The Marshall Springs project is part of a larger program of stormwater quality retrofit projects intended to reduce contaminant loads to rivers and creeks in Calgary.  Located in Fish Creek Provincial Park, Marshall Springs includes a 20+ ha pond, diverse wetland habitats and infiltration within conserved natural habitat areas.  Serving a residential catchment area of 490 ha, the facility will divert and treat the full volume of a 1 in 5 year 24-hr duration storm, approximately 76,000 m3.   The project is a prime example of the site-specific nature of stormwater retrofit projects.  The design of the new facility has been driven by diverse environmental, physical and societal functions and values. Many of which relate to the aquatic and aesthetic importance of the Fish Creek Valley, an extensive natural space corridor in South Calgary.