Vegetation (Floating River Vegetation) - Office of Public Works

extraction of floating river vegetation during channel maintenance should be applied where a large
amount of floating river vegetation exists especially in watercourses of high nutrient levels. This
approach has successfully worked for reed beds (Ní Bhroin, 2004) and should work for channel
maintenance. Removal of root material provides expansion space for remaining roots therefore
reducing overcrowding, encouraging regeneration of root material resulting in improved nutrient
cycling and reducing the likelihood of disease or stressed plant growth.
• In the case of large amounts of floating river vegetation growth especially in watercourses of
high nutrient levels ½ to ⅔ of the plant material should be removed and placed away from
the watercourse to prevent leaching of the nutrients back into the watercourse.
• In the case of a moderate amount of floating river vegetation less than half should be re-
moved on watercourses with low nutrient levels.
• In the case of limited occurrence of protected plant species it would be advisable to retain all
growth present.
Other Statutory Bodies: In accordance to REPS 3 Measure 3 “The Protection and Maintenance of
Waterbodies and Wells” the emphasis is on the maintenance of channels with option 3a referring to
the proximity of livestock to watercourses. During the course of the survey a number of smaller
channels, outside the remit of the Office of Public Works, were found to be recently regraded,
widened and deepened. Raising awareness of the nature and methodology of regrading and silt
removal work carried out by the Office of Public Works under the Environmental Drainage
Maintenance Programme is essential. Incorrect maintenance upstream may impact negatively on
arterial drainage channels downstream.
• The Central Fisheries Board / Office of Public Works Environmental Drainage Mainte-
nance Programme should be extended to all drainage work on watercourses. This might be
implemented through REPS.
Other Statutory Bodies: Restricting access of livestock to watercourses will reduce the possibility
of eutrophication, destruction of riverbed by compaction, the prospect of floating river vegetation
being eaten by livestock and the erosion of riverbanks (important for water parsnip) by excessive
trampling (Northern Ireland Action Plan, O’Grady, 2006, Hatton-Ellis & Grieve, 2003). In fields
not supplied with piped water supplying access to water at the waters edge which is fenced on all
sides (drinking slips) is an acceptable compromise (REPS 3). River banks eroded by livestock were
observed favouring terrestrial plant species and not aquatic species. Damage to channel banks
appeared to produce the same effect as the build-up of large silt deposits.
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