Urban Wetland Invasive Species Removal Program

Invasive water plants, such as Water Hyacinth (Eichhornia crassipes) and Salvinia (Salvinia molesta), pose a significant threat to the delicate ecological balance of Colombo’s urban wetland ecosystems and waterways. These non-native species can rapidly out-compete native plants, disrupt habitats, and negatively affect biodiversity. To ensure the health and resilience of wetlands, it is essential to implement effective strategies to clean and manage invasive water plants.

Water hyacinth (Eichhornia crassipes) is a free-floating flowering aquatic plant is one of the most invasive weeds introduced for ornamental purposes in Sri Lanka. It is native to the Amazon Basin in South America and was introduced as an ornamental plant in 1904. It is widely distributed throughout the island despite its declaration as a prohibited weed under the Water Hyacinth Act in 1909, and subsequently under the Plant Protection Act in 1924. 

Salvinia molesta is an exotic plant that was introduced into the country for experimental purposes in the 1940s. It is a surface plant that rapidly invades large areas of aquatic habitats and was declared a noxious weed by the Plant Protection Act in 1952.  

The Gothatuwa Wetland Park utilises two methods of invasive plant removal:

  1. Mechanical Removal: For larger-scale infestations, mechanical methods such as dredging or cutting machinery can be employed. These methods are effective for clearing large areas, but require careful planning to minimise habitat disturbance.
  2. Manual Removal: Manual removal is often the primary method used for small infestations or delicate wetland environments. Trained personnel, volunteers, or conservation groups can physically uproot or cut invasive plants at the root or stem level. Proper disposal is essential to prevent reintroduction, and all removed plant material should be collected and disposed responsibly.

With the sheer number of invasive plants that are currently choking up wetland waterways, we are in need of volunteers to help park staff manually remove water hyacinth. By engaging the public in wetland conservation efforts such as this, we hope to foster a sense of responsibility and ownership in preserving these vital habitats. 

Urban Fishing Cat Team cleaning up hyacinth at the Diyasaru Park. Video by Tashiya De Mel.

If you are interested in volunteering, here’s what you need to know.


Gothatuwa Wetland Park

Clean-up days:

Invasive species removal in September will be conducted on Saturdays and Sundays.

Saturday sessions:

7:00am: Meet at Gothatuwa Wetland Park entrance.

7:15am: 15 minute introduction and safety briefing. 

7:30am: Cleanup begins.

11:30am: Clean up ends.


Due to a limited number of equipment, we can only host 10 volunteers per session. 


Important information:

You will be required to bring the following items:

  • Water (lots)
  • Snacks (please note that any plastic items must be taken home with you)
  • Gloves

You are required to wear:

  • Closed-toed shoes
  • Long pants / jeans (please note that you will get dirty)
  • Hat / cap
  • Sunglasses (if you are prone to headaches or migraines)

Participants under the age of 18, must be accompanied by a parent or guardian.

Are you ready to battle the invasives?