Algae choking Siem Reap River

People use fishing nets to remove algae from the Siem Reap River on Monday after the river was dammed by authorities to maintain the aesthetics of Siem Reap town for tourists. LAURA WEBER

Mon, 16 May 2016 ppp

Bun Sengkong and Alessandro Marazzi Sassoon

Authorities said yesterday they were clearing an algal bloom in the Siem Reap River, which has been dammed since before Khmer New Year to maintain the area’s appearance.

Poung Lyna, the head of the Siem Reap department of environment, said the unsightly green bloom was being cleared with mesh nets.

“Authorities stopped the water from flowing downstream [so] it became stagnant, and with exposure to sunlight and with photosynthesis, the plankton [blue-green algae] bloomed.”

According to Lyna, the decision to stop the water flow at the Ang Kroper Dam – just south of town near the Ang Kroper crocodile farm – was to allow for Angkor Sangkran celebrations to occur with the traditional use of Pratip floating lanterns.

“We didn’t have water in the river because of the drought, so we had to [dam the river],” he said, adding: “The farmers [downstream] have finished farming, and they do not need much water.”

Local officials from downstream communities told the Post that the damming did not have any adverse effects. According to Tek Vann, the deputy head of the provincial environment department, the primary purpose of damming the river was aesthetic.

“The water exists to beautify the city for tourists,” he said.

Asked whether the stagnant water posed any public health concerns, Vann said that it could be a breeding ground for mosquitoes and toxic for humans.

“I warned people against drinking it and washing in it. It is not safe to even wash yourself with the water,” he said. “The workers who removed the algae said they have skin rashes,” he continued. “Only the poor use it to wash their old clothes.”

Vann also noted that hotels alongside the river also spray “anti-mosquito substances”.

According to the UN Environmental Program, algal blooms are a sign of eutrophication, a process that can result in loss of biodiversity and water becoming toxic from algal byproducts.

Bun Hean, secretary of state at Ministry of Water Resources and Meteorology, said the decision to dam the river was made by the Apsara Authority, not the provincial department. An Apsara authority spokesperson was unable to provide information as of press time.