Friday, February 22, 2013

Report findings mixed, but overall, lake is healthy

For the past 26 years, volunteers with the Smith Mountain Lake Association and Ferrum College have kept a watchful eye on the lake's water quality.

The newly released 2012 water quality report indicates that "Smith Mountain Lake continues to be a healthy body of water for all forms of water recreation," according to Larry Iceman, the SMLA's water quality monitoring program chairman.

The report indicates that there are a couple of anomalies that will need further investigation. For example, the total amount of phosphorous concentration in the lake decreased by a third, said Iceman. "We think it's because it was a dry summer, and, therefore, there was less food, nutrients and fertilizer coming off the land and washing into the head waters," said Iceman.

Lower phosphorous levels are good because that's what algae feed on, said Dr. Carolyn Thomas, professor of environmental sciences and biology at Ferrum College and director of the Smith Mountain Lake Water Quality Monitoring Project.

Phosphorous can enter the lake through runoff (from rainfall) and from other different land uses, such as fertilizing. The more phosphorous there is in the lake, the more algal growth there tends to be.

Once phosphorous enters the lake, it stays in the lake, said Thomas.

While less phosphorous typically means there's less chlorophyll-a in the lake, the levels of chlorophyll-a actually increased by about 60 percent this year, reported Iceman.

According to a previous water quality monitoring report, "Chlorophyll-a is extracted from algae and is a measure of the algal population."

At the same time, the Secchi depth (water clarity) in the lake remained constant.

"Secchi depth is a measure of water clarity that decreases as algal populations and siltation increase," stated the report.

"We're not quite sure why those didn't track," said Iceman of the phosphorous, chlorophyll-a and Secchi depth measurements. "We're going to look and see if those trends continue."

Another trend that requires further investigation is that the blue-green algae and diatoms measured higher than green algae. In short, green algae and diatoms are considered good algae, said Thomas, while the blue-green algae can have a negative impact on lake quality.

"We had more blue-green algae than we've seen in the past," said Thomas.

Both Thomas and Iceman also pointed out that the population of bacteria - such as E. coli - continues to remain at low levels.

"The good news out of all of this is that we are once again way, way below [state levels] in terms of bacteria populations," said Iceman. "That tells us that animal and human waste are not causing health hazards."

The water quality monitoring program has about 40 monitors who sample 80 sites around the lake, said Iceman. The monitoring season typically lasts about 12 weeks and begins around the end of May. Each year, volunteers attend a training program in the weeks before sampling begins.

Iceman, who's been a water quality monitor for about a year, recently took over the SMLA's water quality monitoring project chairmanship from lake resident Stan Smith, who was chairman for more than a decade.

Even though Iceman is a relative newcomer to the water quality work, he praised Smith's long-time efforts and the continued partnership with Ferrum College. He also expressed appreciation of the volunteer monitors who collect the samples.

"I've been told that the quality of the work we get from the volunteer monitors is comparable to that of professionals who do monitoring work on other lakes," said Iceman. "Between us and Ferrum, we have a pretty good handle on what's going on."