SCLIA conducts periodic water tests between the months of April/May through September/October.
pH
The pH of a lake should generally fall between 6.0 and 9.0. Different types of fish tolerate different pH levels but, in general, most fish will do better in water with a pH near 7.0. Lakes with a pH less than 6.0 may result in stunted, reduced or even absent fish populations.
pH is a determined value based on a defined scale, similar to temperature. It is a figure between 0 and 14 defining how acidic or basic a body of water is along a logarithmic scale. The lower the number, the more acidic the water is. The higher the number, the more basic it is. A pH of 7 is considered neutral.
Phosphorus
A level of 1 PPM of phosphorus would be considered excellent, at 4 PPM phosphorus levels are just fair. We would like to see levels consistently below 4 PPM.
Phosphorus is a component of organic materials such as leaves and grass clippings, pet waste, fertilizers and eroded soil. All water bodies receive phosphorus from the atmosphere and natural decomposition of aquatic plants, but problems “bloom” when they receive excessive deposits of nutrients from other sources.
Phosphorus damages lakes by feeding the growth of excessive algae. One pound of phosphorus can create 500 pounds of algae. Large algae blooms reduce lake clarity and impede the growth of other aquatic plants, and can deplete oxygen levels and harm fish. This process is called eutrophication. Algae blooms are also just plain unpleasant for swimming and boating.
Nitrates
Unlike temperature and dissolved oxygen, the presence of normal levels of nitrates usually does not have a direct effect on aquatic insects or fish. However, excess levels of nitrates in water can create conditions that make it difficult for aquatic insects or fish to survive.
Algae and other plants use nitrates as a source of food. If algae have an unlimited source of nitrates, their growth is unchecked.
A lake that has the milky color of pea soup is showing the result of high concentrations of algae. Large amounts of algae can cause extreme fluctuations in dissolved oxygen. Photosynthesis by algae and other plants can generate oxygen during the day. However, at night, dissolved oxygen may decrease to very low levels as a result of large numbers of oxygen consuming bacteria feeding on dead or decaying algae and other plants.
Nitrogen and phosphorus are nutrients that may cause increased growth of aquatic plants and algae. Nitrate-nitrogen concentrations above 3 PPM and any detectable amounts of total phosphorus may be indicative of pollution from fertilizers, manures or other nutrient-rich wastes.
Dissolved Oxygen
Dissolved oxygen (DO) is a measure of how much oxygen is dissolved in the water – the amount of oxygen available to living aquatic organisms. The amount of dissolved oxygen in a lake can tell us a lot about its water quality. Healthy water should generally have dissolved oxygen concentrations above 6.5-8 PPM.
Bacteria in water can consume oxygen as organic matter decays. Thus, excess organic material in our lake can cause eutrophic conditions, which is an oxygen-deficient situation that can cause a water body to “die.” Aquatic life can have a hard time in stagnant water that has a lot of rotting, organic material in it, especially in summer (the concentration of dissolved oxygen is inversely related to water temperature), when dissolved-oxygen levels are at a seasonal low. Water near the surface of the lake is too warm for them, while water near the bottom has too little oxygen. Conditions may become especially serious during a period of hot, calm weather, resulting in the loss of many fish.
Cold water can hold more dissolved oxygen than warm water. In winter and early spring, when the water temperature is low, the dissolved oxygen concentration is high. In summer and fall, when the water temperature is high, the dissolved-oxygen concentration is often lower.