General Stormwater Management Information

The need for stormwater management:

“Stormwater management is the planning, design and operation of systems that store, convey, and treat stormwater runoff. By controlling runoff, mitigating flooding and preventing pollutants from entering water bodies, effective stormwater systems can minimize adverse impacts to communities and the natural environment. 

With fast-paced population growth, loss of natural areas, and increased development being a common reality for many Alberta communities, concerns related to stormwater management have heightened. With development, more land coverage by impermeable surfaces contributes to increased runoff rates, volumes, and pollutant loadings. These changes can contribute to the degradation of water quality and aquatic ecosystems, urban flooding, erosion and sedimentation, infrastructure deterioration, property damage, and public health risks (AUMA, 2014 Municipal Water Policy on Stormwater[1])”. 

In the CSMI region, urban flooding has become an increasingly greater issue. Every spring, residents and businesses are forced to manage flooding on their properties. This can be due to the lack of stormwater management systems in place to drain stormwater away. 

The CSMI region is unique, in that many of the major stormwater drainage corridors are part of the Western Irrigation District works. In some areas, these drainage pathways are natural streams, and in others they are man-made canals. In all cases, farmers use this water to irrigate their crops, with farm lands located all throughout the WID canal system. Managing stormwater from adjacent lands and from urban developments is important to ensure water entering the streams and canals, has a quality that is adequate for crop application, and also for protecting the natural stream ecosystems. Appropriately managing storm surges also prevents erosion of natural stream banks caused by the significant forces of large volumes of flowing water. 

The CSMI is taking steps to ensure appropriate stormwater management is implemented to protect communities and the watershed within the CSMI region.

To learn more about stormwater, visit the Alberta Urban Municipalities Association website here:

How is stormwater management planned for in Alberta?

CSMI Stormwater development path
Figure 1. Alberta Stormwater Plan, Development Path

Figure 1 shows the current stormwater planning process in Alberta. Planning begins at the highest planning level for the entire river basin, followed by development of a water drainage plan, a master drainage plan, and finally a site implementation plan. This process is required for all developments in Alberta. 

The CSMI is unique, in that it covers a very specific geographical area. The assessments carried out to determine feasibility of stormwater management system in the region are aligned with both the water drainage plan and master drainage plan activities.


What is an off-site levy? 

Off-site levies will be required by developers to help to pay for any stormwater management infrastructure implemented by municipalities in the CSMI region to help to pay for that infrastructure.

The Municipal Government Act (MGA) enables municipalities to regulate development by allowing the enforcement of legislative tools and allowing them to acquire financial contributions towards stormwater system infrastructure through the assessment of levies and taxes (AUMA, 2014 Municipal Water Policy on Stormwater).

An off-site levy is a charge established by a municipal bylaw, imposed as a condition of approval for some developments. Through an off-site levy, the developer of subdivisions, developments and redevelopments bear a fair portion of the cost of constructing or expanding certain municipal infrastructure facilities such as roads, water lines/treatment/storage and sewage facilities/ lines, stormwater facilities, and other municipal services.  

Thus, an off-site levy helps pay for municipal utility systems required outside or "off" the site of a particular development, that directly or indirectly serve that development.

The payment of an off-site levy is a one-time requirement, and can only be required for the development or subdivision of land. 

Engineering and financial studies of the infrastructure required to support and maintain cost effective and orderly growth are typically undertaken by the municipality to establish the off-site levy rates. Payments by developers and people subdividing land are typically based on an amount proportionate to the area being developed or subdivided. Municipality review levy rates periodically to ensure they are appropriate for current construction costs.