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What is Alkalinity?
It is the measure of the capacity of water to neutralize acids or hydrogen ions. Alkalinity is sometimes referred to as "carbonate hardness".

What factors influence the amount of alkalinity in your watershed?
1. Alkalinity may be due to the presence of the bicarbonate ion, which is derived from the dissolution of carbonates by carbonic acids.
2. Minor contributors to alkalinity include carbonate and hydroxide ions.
3. Some sources of alkalinity are leached from limestone and soil.
4. Some minerals such as dolomite and calcite provide a source of alkalinity.
5. Low alkalinity may be due to high levels of precipitation in the form of rain or snow.

What is the optimal amount of alkalinity in a watershed?
1. An alkalinity range of 100-250 mg/L for a river is considered normal and will stabilize the pH of the river.
2. Levels between 20-200 mg/L are typically found in freshwater.
3. Seawater typically has levels between 100-125 mg/L.

What factors are affected by the amount of alkalinity in a watershed?
1. Alkalinity may work to buffer the water against sudden changes in pH and consequently protect aquatic organisms from sudden changes in pH.
2. If alkalinity of water is too high, the water can be cloudy, which inhibits the growth of underwater plants.
3. If alkalinity is too high, it raises the pH level, which in turn harms or kills fish and other aquatic organisms.
4. Low alkalinity may cause the pH of water to be very acidic and can negatively affect hatching and development of aquatic animals and adult fish.


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