The contractors are working on another project in India and council chiefs are not even sure they will return to finish the job, it is reported.
The reef is a key part of the Boscombe Spa development and costs for the whole project have risen by a third to hit£11m, reports the Daily Echo.
It says the council has approached other companies in case the hired contractor ASR does not return from another reef project in India to finish the work.
The ref is 60% built but work was suspended for the winter and the contractors, ASR is said to have been delayed building another surf reef in Kerala.
The council will now have to pay£100,000 towards ASR’s bill of nearly£300,000 for shipping their equipment to and from India - assuming they remain on the project.