What is calcium and water hardness?
1. Water hardness is the state or quality of being hard caused by various dissolved salts of calcium, magnesium, or iron.
2. Calcium (Ca2+) is one of the major inorganic cations, or positive ions, in saltwater and freshwater. It originates from the dissociation of salts, such as calcium chloride or calcium sulfate, in water.

What factors influence the amount of calcium and water hardness in your watershed?
1. Various dissolved salts of calcium, magnesium, or iron in the river cause water hardness.
2. Calcium and magnesium enter the water mainly by leaching of rocks. Most calcium in surface waters come from streams flowing over limestone, dolomite, gypsum, and other calcium-containing rocks and minerals.

What is the optimal amount of calcium and water hardness in a watershed?
1. The range of water hardness can range from 0-100 grains per gallon.
2. 10 grains per gallon is considered very hard water.
3. Water with calcium levels of 10 mg/L or less are usually oligotrophic, and can support only sparse plant and animal life.
4. Calcium levels above 25 mg/L are typical of eutrophic waters.
5. Typical freshwater magnesium levels range from 5-50 mg/L.
6. Typical freshwater calcium levels range from 4-100 mg/L.
7. Typical seawater contains 400 mg/L of calcium.
8. Typical seawater contains 1350 mg/L of magnesium.

What factors are affected by the amount of calcium and water hardness in a watershed?
1. Hard water may precipitate carbonate mineral deposits, scale, and incrustations on pipes, hot water heaters, boilers, and cooking utensils.
2. Water hardness can cause other problems in homes such as increased soap consumption because it can prevents soap and other detergents from lathering.
3. Calcium is an important component of aquatic plant cell walls
4. Calcium is an important component in the shells and bones of aquatic animals.
5. Magnesium is an essential nutrient for plants, and it is a component of the chlorophyll molecule.
6. Water with low calcium levels are usually oligotrophic, and can support only sparse plant and animal life.
7. High calcium levels are typical of eutrophic waters.