Cost issues  

Because of the relative newness of Low Impact Development projects, information about costs is limited and often based on hypothetical models rather than completed projects. Construction costs can be either higher or lower for a LID project than they would be for a conventional development, depending on the site (Dodge 2002). However, overall it appears that LID does pay off financially over the long term. The Low Impact Development Center estimates that, for residential development, LID can lead to

  
   

cost savings of up to $5000 per lot;
reduced site infrastructure and associated costs;
reduced infrastructure maintenance costs; and
potential gains for more lots because of reduced area taken up by infrastructure (i.e. stormwater ponds). (Low Impact Development Center 2000)

  
   
For a 21-acre subdivision in Prince George’s County, MD, development costs for a LID subdivision were estimated to be about 30 percent less than those for a conventional subdivision of similar size. A construction cost analysis study comparing LID development and conventional development yielded the following results (Puget Sound Water Quality Action Team 2001)  
   
 
   
While these long-term financial benefits are important, the aforementioned ecological benefits are even more compelling. LID has the potential to reduce or eliminate runoff from pervious surfaces, thereby enhancing water quality and habitat, and promoting surface water percolation to rejuvenate groundwater supplies.