THE TASK AHEAD Can the problems besetting Westport’s Carrowbeg River be resolved, so that any flood risk is minimised and the health of the river maintained?
Country Sights and Sounds
A quick glance into the Carrowbeg River as it flows through the prettiest town in Connacht tells us all is not well. It is becoming unsightly and, like many Irish waterways, a bane for planners determined to build on flood plains.
The matter is hardly straightforward, for in periods of low rainfall it barely flows at all, while heavy rain within the catchment brings the prospect of the Carrowbeg spilling into Westport’s streets as it has threatened to do multiple times, and occasionally has done.
What has happened, so as to cause such irregularities in the flow? And what can be done about it, to restore the river to its pristine condition and also to prevent catastrophic flooding in the future?
The first thing we must acknowledge is that rainfall events around the world are becoming accentuated. Australia, India, China, parts of the United States and more have all been in the news lately. County Mayo is not immune.
Climate scientists have been warning us for decades. Global warming (now often referred to more pressingly as global heating) will lead to a massive increase in evaporation from the world’s oceans. All that evaporated water cannot stay in the atmosphere, but must come down – and down indeed it has been coming!
Imagine setting out on a long car journey. Shortly after departure the restless toddler in the back seat cries out impatiently, ‘Are we there yet?’. What do you say?
In terms of whatever is happening to the climate we are not far down the road. We are nowhere near the place we are told we are heading, and we shall soon be locked into a long, downhill one-way system, the brakes are failing and the vehicle is beginning to career out of control. Worse, nobody really wants to fix a thing, for doing so would mean major lifestyle changes.
We have dug deep ditches and inserted drains to carry water from farmland. We have straightened and deepened rivers and streams and stripped the hills of woodland that formed a natural soak pit. Water that formerly percolated slowly through the soil now runs straight off it, creating flash floods. The wet ground that we hastily drained was formerly a natural reservoir that kept the river healthy through dry periods; now it shrivels at the hint of a dry week.
And why have we done these things? Because we are greedy, that’s why. And as long as we stay greedy we shall never find a solution, but will continue to squander the security of our children in pursuit of short-term gain. If that should sound cynical or even angry, it is neither. We are where we are.
When it comes to finding solutions, nothing is straightforward. There is no quick fix. Further deepening and straightening the river course, as some feel is appropriate, will only serve to move water faster, whereas what is needed is to slow it down.
The most efficient way and perhaps the only way to do this is to restore the wetlands, replant lost forest and replace the sinuosity of the natural stream.
A second and related problem is the amount of weed growth and algae that presently fills the river as it goes through the town.
There is only one reason weeds and algae are growing – there is far too much nitrogen and phosphate in the water. When farmers spread slurry or apply artificial fertiliser to their fields, the same rain that runs straight off carries far too much of it into the river. Poorly designed septic tanks must bear some measure of responsibility too. Those that flood or that otherwise work inefficiently will be feeding the algal blooms.
As well as being unsightly, all that algae will have a detrimental effect on water life. By day it photosynthesises, releasing oxygen into the water. But at night it does the opposite and absorbs dissolved oxygen, depriving fish and other creatures of that essential element and leading to suffocation and death.
Cooler weather will bring a die-back of algae, and as this decomposes it will lead to a further reduction in oxygen availability. Anaerobic bacteria will flourish and the beautiful Mall river will begin to smell, with obvious consequences for local tourism.
These same problems are being experienced the length and breadth of the country. We are learning, albeit rather slowly, that pushing the natural environment out does not work.
But how can these issues be resolved, so that future flooding events are minimised and the health of the river maintained? Could we once more enjoy that bed of clean pebbles the Mall river was designed to be? Your own views are invited.
Michael Kingdon formerly wrote these columns under the pseudonym John Shelley. A naturalist and keen fisherman, he lives close to the shores of Lough Carra.