Managing ICOLLs


Byron Shire has two Intermittently Closed and Open Lakes and Lagoons (ICOLLs): Tallow Creek and Belongil Creek. 

As the Byron Shire has developed and the population has grown, housing has built-up along the coast and within the Belongil Creek and Tallow Creek catchments. The change in weather patterns in recent times and natural processes of these intermittently closed and open lakes or lagoons (ICOLLs) can be at odds with these nearby built environments. 

When the mouths of creeks build up with sand (creating a sand berm), water cannot escape and can cause flooding of yards, properties and public infrastructure. The water build up can also create poorer water quality in the creek and lead to odours.

Why is creek management necessary?

At times, the entrances to Belongil Creek and Tallow Creek need to be artificially managed.  What this means and what it may involve include:

  • scraping the sand bar (beach berm) to promote natural opening of the creek mouth to the ocean;
  • artificially (also referred to as mechanically) opening the creek mouth to the ocean by digging a small channel to allow the water to escape, or flow, to the ocean.

Council manages the entrances to Belongil Creek and Tallow Creek ICOLLs in accordance with licences from:

  • National Parks and Wildlife Service (NPWS)
  • Department of Primary Industries (DPI) - Fisheries
  • Marine Park Authority
  • Crown Lands

In general, creek entrance management is necessary when water levels are high to decrease risk of flooding in the catchments.   

Collaboration with public authorities and other key stakeholders including Arakwal and environmental groups is important to ensure the values of these creek systems are protected.

Having a flexible and adaptable 'best practice' ICOLL opening strategy is important to minimise the risks of fish kills. 

Opening ICOLLs - it's a delicate balance

Belongil Creek and Tallow Creek ICOLLs are natural coastal lagoons.  A delicate balance is necessary to seek an opening and closing regime of the creeks as close as possible to natural.

When creeks have been closed for a long time and water inundates backyards and access to walkways are cut, it is understandable that this can be concerning and upsetting and prompts people to call for the sand at the mouth of the creek to be artificially removed.

Meanwhile, other people support natural ICOLL fluctuations and do not want artificial openings to occur at the creek mouth.

Unfortunately, both artificial openings and natural openings sometimes result in fish kills. 

What triggers the opening of an ICOLL? 

Belongil Creek 

Belongil Creek has permission from the NSW Government (Crown Lands and DPI Fisheries - Marine Parks) to artificially open the mouth of the creek in accordance with Council's entrance opening strategy. The most recently finalised strategy provides flexibility and adaptability.

The first condition that must be met in order for Council to initiate an opening is for the water in Belongil Creek to reach the 'watch level' of 1.0 metres AHD (above sea level).

Tallow Creek

Council has permission from NPWS and DPI Fisheries - Marine Parks to manage the entrance of Tallow Creek in accordance with a revised 'Interim Position' of the existing Environmental Management Plan and Opening Strategy. The revised Interim Position was created in response to the most recent fish kill event in June 2019 and does not support mechanical opening of the creek. Council has permission to undertake the following management activities with agreement from agencies:

  • Scrape the beach berm when it reaches 2.2 metres AHD (above sea level); and
  • A rain event has or is due to commence.

Council will now manage the entrance of Tallow Creek by encouraging 'natural breakout' events of the creek. By lowering the beach berm (using an excavator) to allow overtopping during a rainfall event a more natural ICOLL opening event is mimicked, decreasing the potential for a fish kill.

ICOLL best practice management

Best practice management strategies are in place for Belongil Creek and Tallow Creek in the Byron Shire. 

The Tallow Creek and Belongil Creek ICOLLs are complex estuarine environments that play an important role in the estuarine and marine ecosystems and the best manager of these systems is nature.

A huge range of complex, scientific factors and issues are assessed before an ICOLL is artificially opened.  It is important for people to understand that the following list of issues or conditions DO NOT meet the requirements for an ICOLL opening:

  • Low water levels
  • In dry weather
  • Water quality
  • Odour
  • Public amenity

Read more about the Environmental Management Plan and Opening Strategy in place for Tallow Creek ICOLL and Belongil Creek ICOLL.

ICOLL Monitoring

We have an on-going environmental monitoring program for Tallow and Belongil Creeks.

This includes:

  • water quality data from equipment located in the creek systems.
  • monthly water samples.
  • sampling and assessments for any artificial openings of the creeks.
  • monitoring of vegetation adjoining the estuaries.

The reports contain complex, technical information and the large file size makes downloading difficult.

Please contact the Coastal Team if you would like a copy of any of these reports or to talk about our environmental monitoring programs:

Chloe Dowsett