Making Sense of Water Quality Data
Comparing two points on the Suwannee River
Background:
The Suwannee River is a federally designated wild river, which means that it cannot be dammed and that there are protections in place to prevent other kinds of development along the river. This means that the Suwannee has continued to flow unobstructed from its headwaters in the Okefenokee Swamp, through the Florida Panhandle and into the Gulf of Mexico. It is one of only 1% of American rivers designated under this protection, flowing wild in the same way since it first cut through the region’s limestone rock deposits in prehistoric times. Labeled as a Blackwater river, the Suwannee moves at a slow pace and has low dissolved solids and conductivity. Blackwater rivers like the Suwanee often appear dark in color and can be acidic due to the tannins which are the byproduct of decaying plant materials.
Although its federal designation as wild river is meant to preserve the river and prevent it from being changed by human activity, one of the defining features of any river is change. Its waters rise and fall with rain. Erosion can change the banks over years, but can even alter day to day. Even the path of the river itself can meander from side to side over time. It should come as no surprise then that the characteristics of the water in the river are not constant, but can and do change hour to hour, day to day, and across seasons. In fact, the parameters that we use to measure water quality, such as dissolved oxygen, pH, turbidity, and temperature can vary across time and between locations within the same river.
In this activity, you’ll be looking at the data for the Suwannee River from two different locations just 80 miles apart from each other. One location, Dowling Park, is just downstream from the Twin Rivers Wildlife Management Area, inland on the Florida Panhandle. The other location, West Pass, is in the lower Suwannee River at the point just before the river flows into the Gulf of Mexico. We have included data from both locations from 2019 to 2024 in this dataset. Explore the different measured water parameters and find out which are most similar in both locations and which are most different.
Dataset
This dataset was sourced from the Suwannee River Water Management District's online interactive map. Data from the Dowling Park Bridge and West Pass above Split locations were compiled with data included for one winter and one summer observation each year. Each row in the dataset is one observation at one location.
You find find these data as well as data for other locations at: http://www.mysuwanneeriver.org/portal/waterquality.htm
Note that these data were categorized as “surfacewater-Active” data in the search of the online interactive map.
Variables
Location - This categorical variable identifies the location of water sampling. The two values in the dataset are Dowling Park (inland on the Florida Panhandle) and West Pass (near where the river meets the Gulf of Mexico).
Date - This info variable lists the month and year the data were recorded. Listed as month/year. This is not a graphable variable.
Months since Jan 2019 - This numeric variable counts the amount of months since January 2019. This numeric variable was created based on the value of Date to be used in graphing. It is a way of showing time on a graph.
Water Temp. (°C) - This numeric variable measures the temperature of the water. Measured in degrees Celsius.
Visibility (m) - This numeric variable indicates the depth at which a Secchi disk is no longer visible, indicating the transparency of the water. A Secchi disk has an alternating black and white pattern and is lowered into the water on a string. Visibility is measured in meters.
Salinity (ppt) - This numeric variable measures the dissolved salt concentration in the water. Measured in parts per thousand.
DO (mg/L) - This numeric variable indicates the amount of dissolved oxygen in the water sample. Measured in milligrams per liter.
pH - This numeric variable measures the pH value of the water sample. pH measures the acidity or alkalinity of a substance, usually a liquid or chemical. The pH scale ranges from 0 to 14, with 7 being neutral.
Activity
Part 1: Compare water temperature and dissolved oxygen
1. Make a graph showing water temperature over time at the two locations. Show Water Temp. (°C) on the y-axis and Months since Jan 2019 on the x-axis. Add Location as the z-variable (color code) and Connect dots with lines. Paste your graph below:
2. Describe the pattern that you see for water temperature at the two locations over the time period of 2019 to 2024.
3. What appears to be driving the fluctuation up and down that you see in the data? Hint: you can hover your pointer on any of the dots to see some information about a specific data point.
4. In which location is the river warmer? Refer to your graph as evidence.
5. Now make a graph showing dissolved oxygen over time at the two locations. Show DO (mg/L) on the y-axis and Months since Jan 2019 on the x-axis. Add Location as the z-variable (color code) and Connect dots with lines. Paste your graph below:
6. How is this pattern in the data the same as you saw for water temperature and how is it different?
7. Make a new graph showing DO (mg/L) on the y-axis and Water Temp. (°C) on the X-axis. Uncheck the box for Connect dots with lines and check the box for Regression line to add a line of best fit. Paste your graph below:
8. Referring to the graph that you just made above as evidence, what is the relationship between water temperature and dissolved oxygen?
Part 2: Compare visibility and salinity
9. Make a graph showing visibility over time at the two locations. Show Visibility (m) on the y-axis and Months since Jan 2019 on the x-axis. Add Location as the z-variable (color code) and Connect dots with lines. Paste your graph below:
10. Describe the pattern you see in the data. In which location is the water in the Suwannee more clear? Refer to your graph as evidence.
11. Make a graph showing salinity over time at the two locations. Show Salinity (ppt) on the y-axis and Months since Jan 2019 on the x-axis. Add Location as the z-variable (color code) and Connect dots with lines. Paste your graph below:
12. Describe the pattern you see in the data? In which location is the salinity higher?
13. What might explain the large fluctuations in salinity that were recorded at the Dowling Park location?
Part 3: Compare pH
14. Make a graph showing pH over time at the two locations. Show pH on the y-axis and Months since Jan 2019 on the x-axis. Add Location as the z-variable (color code) and Connect dots with lines. Paste your graph below:
15. The typical range in pH for a North American river is 6.5-8.2. What range in pH values do you see in the data for pH across both locations? How do you think this is related to the characteristics of a blackwater river like the Suwannee?