Tetra Tech Inc., an environmental engineering firm based in Pasadena, has won a $25 million contract with the U.S. Environmental Protection Agency, the company announced Thursday.

The five-year contract includes work on water pollution prevention and water infrastructure construction projects.

“The new contract expands Tetra Tech’s technical support of EPA’s West Coast watershed and coastal protection programs,” the company said in a statement.

All the work will occur in EPA’s Region 9, which covers California, Arizona, Nevada, Hawaii and other Pacific islands.

In mid-morning trading, shares of Tetra Tech had lost 87 cents, or about 3 percent, and were trading at $27.42.