Fumee Lake Natural Area

Limnological Testing   Other results

Alkalinity    Hardness     pH     Chloride     Dissolved Oxygen       Conductivity 

Alkalinity
Alkalinity is the ability of water to neutralize acids. It is generally caused by the presence of carbonates, bicarbonates and hydroxides produced by rock -  limestone, for example - being weathered by water.  Alkalinity is expressed as milligrams per liter calcium carbonate; low alkalinity water has less than 75 mg/liter, high alkalinity water has more than 150 mg/liter.

Hardness
Hardness is a measure of calcium and magnesium ions. Hardness measures are often similar to alkalinity. Hard water lakes are usually more productive than soft water lakes. Hardness is expressed as mg/liter calcium carbonate with soft water ranging from 0 - 75 mg/liter and hard water from 150 - 300 mg/liter.

pH
The concentrations of hydrogen ions in water is expressed as pH. The pH scale ranges from 0 (very acidic) to 14 (very alkaline) with 7 being neutral. Most aquatic plants can tolerate a reasonable pH range but they function best when the pH is around 7.

Chloride
Chlorides usually occur in low concentrations in natural lakes, but excessive pollution may  increase in chloride presence. Chlorides are not harmful, but are often associated with pollutants and therefore are a general indicator of contamination from human activities.


Alkalinity, Hardness, Chloride and pH
for Fumee and Little Fumee Lake in early August 1994
Station
Location
Alkalinity
mg CaCO3/L
Hardness
mg CaCO3/L
pH Chloride
mg Cl/L
Fumee Lake
Surface
Mid-Depth
Bottom
124
128
136
152
152
150
8.34
8.39
8.52
11.0
3.3
5.5
Little Fumee Lake
Surface
Mid-Depth
Bottom
134
137
154
156
160
184
8.5
8.05
7.92
3.5
3.0
1.5

Dissolved Oxygen
An ample supply of dissolved oxygen (DO) is one of the most important components necessary for a normal aquatic community. Warmer water has less dissolved oxygen due to the fact that oxygen solubility decreases as water temperature increases. The stratification of a lake is important to the level of dissolved oxygen .
A dissolved oxygen concentration of 6.0 mg/L is sufficient for all species of fish that would live in both Fumee lakes. Concentrations below 2.0 mg/L would probably result in stress or discomfort in most fish species and few fish would be found in such locations for any length of time. Fumee lake had a DO concentration of 10.45 mg/L at the top and 8.6 mg/L at the bottom. In Little Fumee Lake the DO at the top was 9.15 mg/L and remained high throughout the surface layer. After 5 meters the DO began to rapidly decrease; at 6 meters the DO was 5.75 mg/L and at 7 meters that dropped to 0.8 mg/L.
The reason for decreased levels of oxygen near the bottom is the respiration of bacteria and phytoplankton. Generally the more nutrients in a lake, the greater the oxygen depletion. Little Fumee Lake appears to be a fairly productive body of water.

Conductivity
Conductivity is a general indicator of productivity. It is the ability of the water to conduct an electrical current. A high conductivity indicates significant amounts of dissolved substances in the water. Conductivity is reported in units of microhos per centimeter of water at 25o due to the influence of temperature on conductivity. This is called specific conductance or specific conductivity.
The specific conductance in the surface waters of Fumee Lake was 272 microhos/cm, and 265 microhos/cm for Little Fumee Lake. These values are typical for lakes having relatively hard water.