They said fingerlings were struggling to breathe.
Yala Swamp Community Conservancy Organization secretary George Odero said the lake was full a few weeks ago as a result of the rains pounding various parts of the country.
“We have communities and an investor interfering with water flow to the lake,” Odero said.
Odero said the community had blocked the outlet while an investor has interfered with the inlet in order to control the amount of water into the lake.
He said the artificial outlet was removed by the investor to allow water to get out of the lake and breath.
“The overflow was too much and the water broke the dyke that was weak,” Odero said.
Odero said the breakage of about two meters allows huge volumes of water into the swamp at high rates.
He said some fish have died while others have escaped into the swamp.
The conservancy has since written to various government agencies to address the challenges.
On May 12, Yala Swamp Community Conservancy Organization Chairman Steven Okumu and Women in Nature Kenya Chapter representative Dr Judith Okello wrote a letter to government offices raising concerns over the issue.
They said Lake Kanyaboli is very crucial as it constitutes part of the Yala Swamp complex which forms the mouth of both the Nzoia and Yala rivers.
“It is one of the most important riparian satellite lakes found around Lake Victoria. The lake is a very important habitat for populations of certain fish species, which have since disappeared from Lake Victoria,” they said.
The two officials said the lake forms a great sight for bird watching and sightseeing with possible sightings of rare Sitatunga.
“Lake Kanyaboli forms an integral component of the local community who depends on it for its water, fisheries as well as papyrus reeds for basket and mat weaving.”
The officials said the lake has in the past couple of weeks suffered a great setback that would soon put this important ecosystem only in historic books with nothing to see or benefit from.
“The lake is losing its waters at an alarming rate due to the removal of outlet plate and the closure of inlet by unscrupulous developers. The plate had earlier been fixed to regulate the amount of water getting out of the lake,” they said.
The conservationists said an enormous number of small fish were found wading on mud by locals as the lake quickly retreated on May 12.
“With this letter, we request your office to take immediate action to salvage the situation that is slowly getting out of hand.”
The letter has been copied to the Siaya County Commissioner, Siaya National Environment Management Authority director, Kenya Forest Service Regional Forest Conservator and Director of Kenya Wildlife Service.
Others copied include the Director of Kenya Marine Fisheries Research Institute, Water Resource Authority Director, County Director Ministry of Environment, CECM Agriculture Siaya, and Nature Kenya.
Nema officials, KWS and the Water Department are reported to have visited the site.
Last year, Yala Swamp was at the centre of controversy after the National Land Commission allocated it for agricultural use.
In September 2022, NLC allocated Lake Agro Farm 17,048 acres of land at the Yala Swamp in Siaya County for agricultural use.
Conservationists were against the allocation.
NLC commissioners Reginald Okumu, Esther Mathenge, James Tuitoek and Tiyah Galgalo made the determination after holding a series of public hearings of the intended allocation to Lake Agro between June 13- 16, 2022 in Siaya.
Lake Agro Farm will seek to invest Sh20 billion to do commercial rice, fish, soya and sugar cane farming to reclaim the Yala Swamp.
The investor is, however, expected to enter into an MoU with the county government of Siaya and local communities to capture the roles and responsibilities of parties for purposes of resource management anchored in the Yala Delta Land Use Development Plan.