Up to 200 people have gathered on a bridge over the River Shannon in Banagher in Co Offaly to highlight the concerns of farmers and residents along the river about rising summer water levels.
Thousands of hectares of the Shannon Callows, land either side of the river between Athlone and Portumna, are inundated after the wettest July on record.
Farmers dependent on the Callows meadow for hay and silage are facing fodder shortages later in the year.
The Shannon Callows are the natural flood plain of Ireland's longest river. Every winter when water levels rise, they flood as part of a natural cycle.
In recent years, however, summer flooding has occurred more often and after last month's rainfall exceeded all records, the Callows are again under water.
For farmers this is very bad news, according to Padraig Coughlan who owns Callows land in Fardrum, 8km down river from Athlone.
"No one got a chance to cut any of the Callows. The water just came in and it just kept rising and rising. People involved in eco-schemes are not allowed cut until 1 July, 15 July or 1 August, but there will be none cut this year now and it will be a loss of feed for cattle, and the loss of wildlife," he said.
Standing in a meadow of lush green grass and herbs but also in 10cm of water, Mr Coughlan said the flood waters rose in the last couple of weeks after very heavy rain.
"At the start of July, it was looking good, the Callows were looking good, but once the rain started, in two days the Shannon came out over its banks. The water is not able to get down and it's getting worse every year."
Irish Farmers' Association Connacht Regional Chairman Pat Murphy said the loss of Shannon Callows silage and hay is devastating for farmers in the region.
"It's a huge loss to farmers in this region. We are talking about something like 20,000 bales of silage. People honestly thought they were going to be able to get the Callows, but that’s not the case. Going into the winter we don’t know where we are going to be. It will mean a huge cost to farmers to have to replace this fodder," he said.
Farmers are calling for better coordination in the management of the River Shannon, which falls under the responsibility of a number of bodies.
They include the Office of Public Works (OPW), Waterways Ireland, Inland Fisheries Ireland and the ESB.
Those bodies do consult one another over water level management, but farmers want a single body to manage the system and a seat at the table when decisions are being taken.
"We need to be included in one management body, where we can sit around the table as important stakeholders so we can explain what's important for us rather than us contacting the OPW and they contact the various different agencies," Mr Murphy said.
The Save our Shannon Organisation staged the demonstration on Banagher Bridge, where chair of the group Michael Silke called for a single management authority to be put in place to coordinate water management, with a place for farmers and local residents to be heard.
In a statement, the OPW said the preparation of legislation to improve the management of flood risk on the River Shannon is a Government priority.
As part of this work, the OPW has conducted an analysis of existing legislation regarding the management of the River Shannon, including a review of the powers of various bodies involved with the river.
The OPW said it is in the process of preparing legislative options for consideration.
