A Plan for Our Watershed

How many of us live in a watershed?

It’s a trick question, of course. Everyone lives in a watershed – which can be thought of as a land basin that collects rainfall and snowmelt and then directs it to a lower-lying body of water such as a marsh, lake, or river.

In the case of Lake Wentworth and Crescent Lake, much of the land area in the town of Wolfeboro, including the highlands in the north and east, makes up their watershed. The water that collects in this basin flows into the two lakes by way of numerous streams (see the accompanying map) and through underground seepage.

Very likely, most of us live in a number of watersheds, each of which may empty into a larger one until the water that those watersheds capture makes its way into the ocean.

Lake Wentworth/Crescent Lake subwatersheds
Lake Wentworth/Crescent Lake subwatersheds

For example, residents of Wolfeboro also live in the Lake Winnipesaukee watershed (Wentworth and Crescent empty into the Big Lake) as well as the Merrimack River watershed (where Winnipesaukee’s waters eventually end up).

On a smaller scale, we may live in a localized watershed. For example, people living in the northern parts of Wolfeboro may live in the Fernald Brook, Willey Brook, or Claypit Brook watersheds, while those living in the southeastern parts of town are likely to live in the Warren Brook, Townsend Brook, or Heath Brook watersheds. When viewed from the perspective of the larger watershed into which they drain – in this case, Lake Wentworth – these smaller drainage areas are referred to as sub-watersheds. (By extension, the drainage area of Lake Wentworth and Crescent Lake is a sub-watershed of Lake Winnipesaukee.)

While most of us understand that we need to protect the quality of the water in our lakes, we may not appreciate the fact that the  best way to do that is to look at what is happening to all the water captured in the lake’s watershed rather than focusing on the lake in isolation.

For example, we may find milfoil choking the shallows of one or more brooks that flow into a lake. Clearing the milfoil – an expensive and labor-intensive process — may solve the problem for a season, but why do the weeds grow so extravagantly year after year?

Similarly, we may observe slimy algae blooms lining the shallows along our shorelines during the height of summer. While the unsightly clouds eventually dissipate with cooler weather, we may wonder whether their appearance, which spoils enjoyment of the lake during a prime recreational period, is really unavoidable.

Lastly, maybe we see extensive sandbars at the mouths of major streams, creating navigational hazards along the shorelines and limiting access to properties farther upstream, and it may occur to us that these obstacles appear to be growing.

The broader view

While it may be possible, with more or less success, to tackle each of these issues individually, a broader perspective will likely reveal some common sources for these problems. Identifying — and eventually tackling — those underlying sources requires a coordinated effort.

That effort most commonly takes the form of a management plan that evaluates the entire watershed.

Both the federal Environmental Protection Agency (EPA) and the New Hampshire Department of Environmental Services have identified watershed-level planning as the most appropriate basis for managing and protecting water resources. A watershed management plan (WMP) can be used to provide much-needed information about the health of the streams that feed a lake, the condition of wetlands that absorb and filter storm flows, and the location of high-value habitats that provide food and shelter for a variety of bird and animal species.

A management plan can also identify actual and potential sources of unwanted nutrients and other pollutants entering the waters that feed a lake. Those nutrients encourage the growth of weeds, such as invasive milfoil, as well as algae blooms that are both unsightly and, in the case of blue-green algae, potentially dangerous.

All this information then provides a solid foundation for decision-making in the management of a community’s surface water resources and the mitigation of threats to those waters.

The issues cataloged earlier – persistent milfoil infestation, algae blooms, and growing sandbars – are all readily identifiable in Lake Wentworth and Crescent Lake. In response, a number of collaborating groups  – including the Lake Wentworth Foundation , the Town of Wolfeboro Planning Department, and the University of New Hampshire –  have secured a grant from the New Hampshire Department of Environmental Services (DES) to develop a management plan for the Lake Wentworth/Crescent Lake watershed. The effort is scheduled to begin over the coming summer and end in December 2013.

The Lake Wentworth Foundation has committed up to $30,000 to match some $67,800 from the EPA/DES grant. In addition, in-kind services and volunteer work from the community are expected to contribute upwards of $60,000 in match.

The project is expected to deliver a plan that will identify threats and potential threats to water quality in the watershed, as well as identifying high-value natural resources that deserve protection.

Scope of the plan

As in many watersheds with extensive development, the source of many of the problems appearing in Lake Wentworth and Crescent Lake can be traced back to excessive phosphorous and its principal mode of transport: stormwater runoff.

Stormwater runoff is the uncontrolled flow of water and debris that is seen during heavy rainstorms. It’s stormwater runoff that carries sand and other material from disturbed land, from poorly graded roads, and from barren yard areas and sends that debris into brooks that eventually empty into wetlands and the lakes themselves. There, the sand not only releases its phosphorous into the water but ends up choking the receiving marshes and the mouths of brooks that feed the lakes.

It’s the phosphorous carried by stormwater runoff that nourishes weeds such as milfoil and that provides essential nutrients for algae blooms.

The scope of the project

Not unexpectedly, it’s stormwater runoff and its accompanying phosphorous that are the main targets of the Wentworth/Crescent watershed management plan. To the extent that runoff can be kept in check, the wetlands, streams, and lakes in the watershed will preserve the water quality that makes them so attractive. To the extent that uncontrolled runoff continues to load our waters with phosphorous, we can expect to see a continued degradation in water quality as our lakes turn increasingly green with algae and weeds.

The Wentworth/Crescent WMP comprises almost a dozen measurable objectives, many of them requiring precise collection and analysis of data. Among those objectives are:

  • Assembling current water quality data, including 25-plus years of Lakes Lay Monitoring Program results, into a database to establish a current baseline of information
  • Establishing a water quality target for the future
  • Identifying current and future pollution sources
  • Estimating pollution reductions needed to maintain the water quality target
  • Determining the actions needed to achieve pollution reductions
  • Recommending land use adjustments that may be needed to achieve the targeted water quality
  • Reviewing town zoning and planning ordinances and regulations that can have an impact on lake water quality and provide recommendations for changes.
  • Providing education to people living in the watershed regarding their role in protecting water quality now and in the future

As part of both the data gathering and educational outreach efforts, a major survey was conducted of property owners along the lake shores and feeder streams. The effort was aimed at ascertaining the public’s understanding of pollution issues as well as the ability of various soils in the watershed to mitigate the impact of septic systems on water resources. The eight-week canvass, which took place in the summer of 2011, also distributed informative brochures describing how to care for septic systems and how to use native plant species to prevent stormwater runoff from shoreline properties.

The bigger picture

The Wentworth/Crescent watershed management plan complements the Town of Wolfeboro’s existing Master Plan and provides additional guidance to planners, developers, and others in managing the town’s future growth.  In addition, the Wentworth/Crescent WMP will eventually integrate with an ongoing effort to create a management plan for the entire Lake Winnipesaukee watershed. That project started in 2008 with a localized WMP for the northwestern shores of the Big Lake, including Meredith Bay. Next, the effort is moving to Center Harbor and Moultonborough, then Tuftonboro and, eventually, Wolfeboro Bay.

The Wentworth Crescent WMP effort is one of several similar projects across the state splitting some $500,000 in funding from the US Environmental Protection Agency under Section 319 of the Clean Water Act.

Completion of a watershed plan has qualified the Town and the Foundation to apply in future years for additional money to control specific pollution sources.

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