The septic and stormwater surveys: What did we learn?

NOTE: The following article summarizes a report on the 2011 septic and stormwater surveys prepared by the consulting firm Forrest Bell Environmental for the Steering Committee of the Lake Wentworth/Crescent Lake Watershed Management Plan. A full copy of the consultants’ report, complete with photos, is available on this web site at:

As the summer of 2011 neared its end, a score of dedicated Lake Wentworth Association shore representatives fanned out along the camp roads distributing notices of an upcoming survey that would invite property owners around Lake Wentworth and Crescent Lake to share information about their homes – all this in the interest of supporting the development of a management plan for the watershed that surrounds both lakes.

In the weeks that followed the notification, those same shore reps revisited their neighbors, this time accompanied by environmental consultants gathering data about the location and age of residential septic systems. With the owner’s permission, the consultants also evaluated each property for signs of erosion and other damaging effects from runoff into the nearby lake or stream.

Threats to the water quality of the two lakes had been previously identified in a diagnostic study undertaken by NH Department of Environmental Services (DES) in 1999, and the study had recommended that a sanitary survey be conducted in order to better understand the role that septic systems may have in determining the water quality of the lakes.

That understanding is important because a failing septic system can be detrimental to human health, aquatic life, and water resources. Septic system effluent typically stores a thousand times the concentration of phosphorus typically found in lake waters, which means that even a small amount of effluent can have a major impact on nearby waters.

In addition, an outdated or improperly maintained septic system can result in the delivery of disease-causing bacteria and nutrients to nearby water bodies, causing gastro-intestinal illness in swimmers or severe ecosystem dysfunction for fish and wildlife. Untreated septic waste can also contain chemicals and hormones used in pharmaceutical and personal care products, which can have severe impacts on aquatic life.

Now, a dozen years after the diagnostic study, the Lake Wentworth Foundation has partnered with the Town of Wolfeboro, DES, and the University of New Hampshire to develop a management plan for the entire Lake Wentworth/Crescent Lake watershed. When completed sometime in the fall of this year, the plan will have identified current and potential threats to the surface waters that feed and make up the two lakes. The hope is that, in subsequent years, funding will be found to begin chipping away at the sources of the nutrients that are slowly undermining the health of the lakes and their tributaries.

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LWF offers help in maintaining healthy properties

During the recent survey of properties along the shores of Lake Wentworth and Crescent Lake and their tributaries, volunteers from the Lake Wentworth Foundation distributed informational brochures to help homeowners care for their properties and protect the quality of nearby surface water resources.

In case you didn’t get your set of these helpful brochures, or if you’d like additional copies, you can now download them for viewing and printing.

“Landscaping by the Water” provides advice on the selection, planting, and care of trees, shrubs, and ground covers — most of them native to New Hampshire — that fit settings along a lake shore or stream bank. Not only do these plantings enhance the beauty of a waterside property, but they work well to keep soil in place, helping prevent stormwater runoff that can carry large amounts of phosphorus into the water. Phosphorus acts as a fertilizer for green plants — good for suburban lawns but a source of weed and algae growth when it migrates into a water body.

As an added advantage, use of native plants reduces the amount of care that landscaping requires, since the trees and shrubs naturally thrive in our climate. Continue reading

Gauging the impact of pollutants

If you travel anywhere in Wolfeboro where one of the major tributaries of Lake Wentworth crosses a roadway, chances are good that, over the course of the last six months, you’ve spotted something unusual in the streambed. Poking out of the water is what probably looks like a large white yardstick attached to a fencepost.

Stream gauge

Stream gauge

What you’re seeing is a critical tool in the recently initiated watershed management plan for Lake Wentworth and Crescent Lake – a stream gauge. As the name implies, these gauges, marked in increments of feet and tenths of a foot (rather than inches) measure the height of the water flowing in the stream.

Why is that important? As it turns out, one of the critical aspects of the watershed management plan is getting a handle on how much phosphorous is entering the lakes each year. Phosphorous, you’ll remember, is a plant nutrient that’s great for suburban lawns but highly disruptive to clean lakes like Wentworth and Crescent, because it feeds weeds like milfoil as well as microscopic algae that rob a lake of its clarity.

As it turns out, much of the phosphorous that enters the lakes does so via the streams that feed the lakes. Often, the phosphorous is hitching a ride on sand and other debris washed into the water by runoff from a storm. We’ve all seen the evidence: gravel roads, roadside culverts, and sandy beaches marred by deep trenches where stormwater has eroded the soil and carried it off to a nearby marsh, brook, or even lake.

So how do the stream gauges work? The answer is that, in order to protect a lake, you need to know not only how much phosphorous it currently has but how much is coming in. If, as is the case, with Wentworth and Crescent, a lake is still relatively healthy, you want to know if phosphorous is coming in at a rate that exceeds the lake’s long-term ability to absorb it.

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