Lake Health and Human Impact

Why do we care about the water like the Belgrade Lakes?

 “If there is magic on this planet, it is contained in water.”

-Loran Eiseley

Water bodies like the Belgrade Lakes of Belgrade Maine are epicenters of local activity. They are sources of recreation, tourism, local industry, and natural beauty. It is because of this local importance that special attention has been paid the protection and monitoring of these systems. Through this connection the members of the Belgrade Lakes community have developed a “sense of place.” This is essentially a strong link between the health of the ecological community, and the community of people who enjoy the region. As put by Polly Beatie, a member of the Belgrade Lakes Association board, “if the lakes fail, the community will fail.”

“Water and air, the two essential fluids of which all life depends, have become global garbage cans.”

-Jacques Cousteau

The Hydrologic Cycle

The hydrological cycle is a large complex system that deals with the recycling of water though the various components of the system. On a regional scale, hydrologic systems are directed by localized condition, but these circumstances are ultimately regulated by large-scale conditional patterns. These patterns include latitude, vegetation, land use, geology, insularity, physiographic features latitude, and atmospheric patterns.[1]

As Kenneth Vigil explains in his work Clean Water: An Introduction to Water Quality and Water Pollution Control,  the hydrologic cycle connects all the waters of the world. Precipitation falls and forms streams that become tributaries, connecting to lakes and rivers that eventually assimilate with oceans. From the ocean, fresh water evaporates into the atmosphere, condenses, falls as rain, snow, sleet, hail, or any other form of precipitation, and starts its journey back to the ocean.[2] It is because of this interconnected cyclical nature that water pollution is such an issue. When one chain of the cycle becomes polluted, it feeds into the next, causing a chain of issues.

The next section of this site focuses on the sources of water pollution, and how we can abate and mitigate these sources.

 

Sources and Prevention of Water Pollution

Water bodies are generally categorized based on nutrient levels in the water.[3] There are four trophic states that a lake can be classified as: oligotrophic, mesotrophic, eutrophic, and dystrophic. This is essentially a gradient of plant productivity from very little, to some, to a lot, respectively. In many lake systems, there is a nutrient that restricts the amount of plant growth that can occur. The two most common limiting factors are nitrogen and phosphorous, which we generally test for with chemical means. Algal blooms in lakes have been attributed to higher than normal levels of one of the two limiting nutrients. Though lakes tend to head two a eutrophic state with time, this process can be accelerated through human inputs, leads to what is known as anthropogenic eutrophication. The most common causes of “artificial eutrophication are sewage effluents and agriculture.”[4]

Oligiotrophic lakes are deep nutrient poor bodies of water that tend to be oxygen rich. The second state is mesotrophic, which is the intermediate stage between oliotrophic and eutrophic. These lakes have a moderate sediment input as well as nutrient and plant levels. The Maine Department of Environmental Protection currently classifies great Pond in Belgrade, ME as mesotrophic. Eutrophic lakes are nutrient rich, oxygen poor, and have large numbers of phytoplankton. Finally, dystrophic lakes are characterized by high oxygen levels, low phytoplankton levels, and high macrophyte levels. Essentially, as a dystrophic lake is well on it’s way to becoming a swamp.[5]

Lakes naturally go through these progressions as land based sediment fills the basin with nutrients and fuels the ecosystem, however anthropogenic, or human caused land use in a watershed can drastically alter the inflow of nutrients and sediments. Varying land use will have varying effects on the water body within the watershed. It is at the highest points the catchment area, or the land area that supplies water flow to any given water body, that we define the watershed. This is the area that contains the catchment for a given water body.  Again, the land use within a watershed is of particular concern for the health of the water body within.

It is first important to understand that there is a “background or natural water quality,” that includes the sediments, chemicals, and organisms that would come from water flowing from a forest.[6] This is essentially the baseline, and the changes that are made to the watershed impact this baseline.

Excess water quality pollution from non point sources is of grave concern, as an increase in certain pollutants can actively degrade a lakes trophic status, accelerating it to eutrophic state. The largest threat to lakes is agriculture, followed by municipal point sources, and urban runoff.[7]

There are natural safeguards to the issue of runoff, as buffer strips provide a barrier to nutrients. Buffer strips can control the nutrients that would otherwise enter the water body. Good buffers utilize layering of vegetation, so that a variety of plantings can be used, maximizing the buffer capacity of the strip.[8]

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