Contractors doing business with the county paid thousands of dollars for a picnic for Harris County Toll Road Authority employees last year and were about to be asked to do so again, officials with the county and district attorney's office said Monday.

Details, including plans to recognize vendors as gold- or platinum-level donors based on how much money they contributed to this year's picnic, were confirmed Monday in response to questions about the abrupt retirement of Toll Road Authority Executive Director Mike Strech last Thursday.

Strech, who headed the agency for six years, and his executive assistant Diana Wilcox, quit after being confronted about the planned solicitation, Harris County Public Infrastructure Department Director Art Storey said.

The annual event was held last year at SplashTown in Spring and was scheduled there for mid-July until county officials canceled it. Storey described the party as a long-standing event typical of the authority's "culture."

"If somebody who hasn't been part of that culture observed things that were perceived to be normal there, they might say, 'Gee that looks bad — that's questionable, that's borderline illegal,' " Storey said. "It's not people knowingly acting wrong. It's people who don't know any better, and we're going to fix that."

Strech, 67, who worked for the Toll Road Authority for 16 years, declined to comment Monday, except to say the picnic was a tradition and that he planned to "enjoy my retirement."

Wilcox could not be reached for comment.

Harris County District Attorney Chuck Rosenthal said an investigation by his office found no criminal wrongdoing.

"It would be a violation if the vendors were being solicited to do this in order to get contracts for the toll road," Rosenthal said.

"Nobody that we talked to felt arm-twisted to make any contributions," he said. "We looked into a bunch of records and found ... that there was nothing criminal that could be proven."

However, Rosenthal added, the county auditor's office is looking into the matter.

"If the auditors find something, I'm sure they'll come back to us," he said.

Storey said he consulted County Attorney Mike Stafford after toll road staff called his attention to an in-house e-mail from Wilcox about the upcoming event.

Storey said he had told Strech last year not to accept vendor gifts for the next picnic, then learned that this was apparently planned. Storey said that when he asked Strech about it, the director showed him a draft of a letter to be sent to vendors.

District attorney's investigator Dan McAnulty said vendors were classified as bronze-, silver-, gold- and platinum-level contributors for gifts ranging from $500 to $5,000.

Similar letters signed by Strech were to be sent to several companies, each doing at least $100,000 in annual business with the county, McAnulty said.

He and Storey declined to name the companies, but Storey said most are engineering firms that are hired on the basis of credentials instead of the sealed bids used for construction contracts.

Storey emphasized that Strech neither had nor claimed any authority to award contracts, which are approved solely by vote of Commissioners Court.

McAnulty said donations were placed in a Bank of America account in the name of the Toll Road Authority Celebration Committee, which he described as a "social committee" set up last year.

Such an account is "clearly improper because it was off the county's books" and would not be noticed in a county audit, County Attorney Mike Stafford said.

About $15,000 was in the account, apparently left over from last year's party at SplashTown, for which $60,000 had been collected — and $45,000 spent — from 29 contributors, McAnulty said.

He said about 1,400 people attended that event, including HCTRA employees and guests of vendors, who received tickets based on their contributions.

Although the Texas Penal Code forbids gifts to a public servant, the recipient would need to "exercise discretion in regards" to contracts or purchases for that to apply. Storey said neither Strech nor the celebration committee members had that power.

Precinct 3 Commissioner Steve Radack said huge parties by the Toll Road Authority and its vendors were nothing new.

When the Sam Houston Tollway was completed, he said, there was a large crowd "rocking" to a band on one of the towering ramps, and some observers "got to worrying that the thing would collapse."

Before 2006, McAnulty said, the annual picnic was held at a local ranch, with vendors writing checks directly to the ranch. But last year, he said, the committee's bank account was opened to receive contributions.

It was not immediately known how much SplashTown may want from the county for booking, then canceling, the event. Storey said he understands the county will contend that the contract is invalid because Strech lacked the authority to sign for the county.

Storey said he has named Gary Stobb, the infrastructure department's director of planning and operations, to serve as interim director of HCTRA. In previous years he also assigned two other infrastructure officials, Ronald Krafka and Peter Key, to jobs at the toll authority.

Storey said he sent out a message addressed to "vendors, suppliers, consultants and sales executives."

It advises them, among other things, to "never make a monetary gift" without his permission, to any of the agency's staff "for any purpose whatever, no matter how worthy the purpose intended."

Chronicle reporter Bill Murphy contributed to this story.

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