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.
The late Stan Dobson, a famous limnologist with a practical interests, gave a talk in 2007 about the measured impact of lawns on water quality in the Madison, WI area. He found that of all the watershed factors one could correlate with measures of water quality, the one that explained the greatest portion of variation in nutrient levels, algae blooms, and loss of species diversity was the percent of the watershed in lawn. Now not all lawns are created equal, and having a grassy area associated with a home or business is not always the worst thing the owner can do, but the tendency to fertilize lawns and the substantial probability that the associated nutrients will reach a downstream waterbody are what make this correlation so strong. Lawns are a very real problem for lakes. They don’t have to be, but they are because of societal “pressure” to manage them in ways that are not good for lakes.
The nutrient issue is exacerbated by lawn care companies that over-fertilize (the chemicals cost less than the labor to retreat if results are unacceptable) and do not scientifically adjust the ratio of nutrients to fit each treated area (can you imagine a lawn care professional in a white lab coat testing soil content before deciding what mix of fertilizer to apply?). People doing lawn care on their own may not be any more responsible. This has resulted in a big push to get phosphorus out of lawn fertilizers, as most established lawns do not need more, and enough towns and even states have banned the use of high P fertilizer on lawns to get the fertilizer manufacturers to voluntarily reduce P content. Measured changes in downstream waters, including some peer reviewed literature (including 2 papers in Lake and Reservoir Management that are freely available), show a significant decrease in P concentration as a result. We still have issues with applied pesticides and nitrogen, but at least the over-application of P is on the wane.
But there is more to lawns than just chemical additives. Creation of lawn to the water’s edge, either at the lake or on any of its tributaries, eliminates buffers for nutrients, sediment, and anything else on the lawn (naturally, not just from additions) and increases loading to lakes. Loss of shoreline structure has been demonstrated (again, check out papers in Lake and Reservoir Management) to reduce species diversity and hurt fish communities and fishing. Loss of vegetative structure away from the water has known negative impacts on terrestrial ecology as well (hey, we can’t be totally lake-centric!). In short, lawns are not good for the environment. They don’t have to be measurably bad, but there is very little to be said in their favor from an ecological or water management viewpoint.
This does not mean that all responsible owners should do away with all lawn area, but it does mean that we should think twice about how much lawn we create and how we manage it. Bob Kirschner of the Chicago Botanical Garden and some other folks associated with NALMS have given some great presentations on how far you can take ecological landscaping before you are perceived as an “irresponsible” citizen of the community by those who look at lawns and landscaping as the taming of nature and a sign of culture. And it is a lot further than many lakefront property owners have gone. Yet there are some great examples out there of ecologically sensitive landscaping and more seem to be popping up all the time. The Maine program called Lake Smart espouses this approach and is achieving some success. New Hampshire and more recently Vermont have shoreland protection legislation that helps, but there is a major need for an education component to attain success, rather than just enforcement. We need to change the way that society perceives developed landscapes, with a focus on lessening impacts on our water resources.
When we speak of lake management goals, we are usually thinking about objectives like maximizing water quality for drinking water supply or contact recreation, improved conditions to enhance fishing opportunity, physical arrangements to increase boating access or enjoyment, or protection of habitat features that support valued wildlife. But it is very hard for a lake to be all things to all users. Not all goals are completely compatible, especially in smaller waterbodies where spatial separation of uses is difficult to achieve. A lake can serve multiple uses, but usually it is necessary to have a priority order for uses and goals, so that conflicts can be resolved.
The cleanest water may be just what we want for a drinking water supply or swimming area, but that water will not support the most productive fishery. A lake with ample facilities for launching big powerboats may not be the best for a peaceful circuit by canoe or for observing wildlife. If the lake is large enough, some segregation of uses can be achieved, and in some smaller lakes temporal separation has been applied, as with early hour restrictions on motors. But the fundamental split between lower nutrients for clearer water and higher nutrients for more fish production is tough to overcome in a single lake. Some reservoirs with the classic elongate and dendritic pattern can achieve some semblance of a desirable range of nutrient concentrations for a range of uses, but stability is hard to maintain.
The best fishing experience does not have to be a simple matter of the number or size of fish caught; an aesthetic place to fish can be an important contributor to enjoyment. Drinking water is treated to meet strict standards in most cases, so the effects of elevated nutrients can be counteracted to some degree. But when conditions shift one way or the other, which goal has primacy will have considerable influence on the actions to be taken. Not all lake management goals are compatible, and this needs to be recognized in planning efforts.