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Lake Water Quality

What is the SLA's Water Quality Testing Program? 

SLA’s Water Quality Testing team, in conjunction with NH DES' Volunteer Lake Assessment Program (VLAP), collects water samples between May and September to measure the chemical, physical and bacteriological characteristics of the Lake. Samples are sent to DES's limnology labs for analysis and an 'Annual Report' is prepared.  See the adjacent 2021 report.  

The SLA has had an active water quality testing program for some 20 years.  Water quality, being such an important barometer of lake health, SLA invested in its own measuring dissolved oxygen and temperature measuring equipment in 2020.  

Where are samples taken and is what being measured? 

In 2022, water quality testing is being expanded as part of the Town's Watershed Committee's efforts to create a more detailed understanding of the Lake's physical and chemical profile. Water samples will be taken at 31 locations (rather than the typical 25) surrounding and on the Lake including:  the deep spot11 inlets  (where ‘streams’ flow into the Lake), 7 beaches, the boat ramp, and the outlet/dam.  Several up-stream locations will also be tested in 2022. 

Fourteen water quality parameters are to be sampled during each sampling event. These are: Dissolved Oxygen and Water Temperature by meter, Color, Chloride, E. coli bacteria, Acid Neutralizing Capacity, pH, Alkalinity, Total phosphorous, Water clarity (via Secchi disk), Conductivity, and Turbidity, Total Nitrogen, Organic Carbon and Phytoplankton.  

What are the 2021 results?

Based on water samples taken in June, July and August by SLA volunteers, the VLAP report for 2021 (issued in early 2022), the report states: 

Lake Water Quality is representative of oligotrophic, or high-quality conditions: pH, Chlorophyll-a, transparency and phosphorus levels are stable. Conductivity is worsening. As you know, the lake experienced benthic mats of cyanobacteria that surfaced in the fall of 2020  resulting in a cyanobacteria advisory being issued.

Chemical characteristics: Phosphorus and Chlorophyll-a are within the acceptable thresholds as defined by NH DES. Dissolved Oxygen (DO) levels fall quickly below 12 meters during July and August. DO levels and temperature patterns "influence lake productivity, physical properties, phosphorus cycling and fish and aquatic animal populations." Main causes of low DO are increasing amounts of decaying organic matter from stormwater runoff and eroding shoreline.

Conductivity: Levels are greater than the historic median conductivity levels of NH Lakes. 

 What can I as a homeowner do to help?

Take time to understand the Lake's vulnerabilities and think about what steps you might take to maintain and improve Spofford Lake's water quality.  Be aware that the SLA-funded Watershed Management Plan and the SLA-funded Core Sediment Analysis provide greater context to the VLAP reports.  

Also consider implementing practices to minimize runoff from your property, for example:

•  make sure that you have a well functioning septic systems and that it is pumped out regularly     

     refrain from adding sand to beaches, as this only encourages plant growth and resulting decay

     use “lake friendly” cleaning and lawn products

Page updated May 17, 2022

Useful Downloadable PDF

Spofford Lake 2021 VLAP Report


Spofford Lake Association

PO Box 177
Spofford, NH 03462

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