"Gravel" is defined as "granular material with particle sizes that varies between 2mm and 256mm". Protecting our river beds in this way helps to avoid habitat loss and/or deterioration in habitat quality.
Gravel provides a habitat for many aquatic species at different stages of their life cycle. Certain fish species including salmon, trout and lamprey excavate gravel to create what is referred to as a “redd”. This is where they deposit their eggs/ova. Gravel substratum has to be of a suitable quality (various sized gravels to ensure an adequate flow of oxygen to the eggs during incubation) for the successful development of eggs and emerging fry. These spawning gravels can be impacted by physical disturbance and input of sediments. Physical disturbance can destroy eggs and sediment can block spaces between the gravel particles reducing water flow through the redd, thereby limiting the dissolved oxygen available to the developing eggs.
River gravel is a highly mobile material that erodes and deposits naturally along the length of a rivers catchment. Removal of this gravel from rivers and streams can also negatively affect a river's hydro-morphology by destabilising the river bed, causing the river bed to drop. It can undermine river banks by altering the river channel, both at the point of removal and in neighbouring properties up and downstream. River bank erosion can also be exacerbated by instream disturbance or alteration such as gravel removal.
Discouraging gravel removal
Gravel removal should only be undertaken in a justified, co-ordinated and sustainable manner with minimal impact on biological diversity and natural river processes. In general, we discourage the removal of any instream gravel or any interference. Only in exceptional circumstances (e.g. risks to infrastructure such as outfalls, intakes, and bridges) or other sustainable activity (e.g. flood risk management and water supply) can it be considered, and then only following consultation and agreement with Inland Fisheries Ireland and other relevant agencies. If there is no significant risk to these activities, then the requirement for gravel removal must be reconsidered.
When gravel can be removed
Where river gravel removal is being considered, we must be consulted initially to determine if work can be undertaken without impact on the fish habitat. (See other permissions below). The person removing the gravel must provide a detailed method statement outlining the timing, duration, location and justification for the proposed gravel removal along with appropriate mitigation measures to be implemented when removing the gravel.
Gravel must only be removed from dry spoil heaps on the depositing bank of a stream or river to levels above the median flow levels. That is, the water level that occurs most frequently. This is the “normal” river level and will lie above the dry flow level and below the top of bank level. Gravel must not be removed from the substrate or wetted part of the river bed. An agreed distance between the wet edge of the channel and the area of removal should be maintained.
There must be no negative impact to fisheries habitat (including water quality) as a result of the proposed gravel removal.
Activities should not be carried out during periods of drought or when water levels are unusually low. Track machines should not enter the river and all gravel removal should be carried out from the bank. It is important that the bank or riparian zone is not damaged or disturbed during the process. Persons proposing to remove gravel from rivers and streams must use appropriate measures to:
- Minimise sediment mobilisation
- Ensure no negative impact on biodiversity
- Ensure there is no increase to flood risk or detrimental impact on property
- Ensure no introduction of invasive species as a result of the gravel removal
Before beginning any gravel removal, invasive species should be identified with any work required carried out in accordance with IFI invasive species and biosecurity documents which can be found in our Research and Development divisions.
Under no circumstance should gravel leave the property unless in accordance with relevant legislation e.g. Planning or where it is considered that gravels should be reintroduced upstream (as advised by us).
Persons proposing to remove gravel should satisfy themselves that they do not require planning permission for such activity and may require an official determination under the planning regulations from the relevant Local Authority.