Low Impact Development (LID) is a term used to designate a suite of development practices that reduce stormwater runoff through conservation and use of existing natural site features integrated with distributed, small-scale stormwater technologies that mimic natural hydrologic processes. One example is found in my posting on the Hoquarton Bioswales below. Bioswales, like riparian areas and natural or constructed wetlands act as “green infrastructure” and help slow, capture, filter, and re-release stormwater that runs off of hard–or impervious surfaces. The greater the impervious surfaces, the greater the stormwater runoff. Stormwater acts as a ‘superhighway’ for transporting pollutants into receiving waters. The more unmanaged stormwater runoff spills into our waterways, the more pollution we see building up in those waters. Hence, even 35 years after the passage of the Clean Water Act some U.S. waters continue to be polluted. The Clean Water Act in effect regulated and reduced the “point” sources of pollution in the United States (such as factories, sewage treatment plants, some farms, etc.), while stormwater-driven “non-point” pollution continues to be a big problem.
The concept of LID and the development of “green infrastructure” ideas (like bioswales) began as a response to worsening water quality in coastal areas such as the Chesapeake Bay area. I just returned from a workshop on the lovely shores of that bay and found it to be an overwhelmingly complex watershed (from a management point of view). According to the EPA, over 64,000 square miles of land drain to the Chesapeake Bay. Population in the watershed exceeds 16 million and is projected to surpass 19 million before 2030. Excessive loads of nutrients and sediment have been identified as primary causes of Bay degradation. From 1985 to 2005, EPA estimated loads from developed land sources increased up to 16 percent, while loads from wastewater disposal and agriculture decreased.
Unfortunately, it looks like even the innovative push to implement LID hasn’t been enough for the beleaguered Chesapeake. In a report to Congress, the U.S. Environmental Protection Agency’s (EPA) Office of Inspector General (OIG) says new development around the Chesapeake Bay is increasing the runoff of excess nutrients and sediment at rates faster than restoration efforts are reducing them. As a result, the EPA and its Chesapeake Bay watershed partners will not meet nutrient and sediment load reduction goals for developed lands by 2010 as established in the Chesapeake 2000 Agreement, according to the OIG. This review, released Monday, is one of several conducted by the OIG in response to a congressional request. In the report, the OIG recommends that the EPA “prepare and implement a strategy that demonstrates leadership” in reversing the trend of increasing nutrient and sediment loads from developed and developing lands and should establish a stormwater permitting approach that achieves greater nutrient and sediment reductions. The EPA concurred with the recommendations in this report.
The 35-page report describing the scope of the mighty Chesapeake Bay’s problems can be found at: http://www.epa.gov/oig/reports/2007/20070910-2007-P-00031.pdf.
This doesn’t mean that the quest for LID and its hoped for reduction in stormwater-transported pollution is over–but perhaps at the scale of the Chesapeake, the technologies just aren’t enough to keep up with the accumulated impacts of 16 million people and their land uses. Here on the North Coast of Oregon–and even inland along the Lower Columbia and Willamette rivers, we have a chance to do things right–perhaps by implementing LID into almost everything we develop before we get to the point of no return. Let’s not give up the quest for clean water yet.