WINSLOW, Maine — Divers and K-9 units searched the Kennebec River without success Tuesday in the effort to find clues of missing toddler Ayla Reynolds.

Tuesday marked the seven-month anniversary of her disappearance from her father’s Waterville home last December.

“The warden service wanted to eliminate this area as a possibility, and so today happened to be picked,” Maine Department of Public Safety spokesman Stephen McCausland said during a press conference outside Brookfield Power, a Hydro Kennebec station. “It is a coincidence that today is the seven-month anniversary [of her disappearance].”

McCausland said no substantial evidence was found regarding Ayla, who was 20 months old at the time of her disappearance.

The Maine Warden Service and Maine State Police sent 13 divers into the Kennebec River and searched between the hydropower dam and the Bridge Street dam along U.S. Route 201. Dam operators were able to lower the water level between the dams.

“The visibility was fairly good,” said McCausland. “There was about four feet of visibility. The water was murky. It was good diving conditions.”

Nine dogs, both cadaver and tracking dogs, were used to search along the shore.

McCausland said it was the third time divers have searched the river.

“It’s basically a two- or three-mile swath that we have concentrated on here [today]. There may be other areas [searched] in the future,” he said. “It has been checked off the checklist.”

A few items were found, McCausland said, but they weren’t substantial. He wouldn’t specify what was found.

The search for Ayla Reynolds by police has been the most extensive in the state’s history, he said.

“There has been no case in our history that so much time, effort has been devoted [to], and that will continue. The efforts will continue until we find her,” said McCausland.

The efforts up to this point have taken a toll on the searchers, he added.

“We’re not in a dead end,” said McCausland. “There’s been frustration — it’s been seven months. There has been an enormous effort to find little Ayla.

“We’ve obviously been very public in all of the efforts we have done. It is now seven months, and it is hard to believe seven months have gone by, frankly,” he continued. “The reward has come and gone, but the investigation continues and will until we find her.”

A $30,000 reward for information leading to an arrest in the case was offered by Waterville-area businesses, but it expired on June 30.

Tips from the public have slowed, said McCausland.

“We still get the occasional tip. But they have slowed down,” he said.

McCausland reiterated that Tuesday’s search was a part of a continuing effort to find the toddler.

“This is not the end,” said McCausland. “We will continue to search, we will continue to dive, and we’ll continue to look for Ayla Reynolds.”