Water supplies resumed on Wednesday to almost 200,000 people along the three distributaries of Hanjiang river affected by an algae bloom, local authorities of central China's Hubei Province said.
The algae bloom had turned the water red since Sunday, forcing authorities to cut supplies to nearby residents and eight schools.
Five water companies in Qianjiang City resumed supplies at 9:00 AM and another company in Jianli County resumed supply at 5:00 PM, according to the provincial environment bureau.
"Laboratory tests show that a bloom of maroon cyclotella has been identified as the cause of the abnormal water color," said He Shibiao, vice director of Hubei Provincial Environmental Protection Bureau.
Unlike the toxic blue or green algae, maroon cyclotella has a fishy smell, is innocuous and will not affect drinking water, He said.
Tests on the water from Jianli and Qianjiang sections of Hanjiang river showed the amount of cyclotella reached 100 million parts per liter, ten times the amount that could cause algae bloom.
The water from the three tributaries have been safe to drink after water from nearby Changhu Lake diluted the pollutants, said He.
But tests on Tuesday showed that the permanganate index as well as ammonia and nitrogen levels were slightly higher than the standard.