A Closer Look: State of the Elizabeth River
An update on the health of the Elizabeth River
To measure the health of each river, scientists took samples throughout the watershed from 2015-2019.
11 parameters were measured. Each one helps tell the story of what is happening in the ecosystem.
1) Dissolved Oxygen
Dissolved oxygen is crucial for fish and other aquatic life. Samples were compared to the open water state threshold of 5mg/L.
2) Nitrogen
An important nutrients for algae growth but in excess can lead to algal blooms and fish kills.
The amount was compared to EcoCheck thresholds.
Overfertilization is one cause.
3) Phosphorus
An important nutrients for algae growth but in excess can lead to algal blooms and fish kills.
The amount was compared to EcoCheck thresholds.
Overfertilization is one cause
4) Phytoplankton/ chlorophyll
Algae, known as phytoplankton, are vital for a productive river.
But some types of algae are harmful and in excess can lead to poor water quality.
Compared to EcoCheck thresholds.
5) Water Clarity:
Measures the depth that sunlight penetrates through the water column.
Important for aquatic vegetation growth and in turn fish and other organisms.
6) Bacteria (recreation criteria):
Enterococcus bacteria is an indicator of animal and human waste.
Elevated levels pose a risk to human health. Values were compared to state criteria for recreational human contact (104 colony forming units)
7) Bacteria (shellfish criteria):
Fecal coliform bacteria levels in river water, associated with animal and human waste, compared to state criteria for shellfish harvest.
8) PAHs in sediment:
Polycyclic aromatic hydrocarbons (PAH) are correlated with cancer in fish and are often a legacy toxin associated with wood preservation and burning fossil fuels
9) Cancer in Fish:
Prevalence of both precancerous and cancerous lesions found on the liver of the small non migratory fish, the mummichog .
10) Bottom Health:
Abundance and diversity of life on the river bottom (worms, clams etc.)—indicates food availability for many fish.
11) TBT
Concentrations of Tributyltin (TBT) detected in the water column.
A highly highly toxic substance to marine organisms even a very low concentrations.
After compiling the data from 2015-2019 letter grades were assigned to each stream by averaging the parameters grades.
Letter grades associated with each parameter throughout the Elizabeth River.
By averaging all parameter grades we can compare the overall letter grade for each stream
Click the buttons to compareletter grades by stream for each parameter
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No Trends
Water Clarity- No trends
Recreational Bacteria- No trends
Degrading Trends
Shellfish Bacteria Standards- Degrading conditions (increasing levels of bacteria in M, L, W)
Improving Trends
Nitrogen-
Broad Creek and Indian River Improving
Phosphorus-
Paradise Creek Possibly Improving
Chlorophyll-a-
Southern Branch Possibly Improving
Dissolved Oxygen-
Western Branch Possibly Improving
Are the streams in the Elizabeth River watershed improving?
Move the slider to compare this report card 2015-2019 to the previous report card 2014-2018
From the last report card Southern Branch, Eastern Branch and Paradise Creek improved from D to C. road Creek, and Indian River improved from F to D and C respectively. The mainstem improved from C to B while Lafayette River and Western Branch remain at C.
Broad Creek, and Indian River improved from F to D and C respectively. The mainstem improved from C to B while Lafayette River and Western Branch remain at C.
