Water Quality 2019-04-25T13:56:30-04:00

Water Quality

Photo by Pen Hallowell

Based on the current and historical water quality data, Chocorua Lake is considered an unproductive “pristine” New Hampshire lake that at times borders conditions typical of a more nutrient enriched, mesotrophic lake. While the current Chocorua Lake water quality is high, developmental pressures within the Chocorua Lake watershed continue to pose a threat to the lake.

2018 a Banner Year for the Water Quality in Chocorua Lake!

Ten sampling events were accomplished throughout the summer of 2018. On each of these ten days, a Secchi Disk measurement was made to determine the water-column clarity, a profile of the change in water temperature with depth was determined and a series of water-quality parameters were measured in the laboratory. The work was done in conjunction with the University of New Hampshire’s Lake Lay Monitoring Program (LLMP).

A summary of the findings for 2018 can be found below. But in short, the water quality of Chocorua Lake this past year was outstanding with the average for water clarity, chlorophyl-a, and total phosphorus falling within the “oligotrophic/excellent” range for fresh water lakes in New Hampshire. The water was slightly tea colored, was moderately vulnerable to acid precipitation, had an optimal acidity (pH) for fish growth and reproduction and had a low total-disssolved-solids concentration.

Click here for full 2018 water quality testing results.

Chocorua Lake is an oligotrophic lake.  Oligotrophic lakes are pristine and ideal for swimming and trout fishing. Such lakes are characterized by high water clarity, low nutrient concentrations (phosphorus and nitrogen), minimal levels of aquatic plant growth (weeds), and low algae concentrations. In oligotrophic lakes, oxygen is found at high levels throughout the water column. In addition, low algal concentration allows deeper light penetration and less decomposition. When algae, zooplankton and fish die, they sink to the bottom and are decomposed by microbes and invertebrates. This decomposition process uses up oxygen. Since oligotrophic lakes are less fertile and have less algae and other organisms, there is less decomposition and the oxygen doesn’t get used up.  The fish found in oligotrophic lakes like cold, high oxygenated water, such as rainbow trout.

It is important to remember that lake trophic state is not interchangeable with water quality. Water quality is subjective and depends on how you intend to use the water body. A lake that is good for duck hunting is not necessarily good for water skiing. In turn, a lake that is great for swimming may not be great for bass fishing.  For more about the life cycle of lakes, and what makes Chocorua an oligotrophic lake, see see the Fall/Winter 2015 CLC Newsletter.


Funding for the Chocorua Lake water quality monitoring program is provided by the Conservancy. The Chocorua Lake Conservancy has been participating in the New Hampshire Lakes Lay Monitoring Program since 1981.  The New Hampshire Lakes Lay Monitoring Program is jointly administered through the UNH Cooperative Extension Natural Resources Program Team and the Center for Freshwater Biology at the University of New Hampshire. For a history of the CLC’s water quality testing program in Chocorua Lake, see see the Spring/Summer 2015 CLC Newsletter.


To support the Conservancy’s efforts to preserve the Chocorua Lake Basin and provide public access to the lake for visitors, please click HERE.