GRAND ISLE, Vt. -- Phosphorus levels continue to be an Achilles heel in the overall management effort for Lake Champlain.

The Lake Champlain Basin Program released its 2008 State of the Lake report Friday afternoon, and officials highlighted statistics that showed phosphorus levels steady or increasing in several areas where the nutrient is a source of concern.

"We're always being asked Is the lake getting better or worse?'" said William Howland, executive director for the Basin Program, as he reviewed the report's findings during a press conference at the Basin Program's Grand Isle office.

That question is never easy to answer, Howland explained, adding that the 32-page document represents the best effort researchers could put forward on the lake's health.

"Lake Champlain is made up of five distinct segments, and each has its own story to tell," he said. "The quality of the water in most of Lake Champlain is probably the envy of every large body of water in the nation.

"Unfortunately, there are parts of the lake that have very high nutrient levels, which supports an excessive growth of blue-green algae."

Those areas, typically in northern sections of the lake such as Mississquoi Bay and the Northeast Arm, have been plagued of late with increased growth of algae and other aquatic plants.

Blue-green algae has been of special concern because it has been known to be toxic and, in fact, has been responsible for the deaths of a few dogs over the past several years.

Research has also shown that phosphorus levels in such places as Burlington Bay and Cumberland Bay have maintained low levels of phosphorus, and efforts to reduce phosphorus levels in discharge from sewage treatment plants has been positive.

However, runoff from agricultural use, storm-sewer runoff and other non-point sources continues to far outweigh levels coming from treatment plants. A graphic from the report shows that 90 percent of phosphorus entering the lake comes from non-point sources.

Communities and individuals can help reduce phosphorus levels by taking steps to reduce runoff from their properties, Howland said, noting that ditches and other methods to move rainwater off property rapidly actually help to increase phosphorus levels.

"When we remove phosphorus from sewage-plant discharge, we see the results rapidly," said University of Vermont Professor Mary Watzin, who is a member of the Basin Program's Technical Advisory Committee.

However, she explained, lowering the levels of phosphorus agriculture and other non-point sources does not happen as dramatically.

"We need to be a bit patient," she said. "It's too early to make a verdict (on whether phosphorus control efforts are paying off)."

The report gives a thorough look at a variety of issues, many of which show positive improvements in lake management efforts. Main sections also target human health and toxins and biodiversity and aquatic invasive species.