The Stormwater Blogs

More and more communities are adopting green infrastructure and low-impact-development techniques to help manage stormwater runoff—to capture rainfall onsite, to reduce the quantity of runoff that reaches the stormwater system, and therefore to reduce the pollutant load associated with larger amounts of runoff. Some cities with combined sewer overflows are finding green infrastructure a more cost-effective way to deal with the problem than traditional methods, such as trying to separate the storm and sanitary sewers. And a recent report from American Rivers and others demonstrates additional economic benefits of green infrastructure practices.

That’s why it’s so disturbing to see a report like this one, from Maryland, suggesting that many such stormwater BMPs are not properly documented or maintained.

The article describes a survey conducted in the city of Baltimore and nine Maryland counties of 175 stormwater BMPs, many of them LID BMPs such as rain gardens. Forty percent of the BMPs were not well documented in the Maryland Department of the Environment’s database. The consultant conducting the survey found some of them in locations hundreds of feet from where they were described as being; some were different than described, and about a quarter of them were not found at all.

Back in 2002 we published an article in Stormwater magazine that raised the question of long-term inspection and maintenance needs for LID installations. Basically, the article argued that although LID measures like rain gardens, bioswales, filter strips, and so on may perform well at first, they need regular maintenance to continue to do so. They are also by their nature decentralized, unlike most traditional stormwater infrastructure, so inspecting them to make sure they’re operating as they should becomes a difficult task. And it’s not always clear who’s responsible for their long-term maintenance: The homeowners association? The individual homeowners? The city? The author urged that we take a hard look at the long-term performance and fate of such systems before relying on them to reduce runoff.

We got quite a lot of criticism at the time for that article, especially from champions of LID who saw its potential and were trying to educate people and encourage the adoption of what was then, in many places, a relatively new stormwater management concept. Since then, green infrastructure and LID have become increasingly important tools, ones that we’re relying on more and more to control runoff.

As the article on the Maryland BMP survey notes, for some areas the database was better than others—Baltimore city was the worst, with only 13% accuracy, but three counties, including Prince George’s, the “birthplace of LID,” had nearly perfect documentation. So it can be done; perhaps, as an MDE employee says in the article, the database is a “work in progress,” and it’s the documentation rather than the state of the BMPs themselves that needs maintenance. But we don’t know for sure. The article suggests that since some of the counties have too few inspectors—a common situation—they should recruit volunteers to help, such as neighborhood groups and residents.