2023 LAKE WATER QUALITY SUMMARY

2023 was a year of record-setting weather. Large storms brought upwards of 57 inches of rain to the watershed—washing out roads, flooding homes and sending thousands of tons of sediment into Newfound Lake. Severe storms negatively impact water quality by increasing stormwater pollution which brings sediment, nutrients, and other pollutants to the lake. Newfound’s 38 years of water quality data suggests that the effects of 2023 may linger for some time but don’t necessarily indicate a long-term decline.

INVASIVE SPECIES

Invasive species negatively impact water quality. Lake hosts inspected 2,368 boats in 2023, and Weed Watchers surveyed 100% of Newfound’s near-shore area, finding no invasive aquatic plants. Remember to clean, drain, and dry boats and recreational gear to keep invasive aquatic species out of Newfound. Learn more about invasive species prevention.

WATER QUALITY TARGETS FOR NEWFOUND LAKE

Newfound Lake has excellent water quality. Current state-wide standards defining high water quality in lakes do little to guide the active stewardship of Newfound because even on a bad day, Newfound’s water quality is better than many lakes on their best. In partnerships with representatives from NH Department of Environmental Services and the University of New Hampshire, as well as community volunteers, NLRA has developed a new set of water quality targets specific to Newfound Lake. Clear goals for indicators of lake health allow us to evaluate the success of conservation efforts and inform future conservation plans. Read the full Water Quality Target Report.

VIEW LATEST CONDITIONS AND EXPLORE SEASONAL TRENDS

Newfound Lake’s water quality is measured weekly from mid-May through September at seven monitoring sites. Water quality monitoring is made possible by volunteers and support from organizational partners. Learn more about volunteering.

UNDERSTANDING CURRENT CONDITIONS

Measuring Water Clarity

To measure water clarity, a black and white Secchi Disk is lowered into the water and the depths at which it can no longer be seen is recorded. Clarity is affected by sediment, algae, and plankton in the water column. Deeper water clarity readings indicate better water quality.

The Importance of Surface Temperature

Surface temperature tells us more than whether we should go swimming or not.  When the surface water warms it alters the growth rate of algae and changes the chemistry of the upper layer of the lake.  Seasonal changes are a normal occurrence, but cooler temperatures are generally healthier for the lake.

What is a Thermocline?

If you ever jumped into Newfound and dived deeper than a few feet, you’ve likely noticed a layer where the water temperature changes rapidly. This area is known as the thermocline and is the boundary between the warmer surface layer, called the epilimnion, and the cooler denser water of the hypolimnion. Most of Newfound’s algae and plankton thrive in the warm water layer, while most fish species tend to prefer oxygen-rich cool water, with very little mixing between the top and bottom layers.

LONG-TERM TRENDS

Newfound’s centrally located deepest point best represents lake-wide trends in water quality. We carefully assess data from the “Deep Site”  for long-term trends to understand what’s happening in the entire lake over time.           

Use the dropdown and slider arrows to explore trends. 

WATER CLARITY

Interpreting this Figure

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This figure shows individual readings of water clarity (blue dots) taken during the summer from 1978 to the present. The solid black line is a statistically fitted trendline and the grey shading describes how well the trendline fits the data.

Note: in areas with more data, the shading tends to be narrower, indicating a more accurate placement of the trendline.

TOTAL PHOSPHORUS

Why Phosphorus is Important

Phosphorus is the key nutrient controlling the growth of freshwater plants and algae. It occurs naturally in soils, but human activities like applying fertilizers and failing septic systems have a significant contribution. Impervious surfaces associated with development also concentrate stormwater runoff, leading to increased erosion and the transport of phosphorus in soils to the lake. More phosphorus leads to increased algae and decreased water quality.  

CHLOROPHYLL A

A Pigment You Should Know

Chlorophyll a is a light-absorbing pigment naturally found in all green plants and algae that convert the sun’s energy into food through photosynthesis. It is one of the most abundant chemical compounds on earth! Levels below 3.3 parts per billion (ppb) are best for lakes like Newfound.

DRIVERS OF LONG-TERM TRENDS

Historic Declines in Water Quality

Deep Site measurements of transparency, chlorophyll a, and total phosphorus all show signs of declining water quality from the beginning of our record in the mid 1980s through the late 1990s. During this period, we saw an increase in chlorophyll a, total phosphorus, and a 13-foot (3.9 m) decrease in average summer water transparency at the Deep Site, with similar trends observed at other monitoring sites.

While it is often difficult to attribute direct causes of changing water quality in lake systems, the connection between increasing development and declining water quality is well documented in scientific literature. The 1980s saw an increase in development in the watershed and Newfound experienced several major storm events throughout the 1990s, moving sediment and pollution into the lake. Pollution carried in stormwater runoff from developed areas is Newfound’s largest threat.

Slow and Steady Rebound

Throughout the early 2000s we saw a period of steady improvement across the three measures of water quality with clarity and chlorophyll a approaching levels seen in the mid 1980s and total phosphorus decreasing to 4 parts per billion (ppb).

Impact of Intense Storms

The recent water quality record is dominated by the influence of several large storm events, starting with Tropical Storm Irene in 2011 which brought over 8 inches of sustained rain to the watershed. Its damaging flood waters carried sediment and stormwater pollution to Newfound—dropping lake transparency by 80% to just 6.9 feet (2.1 m). Irene’s legacy can clearly be seen in the transparency and chlorophyll records and impacted water quality for at least the next four years.

Building Resilience

NLRA programs and initiatives work to insure clean water by protecting healthy ecosystems through thoughtful stewardship of natural resources at a variety of scales.

WATERSHED PLANNING

A watershed plan is a strategy for achieving water resource goals.  Watershed planning is a community-driven process addressing watershed-wide problems to protect water resources.

Learn more

STORMWATER MANAGEMENT

Stormwater management projects protect the waters of Newfound Lake and its tributaries from pollution while also protecting our roads, homes, and infrastructure from damage and erosion.

Learn more

LAND CONSERVATION

Thoughtful land conservation is the most effective way to protect water quality.  Undeveloped land acts as a filter, stopping pollution before it reaches our waterways.

Learn more

AQUATIC INVASIVE SPECIES MONITORING

NLRA’s volunteer Weed Watchers monitor Newfound Lake for invasive aquatic plants, while the Lake Host program prevents the spread of invasives with complimentary boat checks at Newfound’s public boat launches.

Learn more

EDUCATION AND COMMUNITY ENGAGEMENT

By educating and engaging our community we can ensure a continued tradition of stewardship in the Newfound Watershed.  NLRA offers programs and events for all ages.

See our events