Residents and nature lovers say not enough action is being taken to stop an unwanted substance getting into Clipstone Brook in Leighton Buzzard.
Less than a month after the alarm was raised over a red dye seeping into the brook, residents say there are still problems.
Leia Blakesley, a member of Bedfordshire Wildlife, said there had been several incidents at the brook in the past month, caused by concrete firm Forticrete based on Boss Avenue in Leighton Buzzard.
"It doesn't seem to be getting any less," said Leia, "It always seems to happen when it rains."
The Environment Agency investigated the first leakages and say they will be investigating the latest concerns.
An Environment Agency spokesman said: “More investigations are underway, but we believe new reports of red dye in the River Ouzel are due to heavy rain flushing out granules from the original spill, and are thankfully not a new problem.
“Following advice from our specialist officers earlier this month, the company concerned put measures in place to prevent further incidents.
“If anyone suspects pollutions in our rivers, they can call our incident hotline on 0800 807060.”
Forticrete did not respond to requests for interview from the LBO but in responses via social media to concerned residents it said: "This week following further significant rainfall some residual non-hazardous material has washed out of the drain and discharged into the river.
"At Forticrete we have extensive control procedures in place with regard to our water control and we are currently working with a specialist company to prevent any further incidents from occurring.
" As a business, we take our environmental responsibilities extremely seriously. A few weeks ago, following a period of heavy rain, a small amount of non-hazardous material left our site through the surface water drain, which discharges into the local river. We immediately contacted Anglian Water and the Environment Agency, who have since visited our site and are satisfied that the material has no environmental or safety concerns".