Water Quality Indicators VA Grade 6 2023

Seven indicators of water quality are the amount of disolved oxygen, nitrates, pH, and phosphates​, temperature, turbidity, and eutrophication

​Seven water quality indicators

Water is the universal solvent. Oxygen gas can be dissolved in water.

Most organisms need at least 5-6 ppm (parts per million) to survive.

Dissolved oxygen is affected by temperature, the amount of decaying organic material in water, and stream flow.

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​Dissolved oxygen

Nitrates are a primary plant nutrient but very little is needed. Too many nitrates cause algae blooms that reduce water quality. An algal bloom is the rapid spread of algae.

Levels must stay below 1 g/mL for normal plant growth.

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​Nitrates

High levels of nitrates are an indication of poor water quality.

The level of nitrates is affected by agricultural runoff, animal feedlots, and industrial wastewater.

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​Nitrates

pH is a measure of how acidic or basic a substance is. Most organisms exist within a pH range of 5.5 to 9.5.

pH is affected by acid rainfall, algal blooms, and industrial processes that allow runoff.

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pH

Phosphates are plant nutrients but only a very small amount is needed. Excess phosphates cause algal blooms.

Acceptable levels must stay below 0.1 m/gL. High levels are an indication of poor water quality.​

Phosphates

The amount of phosphates is affected by agricultural runoff, urban runoff, animal feedlots, and industrial wastewater.

Phosphates

Most aquatic organisms live within a range of 32-90^o F. Rapid change and extremes can stress aquatic organisms.

Temperature is affected by air temperature, amount of shade and the amount of soil erosion.

Remember that animals can survive under water because frozen water floats to the top and the animals go under the ice.

Temperature

Turbidity is how clear water is. A Secchi disc measures turbidity. It is affected by the amount of sediment in the water.

Turbidity

A natural process where water bodies receive excess nutrients (nitrates and phosphates) that stimulate excessive plant growth. It's caused by too many nutrients in the water.

Eutrophication