This calculator determines the maximum harvestable right dam capacity for a landholding.

The combined volume of all dams (or parts thereof) on a landholding that capture and store harvestable rights water cannot exceed the maximum harvestable rights dam capacity.

For landholdings located in coastal-draining catchments and central-inland draining catchments of NSW, the calculator determines a dam capacity based on 10% of the average annual regional rainfall runoff from a landholding.

For landholdings located in the Western Division of NSW, the calculator determines a dam capacity based on 100% of rainfall runoff from a landholding.

For details about the limits applying to areas of NSW and for more information on harvestable rights, visit the Department of Climate Change, Energy, the Environment and Water's website.

Landholding details

1. Find your landholding

Click and drag the marker marker to approximately the middle of your landholding.

Your 'landholding' can be one or more lots that are adjoining or would be adjoining if not separated by a road or watercourse.

2. Calculate total landholding area

Enter the total size of your landholding. Make sure you select the correct units for the size of your landholding.


Location of dams

The maximum harvestable right dam capacity calculator does not verify that the location of the proposed dam is lawful. It is up to the landholder to ensure the proposed dam site complies with the location requirements set out in the harvestable rights order.

Information on determining stream order and where dams can be built can be found in the Harvestable rights dams - where can they be built? fact sheet and in the department’s website frequently asked questions.

Harvestable rights dams cannot be constructed on or within three kilometres upstream of a Ramsar wetland site, listed at the time of construction or first use of the dam. There are currently 12 Ramsar wetlands in NSW.

Overall dam capacity on a landholding

The calculator determines the combined maximum dam capacity for all potential harvestable rights dams on a landholding.

The calculator does not take into account the capacity of existing dams on your landholding. If you have existing harvestable rights dams on your landholding, you must take the capacity of these dams into account when constructing new dams or enlarging existing dams, up to the calculated maximum dam capacity for your landholding. See the department's frequently asked questions for further information.

Maximum dam capacity in the coastal-draining catchments

Please note that the harvestable rights limit for coastal-draining catchments was returned to 10% of rainfall runoff in September 2023 (from the previous 30% limit that commenced in May 2022).

The calculator has been updated to reflect this.

For more information on this change, visit the Department's website.

Default 1 megalitre dams on small landholdings

If a landholding resulted from a subdivision approved by a relevant planning authority (for example, local council) before 1 January 1999 and the maximum dam capacity for the landholding is less than 1 megalitre, the maximum dam capacity for that landholding is taken to be 1 megalitre.

No further harvestable right dams can be constructed on the landholding and any new dams above 1 megalitre must be licensed.