The Scottish Executive had postponed its decision on the power station several times. But two weeks ago it finally gave its approval on the project, which will cost more than £140 million.
Hochtief is preferred bidder following a long period of negotiation and scheme refinement.
The company fought off interest from a Morgan Est/Skanska joint venture, which was frustrated by the year-long wait to find out whether it had landed the project.
A source close to Morgan Est said: 'It got really frustrating waiting so long, the decision was announced a year after first anticipated and we just had to sit and wait, not knowing whether we would get the contract or not.'
Hochtief business development manager Mike Robertson said: 'The client has been very careful in appointing a contractor. SSE has had to wait for clearance from the Scottish Executive and has had to agree on various environmental issues, so it has taken some time.'
Scottish and Southern Energy's 100 MW power plant will create 400 jobs during its construction stage and provide electricity to 25,000 homes in the area when completed.
The scheme involves collecting water to create a new reservoir 600 m above Loch Ness. The reservoir at the top of Glen Tariff will be impounded by a dam, whence water will descend to an underground power house then spill out into Loch Ness.
Preparatory work will start next month, with full construction getting under way in the spring of 2006.