Building a new $5.2 billion Tappan Zee Bridge will not threaten the survival of the Hudson River's endangered Atlantic sturgeon population, but the project must take precautions and federal monitors should be on hand to track construction, according to a new report.

Recommendations in the long-anticipated study prepared by federal marine biologists gives state officials the greenlight they need to speed onward with fast-tracked bridge plans to put shovels in the ground by year-end.

However, environmentalists are still poring over the 173-page biological opinion released June 22 by the National Oceanic and Atmospheric Administration.

"Riverkeeper is reviewing it very carefully," said Tina Posterli, spokeswoman for the Ossining-based environment group.

The study concludes that construction is likely to "adversely affect" but will not "jeopardize" the continued survival of the Hudson River's two endangered species -- the Atlantic sturgeon, which was declared endangered in February, and the short-nosed sturgeon, which has been endangered since 1967. The region is home to the country's largest population of short-nosed sturgeon.

Construction activity such as noisy pile driving, dredging and drilling will have limited impact on these fish, according to the study. The report sets limits on the number of each sturgeon that can be acceptably killed, caught or injured during construction.

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Protecting the fish is one of several major environmental issues facing the new Tappan Zee bridge project. Other concerns include the impact of dredging -- which will stir up metal toxins, herbicides and other industrial contaminants that have settled on the river's bottom -- and noise pollution from pile driving in the river that is essential for building the bridge's foundation.

During dredging, the report recommends hiring federal monitors and keeping track of underwater noise.

A range of environmental concerns have been documented in the project's Draft Environmental Impact Statement. State officials are reviewing public comments to the DEIS, which will be included in a Final Draft Impact Statement expected later this summer.

"The environmental impact statement is designed to help us build the bridge while being as transparent and responsive as possible to environmental issues," said State Thruway Authority spokesman Shane Mahar. "The final statement will include responses to all public comments, disclose potentially adverse environmental issues that have been identified and discuss our strategies for mitigating them."