Heavy rains cloud Norway lakes

NORWAY — Water clarity is down in Norway's lakes, according to a recent report, but the reason has more to do with changes in precipitation than changes in pollution, say analysts.

Lake Pennesseewassee, Hobbs Pond, Sand Pond, and North Pond were all analyzed for levels of water clarity, phosphorus, chlorophyll, color, and PH levels.

The results were mixed.

"Overall, there was a measurable decline in the Norway Lakes in 2009," concluded the report, which was submitted to the Norway select board by the Norway Lakes Association. "This was most probably due to the cumulative effect of two years of very heavy precipitation and runoff."

The report noted that the summers of 2008 and 2009 were banner years for rainfall, with the National Weather Service recording that 2009 was the wettest summer in Portland in the 138 years of recorded data.

The rainfall "carried phosphorus and sediment from the watersheds into the four lakes," reads the report.

Generally speaking, the water clarity in 457 lakes across Maine suffered, according to a DEP-sponsored volunteer monitoring program. Approximately 50 percent of lakes are less clear than their historical averages.

While  the weather creates a significant impact, "the natural rate of flushing, the extent of watershed development and other influences play an equally important role for individual lakes and ponds," noted the report.

Statewide, the average water clarity is about 5.3 meters. Lake Pennesseewassee (5.7 M) and Sand Pond (7.2 M) are clearer than the state average.

Hobbs Pond, with a clarity of 4.9 M, is below the average, and significantly below it's 2008 measurement of 5.7 M.

North Pond is only 2.7 meters deep, and so it is only possible to say that it is clear to that depth.

One of the biggest areas of concern is the level of chlorophyll-a (CHL) in Pennesseewassee and Hobbs Pond. CHL is a pigment that is used to measure algae concentrations.

After four years of CHL concentrations well below five parts per billion (ppb), 2009 tests showed an average concentration level of 5.5 ppb in Pennesseewassee. One reading, conducted on July 23, was 9.7 ppb, more than double the average reading of 2005 through 2008.

In Hobbs Pond, the CHL counts were 5.8 ppb, with a high of 7.8 ppb in June.The historical average for the pond is 4.9 ppb.

Another concern is the distribution of phosphorus in Sand Pond. Plentiful levels of phosphorus can trigger growth in problematic algae in Maine waterways.

Samples taken from the deepest depths of the pond (56 feet) show phosphorus concentrations "nearly five times as high as a sample taken near the surface," according to the report.

"This suggests that the pond is in a very sensitive state," reads the report, "and that water quality could change if conservation measures are not employed for both existing and new developments in the watershed."

One bright piece of news was a complete lack of invasive aquatic water plants in any of the four lakes. Milfoil and other invasive plant species have become a problem in many of Maine's lakes and ponds, including Bryant Pond, Hogan Pond, and Thompson Lake.

Local monitoring and public awareness efforts seem to have prevented milfoil incursions for the present.

The report noted that an invasive animal species, the "Chinese Mystery Snail," has been documented in all four of Norway's lakes, although they have not been detected in Sand Pond for the last two years.

The snail is large, dark green, and "offensive to the nose" when they wash up on shorelines, according to the report.