Water Chemistry Lab Tests


Alkalinity  – The result of this test indicates the water’s buffering capacity. Water with adequate buffering capacity can limit dangerous pH swings caused by the introduction of highly acidic substances, such as acid rain and pollution, the effects of which can be compounded by the subsequent loss of plant, algal, and other aquatic life.

Ammonia – Ammonia can be toxic to fish and other animals. The level of toxicity, however, is based on the total ammonia concentration, pH, and temperature. Higher levels usually mean that the pond is being exposed to unusual discharges, while lower levels help limit plant and algae growth. Multiple management strategies are available to control ammonia levels.

Chloride /Salinity – The Chloride ion is one of the major inorganic anions in water and wastewater. Although chloride is essential to plants in very low amounts, it can cause toxicity to sensitive crops at high concentrations. Water with high salinity is toxic to plants and may become hazardous to the ecosystem. High levels of Chloride or Salinity may be caused by the proximity of the lake to the ocean or low water levels which cause salts to become more concentrated within the water body.

Color – The measured value for color reflects decomposition of organic matter in the lake. This organic matter may be the result of decaying plankton and aquatic plants or other inputs from the surrounding watershed .

Sam testing a lake sample

Conductivity and total dissolved solids (TDS) – These measurements estimate the total concentration of ionized substances dissolved in the water. The inorganic anions dissolved in water include carbonates, chlorides, sulfates and nitrates, while inorganic cations include sodium, potassium, calcium and magnesium.

Lake water TDS and conductivity levels vary naturally based on the specific characteristics of the lake (e.g. geology, proximity to the sea, etc). A significant and acute increase in conductivity may indicate a recent increase in domestic or industrial pollution. High dissolved solids may cause irrigation water to stain vehicles and other surfaces in the general vicinity.

Hardness / Alkalinity  – Alkalinity indicates the water’s capacity to resist changes in pH. Good buffering capacity can limit dangerous pH swings caused by the introduction of highly acidic or basic substances. Total hardness is defined as the concentration of calcium and magnesium in the water. Calcium is necessary for proper fish egg and fly development.

Iron  – When concentrations exceed 0.1 mg/L, iron precipitates on exposure to air, decreasing pond clarity, potentially clogging irrigation pipes, and encouraging iron bacteria, this affects the flavor of fish and water. Levels greater than 0.3 mg/L can cause staining on buildings and sidewalks when the water is used for irrigation.

pH – The pH value of a body of water expresses its tendency to donate or accept hydrogen ions on a scale of 0 (very acidic) to 14 (very basic). Natural waters generally range from pH 6.5 to pH 8.5 but can vary. Water with long-term low or high pH readings can be corrosive, causing potential problems with irrigation equipment or structures. Aquatic animals are greatly affected by changes in pH.

Phosphate – Total phosphorus (TP) refers to all the various forms of phosphorus in the water, while phosphate (PO43-) refers specifically to the dissolved form of phosphorus in the water column. Phosphate is the most biologically active form of phosphorus. Phosphate levels are expected to range from 0.01 to 0.05 mg/L for healthy freshwater systems.

Total Phosphorus – Phosphorus is a naturally occurring component of aquatic systems and it is necessary for a balanced ecosystem. Elevated levels of phosphorus, however, can cause shifts in this balance and is the most common cause of the undesirable growth of aquatic weeds and algae. The discharge of treated wastewater and agricultural drainage into a lake will increase a lake’s phosphorus levels. Lawn and landscape fertilizer runoff is another major source of phosphorus in lakes and their use should be avoided near the water. In such cases, multiple management strategies may be required to lower phosphorus levels.

Turbidity  – Lack of clarity, known as turbidity, in natural waters is caused by the presence of suspended solids such as silt, clay, fine organic and inorganic matter, plankton and other microscopic organisms. The turbidity test measures an optical property of the water sample and is used as an index of water clarity. Elevated turbidity levels are often due to increased runoff, higher flow, or construction activity in the drainage basin. The degree to which turbidity affects wildlife depends on both the level of turbidity and the duration of exposure. Low turbidity levels can begin to stress fish within a few hours.

Patrick and Caitlin work on samples

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