With all their modern scientific equipment and state-of-the-art computer models, researchers trying to better understand the effect of algae growth in Lake Tahoe are searching for new tools to aid in their mission — old photo albums.

Experts at the UC Davis Tahoe Environmental Research Center said in an annual report last week that the mountain lake is still getting warmer, regional winters are still getting shorter and snowfall is still on the decline.

Water quality also has worsened a bit.

What is less clear, however, is the trend in long-term algae growth.

"Everyone wants to know if there's more of this stuff, but we don't know," said Geoff Schladow, a professor of water resources and environmental engineering at UC Davis.

Researchers study algae growth because it is linked to high levels of nutrients, which enter the lake both atmospherically and through stormwater runoff. Fertilizer, for example, contains nutrients and can find its way into the lake when it rains, thus contributing to algae growth.

"We have low rainfall and low sediments coming in. You would expect the clarity to be better," Schladow said last week during a presentation on the campus of Sierra Nevada College in Incline Village, according to the Sierra Sun (http://tinyurl.com/jbapc5y).

But despite a reduction in the amount of sediment entering the lake last year because of the ongoing drought in the West, the concentration of nitrate is actually higher.

The problem is, scientists have already been measuring algae growth at Tahoe since the 2000s.

"What we're left to use is anecdotal data," Schladow said. "We also ask for old photos, so if anyone has some they'd like to share, unfortunately that is the only older data we have."

Scott Hackley, a staff research associate at UC Davis, said he's worked with archivists at the University of Nevada, Reno, to find old photos, but he and his team are hopeful that the community can help as well.

"It'd be nice to get some old photos with the year, time of year and the location . to fill in some of the historical gaps," he said.

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Information from: Tahoe Daily Tribune, http://www.tahoedailytribune.com/