Lakes Weather Drought

posted Oct 3, 2016, 6:32 PM by Joseph Bickard

The Lakes Region is experiencing mild to moderate drought conditions this summer, prompting fire Departments in Raymond and Bridgton to temporarily cease issuing burn permits and the state to urge residents to conserve water.

But one thing residents don’t have to be concerned about during the drought is its impact on its lakes, experts say.

The Sebago Lake level is monitored and controlled by Sappi North America in consultation with state agencies. Even when rainfall is less than usual, outflows from the lake are controlled in such a way that lake level will not be dramatically different from in previous years.

While lowering the outflow of the lake can affect its health, officials say that careful monitoring of both water levels and dissolved oxygen, an indicator of lake health, has shown Sappi continues to meet the water quality standards established by the state.

In Sebago Lake and the Presumpscot River, water levels are determined by a number of co-occurring factors including climate and municipal water supply, as well as outflow at the Eel Weir Dam in Windham. Dam operations are controlled by Sappi and governed by an Operations and Flow Monitoring Plan developed in accordance with the state and federal licenses, said Brad Goulet, hydro manager and utilities engineer with Sappi.

Due to lack of rain this summer and lack of snowfall earlier this year, Sappi has reduced the level of flow to the minimal allowable amounts to offset the effects of abnormally dry weather, according to Kathy Howatt, hydropower coordinator at the Maine Department of Environmental Protection.

Sappi has consulted with regulating agencies, including the department of environment, in decisions regarding changes to the outflows.

The dam’s flow monitoring plan, written last year, attempts to more closely mimic nature by maintaining slightly higher lake levels (266 feet) in spring and slightly lower levels (262 feet) in summer, said Goulet. The current lake level is approximately 264 feet.

To maintain this level despite dry conditions, outflow from Sebago Lake has occurred at a rate of 270 cubic feet per second, or 174 million gallons of water per day, according to Howatt. The normal summer outflow is significantly higher, 408 cubic feet per second, equivalent to 263 million gallons of water per day.

According to Howatt, Sappi has conducted additional monitoring of dissolved oxygen in the river. Lower levels of dissolved oxygen tend to be found in lakes that are more stagnated and have warmer water temperatures, according to the United States Geological Survey, a scientific agency for the natural sciences.

Levels of dissolved oxygen in the lake are regulated by the state’s water quality standards. According to Howatt, Sappi has continued to meet the minimal allowable level of dissolved oxygen, which is 7 parts per million.

Dissolved oxygen is necessary for plant and animal life, and is generally used as an indicator of lake health. Lower levels of dissolved oxygen can cause the death of aquatic life, according to the geological survey agency.

For many of the region’s other lakes, the lack of rain may actually be beneficial for water quality, according to a scientist from the Lakes Environmental Association.

Scientists from the Lakes Environmental Association say, from casual observation, that the water levels in many of the lakes are lower than usual.

During routine water sampling on the roughly 40 lakes monitored by the association, Pratt said she and her team have come to know the waters and can expect a certain depth. They measure the lowest point in the lake for water sampling.

Another tell-tale sign is exposed lines on rocks around the lake from where water levels typically hit.

Generally, lower lake levels means a higher concentration of dissolved nutrients in the water, such as phosphorous and nitrogen. This means higher concentrations of these nutrients, as well as pollutants, in the lake.

Higher nutrient levels are typically bad news for lakes. Algaes tend to grow in greater abundance in high-nutrient lakes, scumming up the surface of the water.

However, although nutrients and pollutants are in greater concentration when a lake gets little rain, the association is seeing greater clarity on the lakes this year than in previous years.

That’s because in other ways, a lack of rain contributes to less nutrients in the water and therefore clearer lakes. Rain brings loose soil from the shoreline – containing phosphorous – into the water, again contributing to diminishing water quality.

In the case of many of the region’s lakes, most of the phosphorous is carried into the water by storm-water runoff. Few storms means little runoff.

From year to year, whether the amount of nutrients in the lake is increasing depends on the lake, Pratt said. In some lakes, the general trend is that the phosphorous is increasing. In others, it’s chlorophyll – a green pigment found in algae and involved in photosynthesis – that’s increasing. In other lakes, there are no trends, she said.

With the summer barely over and the association still doing regular data collection, it’s too early to say how the lack of rain will fit into the trends on the lakes over time.

For boaters and swimmers, lake levels are a big deal. Pratt said every year lake enthusiasts inquire regularly about lake levels –- some want the water level lower, others higher. She tells them, “be patient, and realize that’s the way nature works.”

From left, Executive Director Peter Lowell, Researcher Amanda Pratt, and Assistant Director Colin Holme of the Lakes Environmental Association set up an automated water monitoring buoy in the north basin of Long Lake last week. The buoy tests for temperature, oxygen levels and chlorophyll, a proxy for algae.