People living along River Athi have been cautioned against using its water which has turned green due to pollution.
Addressing the press Mavoko MP Patrick Makau said the fish and water was not fit for human consumption and would be dangerously harmful for any user due to the sewage and industrial chemicals channelled into it.
The legislator noted that raw sewage, industrial waste are disposed of directly into the river.
Makau observed that despite the fact that he supports the growth of industries as much as he supports the growth of industries things must be done in an ethical and proper manner.
"We have witnessed dead fish floating in the river, an indication the water was lethally polluted" he said.
He asked the National Environment Management Authority (Nema) to warn owners of upcoming factories and construction sites in Athi River against polluting the environment.
He further called on the Machakos County government to intervene in a bid to ensuring favourable sanitation to its residents.
In the recent past residents downstream have raised the alarm over the pollution, which threatens the river's entire ecosystem.
Thwake Dam, which will be constructed at the confluence of the Athi and Thwake rivers, is also likely to be threatened if the pollution of River Athi remains unchecked.
On Monday pictures of dead fish floating on River Athi surfaced online.
National environment and management authority on twitter confirmed that samples from the river had been taken for testing.
"A Multi-agency team including NEMA, WRA, Public Health and @Environment_Ke have today visited the section of Athi River where fish have been affected by recent pollution and collected samples for testing at Gov't chemist. Surveillance ongoing to identify the source of pollution." read part of the post.