We received this email a few weeks ago and I wanted to take the time to answer it here.


I’d like your opinion on what seems to be a discord between practitioners and advocates of LID, Low-Impact Development or Green Infrastructure, techniques to manage stormwater and water quality, and practitioners and advocates of New Urbanism.

Both seem to be viable alternatives to our current patterns of development, land and resource use. Although, my concern with the latter is that it often ends up producing only very expensive housing.

In any case, LID is an essential component in moving into a sustainable future.  It also fits quite well with returning roads to community streets.  There really should be no contention or disagreement between LID and New Urbanism.  It would be unfortunate if this chasm were to continue unnecessarily.

Thank you,

Ann P.

I may disappoint you, Ann, along with others who may hold Low Impact Design and Green Infrastructure in high esteem. I have no such inclination myself.

First, let's get on the same page as to what is meant by Low Impact Design (LID) and Green Infrastructure. Both are very concerned with the management of stormwater, with a secondary concern (and my experience has been that this is a FAR secondary concern) being habitat preservation. From Wikipedia (which I think is fairly accurate), some of the benefits of LID are described as:

...protecting animal habitats, improving management of runoff and flooding, and reducing impervious surfaces. LID also improves groundwater quality and increases its quantity, which increases aesthetics, therefore raising community value.

LID can also be used to eliminate the need for stormwater ponds, which occupy expensive land. Incorporating LID into designs enables developers to build more homes on the same plot of land and maximize their profits.

My skepticism toward LID is based on my observation of how it has been applied. 

First, I see LID being applied almost exclusively to new projects, which are largely themselves on greenfield sites. The stormwater ponds and other such approaches are used to mitigate the negative impacts of the development. This is a sub-optimal outcome because, in almost every instance I have ever seen, the development is the result of a series of government policies that favor greenfield development.

These tend to be poor compromises that ultimately have little impact. Over time, stormwater areas made with pervious pavers or other pervious materials lose their capacity. Ultimately they will fail. There is no mechanism built into any local bureaucracy for measuring their rate of decline or replacing them with materials of similar performance once they do fail. So we ease our conscience a little bit when we require these things, but long term, it only enables bad development.

Which is really the main reason why I have no love for LID. I can't tell you how many times I have been at a meeting where a developer comes in with a terrible project that has been "greenwashed" (I don't like the term, personally, but it makes the point here) by having all of the LID elements in place. Or the LEED certification, for that matter. (Check out Kaid Benfield's post on how the EPA pulled this on their new remote campus in Kansas City). At that point, we're just mitigating negative impacts. I prefer avoidance.

So how would we avoid them in the first place? Well, since we have more infrastructure than we have the capacity to maintain by a startling margin, I would focus development on our core cities where we already have the infrastructure investments in place. Unfortunately, the LID advocates often oppose that type of development as well.

I often point out how the new, sprawling campus that the county built in my hometown comes complete with a nature band aid; rain gardens in the middle of the downtown. Personally, I would rather use that space to build some good urban structures that could house people and businesses and take some of the pressure off the real wetlands we are filling on the periphery of town. (In fact, it should be noted, I would end all of the subsidies of those structures on the periphery and, if that were done, few would ever be built.)

Again, I can't tell you how many meetings I have been at where the LID advocates show up and demand certain checklist items, not understanding the overall context of the site. The two block comparison I wrote about to start the year is a prime example. You have a project that devolved the city, eroded the tax base, reinforced the auto-dependency of the community and the environmentalists were happy with it because it had stormwater retention ponds. That's one dimensional thinking, and it's not good enough.

So I think LID enables the worst kind of development, and really is not that low impact over the long run. Yes, if you insert me into a design review process where the site is set, the building is set and all we are doing is reviewing their site plan, I would push for all of the mitigation efforts I could. Great, but that is a little like Moses advocating for condoms once someone decides to commit adultery. There is a reason the ten commandments are short; they are not encumbered with a lot of nuance. 

Maybe we need nuance, and if we do, LID can be it. As for is being a governing philosophy or an optimal approach, it is clearly not.

Neither is New Urbanism, for that matter. At least not the "build a better suburb" type. But if you had been in West Palm Beach last week hanging out with me and the other NextGen of the New Urbanists, you would see that the better bad approach is completely out of favor. There is little tolerance amongst the new flock for the lesser of two evils. Amen to that.

I would strongly recommend reading the work of Steve Mouzon, particularly his book The Original Green. In that, he talks about the way our ancestors used to live and, guess what, it was a lot softer on the environment than what we do today (gadgets, gizmos, gimmicks and all).

Our cities are in the early stages of contraction, with exurbs being the first place where it is really manifesting itself. (Incidentally, I'll be on Minnesota Public Radio this Friday talking about the future of the exurbs -- 9AM CST at MPR.org). I don't want LID to get in the way of building productive places within our core cities and neighborhoods. Concurrently, I want our countryside to return to the low impact pattern of development that dominated North America until recent decades. I think both are likely to start happening as soon as we come to grips with the fact that we can't afford to fix our highway system.

Ann, I know your question was asked with all sincerity. I think we want the same thing and I hope that my lack of support for LID does not keep you from working to build a strong town.