A construction firm has been fined £10,000 after breaching island pollution laws.
Legendre Contractors admitted causing pollution to controlled waters in Elizabeth Marina, Jersey.
The offences happened between 20 February and 6 April when the company was working on the States-backed Horizon development.
Incorrect information on ground-work surveys resulted in the firm drilling into a sea wall.
The historic sea wall was discovered in November 2018, despite two surveys indicating there was nothing there.
After sea water had entered the foundations of the development, sediment parts known as suspended solids drained into the marina.
Defence Advocate James Angus said the French firm "did not foresee" the effect of removing the wall, and worked quickly to stop pollution from spreading.
Magistrate Bridget Shaw agreed the company took "appropriate steps" once it was made aware.
She said the pollution was "not deliberate, but a failing on the part of the company" and there was "no actual harm to marine life, and a low risk".
The firm was issued with the maximum fine possible from the island's magistrate's court for this type of offence.
The development includes 280 apartments, and 20,000 sq ft of commercial space for shops, cafes and restaurants.