Pollution Index Chart

A pollution index chart is used to determine the quality of water. To use one, count the number of a certain algae then divide by 5. If the number of algae in the sample is below before dividing, then just ignore it. Continuing, always round down when dividing. Even if the number is 4.9, it would be 4. Next, take that number and multiply it by the number in the column of the corresponding algae. Once finished, add all the algae numbers together. If the number is 20 or greater, the pollution is high, if the number is between 15-19, the level is probable, and if the number is 14 or less, the pollution is low. The benefits of using a pollution index chart include knowing what algae is in the water and what condition the water is in. However, the drawback is that it's only a pollution index for a small sample of the entire body of water so the results could be deceiving. If the population of certain algae is high but the diversity is low, the water is polluted, possibly as a result of organic pollutants. When the diversity of algae is high but the population is low, the water is cleaner and healthier.