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.
| 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.
