The data acquisition necessary for the development of this contribution was the first step in the process of designing and implementing a management plan for the Otsego Lake watershed. The second, now ongoing, is to gather information regarding citizen concerns, perceptions and agendas about this resource. Without the latter input, the political will to support any plan would be lacking and the effort would surely languish without timely and effective implementation.
Information gathering from the citizenry also provides the socio-political attributes to the ecosystem scenario, such as safety and aesthetic values, that are paramount to any planning effort but are beyond the scope of this report.
A majority of the changes most seriously affecting the recreational use of Otsego Lake over the last 30 years have been the direct result of introductions of exotic organisms. From an ecological perspective, Otsego Lake is not the lake it was even 20 years ago, and it is very unlikely to return to those conditions. Change is a characteristic of inland bodies of water. And the introductions causing some changes are not always negative. But chronic attacks by one invading species after another preclud es even the ephemeral stability necessary to maintain an ecosystem's integrity and sustainability (Woodley et al., 1993). These changes compromise the characteristics that enable the resource to remain an asset to the community, both ecologically and economically.
There are several species of exotics in New York State waters that are serious pests that have not yet appeared in Otsego Lake. More will continue to invade the State as commercial and recreational activities increase their motility. It is important that any management plan include recommendations for measures to reduce the probability of successful colonization into Otsego by these organisms.
An even more important component of any management strategy to ensure the present viability of this resource is to implement means to reduce phosphorus loading and availability. The data presented in this report not only document an enhanced rate of eutrophication, but reveal a situation that pleads for timely and effecti ve action.
There are indications that a feed-back phenomenon has been initiated that can rapidly increase the rate of internal phosphorus loading. There are increasing hypolimnetic oxygen deficits, most manifested in decreased late summer, deep water dissolved oxygen concentrations. Concurrently, there has been a recent (1995) increase in total phosphorus in bottom waters derived from sediments during late summer stratification. Sediment-bound phosphorus can be released into hypolimnetic wa ters during periods of anoxic or near anoxic conditions. Following overturn, it is made available to organisms. Increases due to internal loading can be extensive enough to render ineffective comparatively inexpensive, normally recommended non-point source pollution strategies to minimize in-lake availability of phosphorus (Bostrom et al., 1982; Carr, 1962; Cooke et al., 1993; Cullen and Forsberg, 1988; Sas et al., 1989). These include land use regulations including provisions for nutrient management, agricultural "Best Management Practices" and recreational use legislation. We assume that there is still an opportunity to reverse this trend. However, it is not known how long it will take for conditions to deteriorate to the point where conventional watershed-oriented mitigation is ineffective.
Aside from the ecological impacts of increasing eutrophication, the importance of protecting Otsego Lake's quality is paramount with regard to it being the primary potable wat er source for the Village of Cooperstown and many lakeside residences. Eutrophic conditions not only impart undesirable tastes, odors, and colors to water, but associated organic molecules may react with chlorine during disinfection processes to form potentially carcinogenic or mutagenic trihalomethanes (Cooke et al., 1993). Additionally, there is evidence of gastrointestinal disorders related to the consumption of water derived from surface sources experiencing blooms of blue-green algae, whi ch often are associated with increasing eutrophy (Carmichael, 1985). Increased operating and maintenance costs by water treatment facilities necessary to manage the above problems are significant.
If Otsego Lake is to retain the characteristics that have made it the environmental and cultural focus of human endeavor in our region, it is imperative that existing phosphorus sources, as well as those resulting from actions that could increase its loading or availability, be aggressively mitigat ed.