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Lake Water Quality Monitoring

What is the SLA's Water Quality Monitoring Program? 

The SLA has had an active water quality monitoring program for over three decades.  The Water Quality Monitoring ( WQM) 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 form the basis of the 2021 Annual Report, see sidebar.  

Where are samples taken and is what being measured? 

In 2022, water quality monitoring is being greatly 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. See the sidebar map for locations.  Click here (May 13 edition) for "Job #1, WaterQuality" and more information on the 2022 testing program.  

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 indicates:  

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 August 1, 2022






Useful PDF Download


Spofford Lake 2021 VLAP Report


2022 Testing Stations




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Spofford Lake Association

PO Box 177
Spofford, NH 03462

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