This issue is complicated and to say that rain gardens are the answer is not much different than the traditional infrastructure approach, where one solution can solve all problems. In most instances and geographic locations, the solution needs to include water quality and quantity solutions to solve the problem. Rain gardens, bio-swales and previous paving can be used for water quality benefits and storage, regional detention and wetlands are needed to alleviate quantity issues. These are general ideas and need to be site and watershed specific.
If we have relegated any part of this system as unnecessary infrastructure we have already lost credibility with engineers, other designers and policy and decision makers.
I have been fortunate to have the ability to stick my nose into early conversations with engineers or to work on projects where we will drive the concepts and pass the drawings onto the engineers to stamp. This lets the engineers see that landscape architects can actually understand, design and detail holistic stormwater systems into the site, usually in a much more integrated and beautiful way too. This is not always the case and much like the whole system approach to design, landscape architects need to be talking to policy and decision makers (local, state and federal) to inform them of our profession to increase the credibility of the profession. The engineers have been doing this for years; we can always learn something from them!
If you are armed with facts, calculations, great imagery and graphics, the fight, as we call it, is much easier to win. Let’s not forget we will always need to work with our engineer friends on project teams and they do bring valuable expertise to the team. If we can get past titles and just work together to design incredible projects we will ultimately live in a better world.