Long time NALMS member, consultant, and past speaker at NECNALMS Dick Osgood has published a paper on the inadequacy of normal best management practices (BMPs) to restore eutrophic lakes to compliance with water quality standards. Dick’s paper, in the September issue of Inland Waters, is based on a review of many restoration efforts, documenting an opinion held by a number of long-term practitioners in lake management for some time. In essence, the degradation caused by development and agriculture in many lakes is not sufficiently counteracted by BMPs as applied in actual cases.
In some cases the application has not been at a scale sufficient to reduce loading enough to meet standards, but in many cases even maximum application is not enough to offset the inputs from the watershed. Where the ratio of watershed to lake area is <10:1, the probability of success through watershed BMPs increases, but there are few cases of success where the ratio is larger. Most BMPs reduce loading by no more than 50%, while development and agriculture tend to increase loading by tenfold or more.
While the paper is new, the debate is not, and there has been considerable defensive posturing by watershed management enthusiasts and institutions. But this paper is not saying that watershed management can’t work, only that we have been unsuccessful applying it in a manner that leads to success. Some of this is a result of technical limitations (e.g., heavily urbanized watersheds will never function like natural landscapes), but a lot of it is related to institutional failure (e.g., lack of funding, regulatory restrictions, inadequate jurisdiction). And if what we desire is success, measured as compliance with water quality standards for lakes, we need to do what works, not what is philosophically satisfying, politically popular, or simply affordable. In-lake management does not guarantee success, but has a better track record than watershed management. Some combination of watershed and in-lake methods is likely to be needed in most cases, but it seems clear that in-lake management deserves more attention than it has been given in many years by agencies responsible for environmental management and regulation.