Water Quality Analysis

The Lake Ecology and Water Quality Laboratory here at the Bella Vista Property Owners Association have gathered and analyzed water quality data for Bella Vista lakes and streams. The goal is to monitor and understand the health of Bella Vista waters. This data is useful for our biologists, but it is also important that it be accessible to members who are also interested in the health of our waters.

Understanding the Analysis

The goal is to monitor and understand the health of Bella Vista waters. Currently the analysis has 11 water quality parameters, listed below. The data for the analysis is collected for each lake and stream site every month.

  • Photic Depth
  • Secchi Depth
  • Turbidity
  • Chlorophyll
  • Conductivity
  • pH
  • Dissolved Nitrogen (Nitrate/Nitrite)
  • Total Nitrogen
  • Dissolved Phosphorus (Orthophosphate)
  • Total Phosphorus
  • E coli

Most of these water quality parameters focus on measuring things that affect plankton. There are two types of plankton: phytoplankton (tiny plants) and zooplankton (tiny animals). Plankton are a vital part of the food web, feeding larval fish and adults of some fish species, so it is important that we monitor them.

Photic depth and secchi depth both measure water clarity. Photic depth measures how deep light penetrates the water, while secchi depth is how deep humans can perceive an object. Photic depth is important because it defines where plankton can thrive. Like all plants, phytoplankton need access to sunlight so they can grow, thus they need to inhabit the photic zone, the bottom of which we measure as the photic depth. Zooplankton eat the phytoplankton and also inhabit the photic zone.  Secchi depth can then be used as a proxy for how well plankton are doing.

Turbidity and chlorophyll both help explain photic and secchi depths. Turbidity measures particles leading to cloudiness. Turbidity results from sediments and organic material like plankton. Chlorophyll is the photosynthetic pigment in algae and plants and measures the phytoplankton component of turbidity. The ideal scenario is that virtually all turbidity is explained by plankton.

Conductivity measures the dissolved ions, or charged particles, in water. These dissolved ions are things like salt. There needs to be ions in the water for the health of the plankton community, but it should not be excessively high.

The measurement for pH indicates how acidic or basic the water is: 0 is very acidic, 14 is very basic, and 7 is perfectly neutral. This scale is logarithmic, so each whole number on the scale is a factor of 10 stronger in acidity or basicity then the previous. For example, pH 4 is ten times more acidic than pH 5 and 100 times more acidic then pH 6, and pH 10 is ten times more basic than pH 9. Natural waters usually range from pH 6-9.

Nitrogen is important for growth in plants and animals. Dissolved nitrogen in freshwater comes mainly from nitrate, and to a smaller degree nitrite, and is readily absorbed by plankton. Total nitrogen includes dissolved nitrogen compounds as well as nitrogen bound to sediments and in organic material like plankton.

Phosphorus is important for growth in plants and animals. Dissolved phosphorus in freshwater comes almost entirely from orthophosphate and is readily absorbed by plankton. Total phosphorus includes dissolved phosphorus compounds as well as phosphorus bound to sediments and in organic material like plankton.

E. coli is a bacteria that is naturally present in the environment and inside animals. Humans have E. coli present in the lower sections of the gastrointestinal tract, but these bacteria can cause illness if large numbers are introduced to the upper sections, i.e. the mouth and stomach. The Arkansas Department of Health threshold for safety is 126 colony forming units (CFU) of E. coli per 100 mL.

Reading the Graphs

Individual parameters graphs for each lake

At the top of each graph is a title indicating which lake and parameter the graph is showing data for. The x-axis or bottom horizontal axis shows the years and months for which we have data. The y-axis or left-hand vertical axis shows the values of the data. For each parameter, the units will be indicated in the parentheses. For example, in the graph below for Lake Ann, photic depth is shown in meters (m).

Composite graphs for each parameter

For ease of comparison, for each parameter, all lakes were plotted on a single graph. These graphs are identical to the parameter graphs above but show all lakes. For example, the graph below shows photic depth for all lakes.

About The Author of this Study

Chris Fuller holding up a fishing net while standing in a boat on a lake

Chris Fuller, M.S.

Lake Ecology and Water Quality Sr. Tech

  • Joined in 2015; Native of Central Arkansas who moved to Bella Vista for work.
  • Ten years of experience as a researcher and aquatic biologist; holds B.S. and M.S. in Biology from University of Central Arkansas.
  • Started career as an aquatic insect technician during B.S.
  • Ongoing member of the American Fisheries Society and occasional member of the Society for Freshwater Science.