The Vasse Wonnerup wetlands are of great ecological value with seagrass meadows, native fish populations and large numbers of waterbirds. Yet the wetlands also struggle with poor water quality. Excessive nutrients flowing into the wetlands from the catch-ment can fuel blooms of phytoplankton and macroalgae. As well as being a nuisance and discolouring the water these blooms can be toxic, and as they die and decompose oxygen can be stripped from the water, potentially leading to fish kills and creating areas that cannot support a healthy aquatic ecosystem.
The water quality index aims to track the changes in concentration of nutrients in the wetlands as well as the concentration of phyto-plankton growing in the water. The index has been developed specifically for the Vasse Wonnerup wetlands as it is a unique system with significant modifications including surge barriers on both estuaries and a seasonally opened sand bar at its mouth.
Routine monitoring data collected at least monthly from across the wetlands by the Department of Water and Environmental Regula-tion is used to calculate the index in each year for both the wet (May – October) and dry (November – December) seasons. The index was develop by DWER (with the methodology report in development) using the following parameters:
Spring | Upper Vasse | Lower Vasse | Vasse Channel | Wonnerup Inlet | Lower Wonnerup | Upper Wonnerup | Download Reports |
---|---|---|---|---|---|---|---|
2023 | B | D | D | A | B | B | Download Report |
2022 | C | D | C | A | B | C | |
2021 | D | D | E | A | B | B | |
2020 | D | D | D | B | C | D | |
2019 | C | D | E | B | D | C | |
2018 | B | D | E | D | D | D | |
2017 | B | C | C | B | A | B |
Year | Upper Vasse | Lower Vasse | Vasse Channel | Wonnerup Inlet | Lower Wonnerup | Upper Wonnerup | Download Reports |
---|---|---|---|---|---|---|---|
2023 | B | B | A | A | A | B | Download Report |
2022 | E | C | A | A | B | D | |
2021 | C | C | B | A | B | E | |
2020 | C | B | A | A | C | D | |
2019 | A | B | A | A | C | E | |
2018 | C | C | A | A | C | B | |
2017 | B | B | A | A | E | D |
A
Excellent
B
Very Good
C
Fair
D
Poor
E
Very Poor