All the costs considered below assume the stormwater wetland would be built or retrofitted into a stormwater detention facility. Moving soil  or building a wetland from scratch is also not included in the estimates below.

• Design and Engineering: as high as $8,000-$15,000 per acre
• Grading: an additional 5-10%
• Retrofit grading and construction: $5,000-$15,000 an acre
• Installing vegetation: $10,000-$20,000 an acre
• Outlet structure construction: $10,000-$15,000
• Overall cost for wetland in a detention basin designed for a wetland: approximately $40,000
• Overall cost for a retrofit wetland: $50,000

Maintenance is similar to that of a pond. Periodic dredging (every 2-5 years) would be required to maintain the depth of the small forebay. Vegetation would have to be managed, such as assessing the survival of the different plant species and removal of plant species known to harbor mosquitoes. It is best to design the wetland so it periodically dries out and can be mowed to control brush. Alternatively, a permanent inundated wetland also helps to reduce brush infestation.