A quick glance at the graph on the effects of imperviousness on watershed scale will tell you that preserving watersheds with relatively low imperviousness will provide a better return in the long run for water quality than decreasing the imperviousness of a watershed that has 60 percent imperviousness to say, 40 or 50%. That 10 or 20% decrease would be quite costly in terms retrofits, etc., and still the watershed would be substantially impacted.
The first step any community must take is to determine which watersheds are relatively un-impacted (e.g., have low imperviousness), and then to identify and prioritize areas for preservation. Not all open space is equally beneficial in terms of water quality. Areas with abundant wetlands or standing forests are much more functional in terms of water quality than recently abandoned agricultural fields, for example. Identifying these areas is the easy part! Figuring out how to get targeted properties into the public domain is a bit more tricky! Outright purchase, however, is not the only way to preserve land.
The Economic and Ecological Value of Open Space
The Lincoln Land Institute web site is packed with excellent information of the value of open space and how to get open space into the public domain.
The Economic Value of Open Space from the Lincoln Land Institute is an excellent example of the kind of publications available.
The Conservation Fund’s Green Infrastructure Leadership Program provides valuable information on green infrastructure, what it is, why it matters, and how it is achieved.
The GreenSpace Alliance and the Delaware Valley Regional Planning Commission (DVRPC) recently released a report that is the first to quantify the economic value of protected open space in the southeastern Pennsylvania area. A summary of the report, called Return on Environment can be accessed here. The President of Natural Lands Trust, Molly Morrison, appeared on Comcast Newsmakers recently to discuss the study.
Other publications that provide valuable information on land preservation and conservation:
Regional Trusts Serving Galveston County
Statewide Land Trusts Serving Galveston County