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Water Quality
How is it measured? What can I do to protect it?
GAUGING WATER QUALITY...
What Does Water Quality Mean?
The essence of water quality is easy to illustrate. Imagine that you have a choice of two lakes near which to live. The first is green, murky, and often too warm for a refreshing swim. Fish are almost non-existent. The second lake is clear, cool and abundant wildlife exists in and around it. Property values on the second lake are much higher than at the first. It’s easy to see which lake you’d choose — the difference is water quality.
Why is Water Quality Important?
Water quality shapes the aesthetics and uses of a lake. A clean, healthy lake will be more suitable for the recreational enjoyment of landowners and visitors as well as for wildlife. Water quality is important not only to our lives, but to the animal and plant species that depend on the lake’s habitat.
When lakes are tested regularly, biologists and volunteers can detect changes in water quality before they seriously impact the lake. Water quality information empowers communities to make informed planning and resource-protection decisions.
How Is Water Quality Measured?
To measure water quality, testing is necessary to gather information about trends and identify changes. When problems are quickly identified, swift action can be taken to protect water quality. Water quality is determined by a variety of lake characteristics — not just how clear the water appears. Measuring temperature, clarity, algae, acidity, and nutrient levels are some of the ways that water quality is determined. Several elements of lake analysis paint a complete picture of lake quality. Many pollutants are invisible, so measuring and monitoring this balance is the first step in preserving water quality and lake habitat.
Clarity is measured using a “Secchi Disk”. This round, black and white disk is lowered into the water and a measurement is taken where it can no longer been seen. The disk is raised until it reappears. The Secchi depth is the point in between these two measurements. From that measurement, clarity is determined. Clarity is influenced by a variety of conditions including weather, microscopic organisms such as algae and plankton, and water color.
Chlorophyll is the green pigment used by plants in photosynthesis. Water samples are analyzed to indicate if microscopic plant forms are present. While these plants are essential to the food chain, an over-abundance of these organisms can result in an algae bloom, giving water an unpleasant taste or odor and decreasing its clarity. When algae die and decay, they drift to the bottom of the lake. Decomposition consumes oxygen in the water and causes other plant and animal species to die.
pH measures the amount of acid in water. Water samples are taken from the lake and analyzed in a laboratory or at the site. Minerals such as limestone, act as a buffer to acid rain. Lakes in New Hampshire are particularly vulnerable to acid rain because they are granite-based and have virtually no buffering capacity. Lakes with a pH of 5.5 and lower are particularly at risk.
Excessive Nutrients from lawn fertilizers containing nitrogen and phosphorus, poorly maintained septic systems, and animal wastes can harm a lake. Although these nutrients are necessary for the growth of plants, large amounts can alter the healthy balance of the lake by causing excessive weed and algae growth.
Oxygen is essential to life — both in the air and in the water. The amount of Dissolved Oxygen is another measure of water quality. An over-abundance of decomposing organic matter such as algae and weeds robs water of much of its oxygen. This occurs primarily in warmer waters. Temperature is also used to help determine the amount of dissolved oxygen. Cold, clear water will have a higher percentage of dissolved oxygen and be able to better support a wide variety of aquatic life. A profile of a lake’s dissolved oxygen content is created by measuring temperature and oxygen at several intervals from the surface of the water to the bottom of the lake.
Water can appear clear and clean but may not provide a healthy, balanced environment for aquatic life. Biomonitoring studies aquatic creatures such as fish and insects to determine their diversity and quantity. A natural balance and diversity of these creatures determines the ultimate health of water — whether it can support vital links in the food chain: plants, insects, fish, reptiles, amphibians, mammals, birds and ultimately people.
How Can I Get Involved?
Volunteer lake monitors are one of a lake's most important allies. Volunteers offer their time and energy working with biologists to regularly monitor lake conditions. Approximately 225 lakes are currently monitored by 950 volunteers statewide.
Two state-wide programs are dedicated to training volunteers interested in protecting lakes in New Hampshire.
In 1978, the New Hampshire Lakes Lay Monitoring Program (NH LLMP) was developed at the University of New Hampshire by Professors A.L. Baker and J.F. Haney. Since 1985, the NH LLMP has been expanded with the addition of Jeff Schloss as coordinator. With site-specific data collected every week at many lake sites during the summer, the research program enables both seasonal and interannual trend analysis of water quality. Hundreds of volunteers have been actively collecting data for more than twenty years. The cumulative and extensive data base enables statistical inference.
In 1985 the Volunteer Lake Assessment Program (VLAP) was initiated by the biological staff at the NH Department of Environmental Services, at that time called the NH Water Supply and Pollution Control Commission. Jody Connors and Bob Estabrook played key roles in the program development. Currently the staff at NH DES trains and assists volunteers with water collection, and analyze samples at the State Labs in Concord. The VLAP program greatly augments the amount of data collection possible, formerly done only by state biologists.
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