The last three months have been a wild Wall Street ride for Pasadena-based environmental and engineering consulting firm Tetra Tech Inc.

In late February, the stock soared in value to an all-time high of $28 a share, fueled by an announcement that the company was looking at spinning off its lucrative telecommunications business.

But in March, the tech market collapsed, forcing Tetra Tech to postpone its spin-off plans. Since then, the company’s stock has come back down 35 percent to below $18 a share, putting it about where it was before the run-up.

“They were almost through with their valuation of their telecom business when boom, the tech correction came and the market value of the business fell precipitously,” said Jeff Beach, an analyst at Stifel Nicolaus-Hanifen Imhoff in San Francisco. “Now they may have to wait until next year before the value is right again, if they decide to go through with it at all.”

So, for the time being, Tetra Tech remains a company with three major operating divisions: an environmental consulting and cleanup business, a transportation and infrastructure building segment, and the telecom business, which builds cabling networks and designs antennae for wireless networks.

The gyrations on Wall Street have not put a damper on the company’s financial performance. In its second fiscal quarter ended March 31, Tetra Tech reported $8.1 million in net income (20 cents per diluted share), compared with $6.4 million (16 cents) for the same period last year. Revenue was $139 million vs. $96 million.

During its most recent fiscal year ended last Sept. 30, the company posted net income of $29.1 million (74 cents per diluted share) compared to $20.6 million (56 cents) for fiscal 1998. Revenue was $432.1 million vs. $297.6 million.

“The fundamentals of the company remain strong and should continue so for the foreseeable future,” said James Janesky, an analyst with Bank of America Securities in San Francisco.

Yet Janesky said Wall Street suddenly cooling to tech right before Tetra Tech’s planned spin-off was a case of unfortunate timing.

“The sizzling telecom market meant that the telecom side of the business could have been valued at more than the rest of the company was worth,” he said.

In fact, company officials say Tetra Tech is right on target, performance-wise.

“Our goal has always been 20 percent to 25 percent earnings-per-share growth since we came to market in 1991; we’re right there now and expect that to continue,” said Li-San Hwang, Tetra Tech’s longtime chairman, president and chief executive.

Hwang said the company has put more emphasis in recent years on the telecom side of the business, because of the intense marketplace demand. He noted that the company has agreements with wireless giants Verizon Wireless (formerly Air Touch Cellular) and Sprint PCS to help install antennae for their wireless networks. Tetra Tech provides the radio frequency calculations to determine where the antennae should be placed.

Just a few years ago, finding suitable locations for these antennae involved much more than mathematical calculations. Neighborhood groups opposed the 50-foot-high poles, calling them unsightly, and city councils across the region had placed moratoriums on the installation of these antennae.

But not any more, Hwang said.

“People are much more accepting of the antennae now because they realize so much information is going through these facilities,” Hwang said. “They know they will soon be able to plug their laptops into these networks and totally bypass conventional phone or cable lines.”

While the telecom side of the business may be the fastest growing and thus the most attractive to investors half of Tetra Tech’s revenues still come from its bread-and-butter business of environmental consulting. The firm has made a big push in recent years in the water quality and treatment area.

“They are the No. 1 company in the U.S. when it comes to consulting on water quality issues,” Beach said. He cited extensive work that Tetra Tech has done on contract for the U.S. Environmental Protection Agency to develop water quality and contamination monitoring standards.

In recent years, as the monitoring technology has improved, cleaning up the nation’s water supplies and waterways has taken on renewed urgency. And as the focus turns to cleanup, Beach said, hundreds of millions of dollars in contracts will follow.