According to Inland Fisheries Ireland, environmental officers have been on site since Wednesday evening to investigate the incident
An investigation between Inland Fisheries Ireland (IFI) and other government agencies is continuing as a significant amount of fish have been killed on the River Rye near Maynooth.
In a statement issued today, the IFI have said early indication suggest more than 500 fish have died.
Fish mortalities were observed over a 4km stretch of the river, with species of fish found dead including brown trout, lamprey, stone loach, minnow and gudgeon.
According to IFI, environmental officers have been on site since Wednesday evening to investigate the incident.
It is also understood that the Environmental Protection Agency, Kildare County Council and the River Basin Management Services have been on the ground today investigating the issue.
In its statement, IFI said the interagency group is actively looking into the cause of the harmful ecological event that took place on the River Rye.
"The interagency group is actively probing the cause of this harmful ecological event, but it’s too early to definitively establish how it occurred:
"IFI is working with other government agencies in line with the new national interagency protocol for investigating significant fish kills, and is the lead agency on this case.
"An interagency group met today to discuss the River Rye fish kill and included representatives from Kildare County Council, the EPA, the Department of Climate, Energy and the Environment, and the National Parks and Wildlife Service."
In 2022, an estimated 500 brown trouts were found dead at the River Rye in Leixlip.
IFI is urging the public to report instances of fish kills, water pollution, habitat destruction, or illegal fishing to its confidential 24/7 number, 0818 34 74 24.

Kfm Obituary Notices
Over €240K Announced For Local Community Groups In Kildare
Kildare TD "Profoundly Concerned" At Defence Forces Recruitment
Open Ground Search For Jo Jo Dullard And Deirdre Jacob Concludes On Kildare/Wicklow Border
New Adventure Park Opens In Donadea Forest
Tributes Paid To Teenager Who Died Following E-Scooter Collision In Carlow Town
Local TD Urges Public To Engage With Castletown/Donaghcumper Masterplan
HSE Make U-Turn Decision And Scrap Plans To Impose Home Care Cuts