Drainage Area Management
In consultation with the affected municipalities, Metro Vancouver currently provides planning and operations services for two key watershed drainage areas:

• the Still Creek - Brunette River Drainage Area (the Brunette Basin)
• the Port Moody - Coquitlam Drainage Area.

Metro Vancouver’s responsibility in these areas is to prevent flooding by ensuring that culverts, creeks, and grills are kept clear and functioning properly. These two areas have highly developed land bases, and stormwater runoff can be significantly affected by moderate to heavy rain storms.

Brunette Basin Coordinating Committee
During the creation of the Liquid Waste Management Plan, a pilot watershed group was established to create a watershed management plan for the Brunette Basin. Based on its success in that project, the group continues to operate today with a mandate to coordinate municipal and stewardship activities in the watershed. The BBCC has facilitated the development of several watershed plans.