Results of VLAP Sampling from July 17, 2014

Oxygen, Temperature, and Percent

Saturation Readings

"Definition: Dissolved oxygen or 'DO' refers to the volume of oxygen contained within the water. Much of the DO in lakes comes from the atmosphere, inflowing streams and photosynthesis. Fish and other aquatic life depend on DO to survive. Seasonal changes can affect DO concentrations throughout the year. Warmer temperatures during the summer speed up the rates of photosynthesis and decomposition. When plants and algae die and decompose, oxygen is consumed. This decreases the amount of oxygen, especially in the uncirculated hypolimnion (lower) water layer. In the winter, under ice cover, the DO content can also deplete due to lack of circulation from the atmosphere.

DO levels above 5.0mg/L are considered sufficient for most aquatic life, although some cold water fish species require higher DO levels" *

mg/L = milligrams per liter

*Source: DES VLAP Chemical Parameter Explanations 

*Source: DES VLAP Chemical Parameter Explanations  

"Definition: Turbidity in the water is caused by suspended matter (such as clay, silt, and algae) that cause light to be scattered and absorbed, not transmitted in straight lines through the water. High turbidity readings are often found in water adjacent to construction sites. Also, improper sampling techniques (such as hitting the bottom sediments or sampling streams with little flow) may also cause high turbidity readings. The Class B standard for a water quality violation is 10 NTUs over the lake background level." *

Statistical Summary of Turbidity Values for NH Lakes and Ponds

NTUs = Nephelometric turbidity measurement

*Source: DES VLAP Chemical Parameter Explanations  

"Definition: Conductivity is the numerical expression of the ability of water to carry an electrical current. It is determined by the number of ionic particles present. The soft waters of NH have traditionally had low conductivity values. High conductivity may indicate pollution from such sources as road salting, septic systems, wastewater treatment plants, or urban/agricultural runoff." *

"Note: Specific categories of good and bad levels can not be constructed for conductivity, because variations in watershed geology can result in natural fluctuations in conductivity. However, values in NH lakes exceeding 100 uMhos/cm generally indicate human disturbance."

μMhos/cm = micromhos per centimeter 

*Source: DES VLAP Chemical Parameter Explanations  

"Definition: The chloride ion (Cl-) is found naturally in some surface waters and groundwaters and in high concentrations in seawater. Research has shown that elevated chloride levels can be toxic to freshwater aquatic life. in order to protect freshwater aquatic life in NH, the state has adopted acute and chronic chloride criteria of 860 and 230 mg/L respectively. The chloride content in NH lakes is naturally low, generally less than 2 mg/L in surface waters located in remote areas away from habitation. Higher values are generally associated with salted highways and, to a lesser extent, with septic inputs." *

mg/L = milligrams per liter 

*Source: DES VLAP Chemical Parameter Explanations  

"Definition: VLAP uses the measure of chlorophyll-a, a pigment found in plants, as an indicator of the alga abundance. Because algae is a plant and contains chlorophyll-a, the concentration of chlorophyll-a found in the water gives us an estimation of the concentration of algae." *

mg/m3 = milligrams per meter cubed

*Source: DES VLAP Chemical Parameter Explanations