8.0.2 Graph Types

From the water quality tests, the data is compiled into various charts and graphs. These are used to interpret trends or support a hypothesis. Each chart or graph can illustrate a unique aspect about the waters quality. Even if that aspect shows that the water quality is normal, unchanging, or average. All the values are compared chronologically with their sampled dates.

Chlorophyll A

Chlorophyll A concentration is related to total phosphorus. Look for the relationship between P and ChlA. Generally an increase in P means an increases in ChlA. The level of ChlA is compared to other lakes and is used to diagnose the trophic state of the water. The higher the concentration of ChlA in the water, the greener, or less transparent it becomes.

Chlorophyll A loading relates the amount of algae being dumped into the lake. Given sufficient nutrients the algae will continue to grow. A certain amount of algae entering the lake through streams is normal. If too much algae is entering the result can be rapid eutrophication of the lake.

Fecal Colonies

Fecal colonies concentration represents a health hazard. Fecal matter is also a P source. Look for values that spike during storm events. A concentration of over 200 FC/100ml is considered a health hazard.

Fecal colonies loading relates to severity. A source can be diluted by large amount of water volume. Loading gives a more accurate relation to the severity of the source.

Total Suspended Solids

TSS concentration relates to clarity as well as P. The higher the concentration of TSS the cloudier the water appears. Also P can be bonded with TSS.

TSS loading can relate to sediment. Heavy TSS loading can lead to build up. This build up can cause the stream to be redirected, or if the sediment is nutrient rich can cause new aquatic plant growth and eutrophication.

Total Phosphorus

TP concentration is directly related to the eutrophication of the water.

TP loading directly relates to the nutrient impact to the lake. The more P entering the lake the more eutrophic the lake will become.

Flow

Flow loading is observed to see seasonal trends. Events such as high precipitation and spring runoff can be observed. Also trends can be identified to see if flow is increasing or decreasing. This could relate to interference from man such as irrigation or damming.

Precipitation

Graphs that correspond with precipitation charts can show if a relationship exist between loading, concentrations, and rainfall.

General Statistics

General statistics are an average indicator. Usually data is averaged over the entire sampling lifetime. Missing values are excluded. Special samples like storm events are also included. By including storm events in the statistics the data is balances towards a more accurate average since not every storm event is monitored. General statistics can also identify important correlations between land areas, land use, loading, concentrations, weather, and more. All of which help organize the data so that anomalies are identified.

Next page: Totals and Average Loading by Watershed