An enforcement notice has been issued to contractors working on the Aberdeen bypass after freshwater pearl mussels, salmon and other fish were put at risk from pollution.

The Scottish Environment Protection Agency (Sepa) is actively investigating construction work on the Aberdeen Western Peripheral Route (AWPR) following the incidents in various tributaries of the River Dee and the River Don.

The risk is considered so great to the sensitive freshwater pearl mussel and salmon habitats of the River Dee that an enforcement notice has been issued to those working on the bypass in a bid to prevent any more pollution.

Andy Rosie, Sepa’s head of operations for the north, told The National: “Sepa has significant concerns that construction activity on the AWPR poses an ongoing risk of pollution and has resulted in environmental impacts to the water environment.

“An enforcement notice has therefore been issued to the company involved which will require urgent action to be taken on the pollution prevention measures necessary for protection of local watercourses in the vicinity of Cleanhill Wood, near Burnhead.

“These tributaries flow into the River Dee, designated as a special habitat for both salmonid fish and fresh water pearl mussels, which rely on a delicate eco-system to feed and spawn. The erosion of silt from the construction site poses a risk to the quality of the water and can settle out onto the bed of the rivers and streams, blanketing and damaging aquatic animals and plants.

“We are requiring the contractor responsible to take immediate and effective action to stop silt pollution entering and contaminating the local watercourses surrounding the AWPR site. Our officers will be monitoring progress closely over the coming months, and will not hesitate to take further enforcement action if necessary to prevent further pollution.”

The AWPR/B-T project is being delivered by Transport Scotland, the national transport agency, on behalf of the Scottish Government and in partnership with Aberdeen City Council and Aberdeenshire Council.

Aberdeen Roads Limited, a joint venture including Balfour Beatty, Morrison Construction and Carillion is constructing the new 36-mile road.

A spokeswoman for Transport Scotland said: “We are aware of the points being raised by Sepa. The AWPR/B-T contractor has already put additional mitigation in place including the further enhancement of existing mitigation near watercourses. We take these issues very seriously and are currently working with the contractor to ensure that the matter is resolved as soon as possible.”