Land use and soil type indicate that the significant issue is sediment. The significant pressure is hydromorphology – channelisation: evidence of deepening and straightening.
Athy Stream: Widespread sediment issues have been identified.
Ongoing work by ASSAP may help reduce the amount of new sediment entering the stream.
However, this will not resolve issues with historic sediment and possible impacts from historical straightening of the channel. There may be need for additional restoration work on this river, however as yet there is no framework for river restoration measures in these scenarios.
Recent research presentation to Water Forum, by Irene O’Callaghan UCC, highlighted a huge knowledge gap on sediment contamination, recommendations led to discussion at CMSC.
More monitoring is needed, no regulations in place, would recommend pilot projects.
Lake sediment is an issue and there is lots of unpublished research in this area. It would be useful to collate this information.
Sediment is the 2nd most important pollutant in water after P. It is not well understood and is significant in lakes and estuaries but unsure about its significance in rivers.
Thanks to Irene O’Callaghan
PhD Candidate, MESA Research Group School of BEES & School of Chemistry |University College Cork |
Currently in Ireland there are extremely high siltation levels which are a cause for concern in respect to ecological habitats and fish spawning grounds as well as being sinks for phosphorous and other contaminants.
Based on evidence from the EPA and LAWPRO, poor practice in the drainage of rivers and land drainage have been identified as causing widespread environmental impacts.
The main sources of silt include
poor agricultural practices (e.g. drainage, lack of buffers etc.),
poor practices in channel maintenance,
poorly managed operations in legacy forests and
peat extraction / wind farms / quarrying
Suggested source control measures, such as catch crops and appropriate riparian margins, along with the development of land management plans.
Additional measures include planting of more trees, stopping access of cows and sheep into waterways and an increased protection of existing flood plains
Measures to tackle other significant issues will also deal with the issue of siltation.
Forestry and siltation
Site disturbing operations such as cultivation, road building and harvesting when combined with heavy rainfall pose a high risk of silt runoff into waterways. Great care is therefore required in carrying out these operations to ensure that the measures in the Forests and Water Guidelines are followed. Silt has the effect of smothering streambeds and decreasing oxygen levels in the water which can greatly affect the fish and micro invertebrate life and even change the structure of the physical habitat.
Further information of forests and siltation can be accessed at: