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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), collect monthly water samples during the summer to measure the chemical, physical and bacteriological characteristics of the Lake. Samples are sent to DES's limnology labs for analysis. Results are then distributed to each participating lake organization and are used by the DES staff to create an 'Annual Report' for each water bodySee the 2020 and 2019 reports below.  

Where are samples taken and is what being measured? 

Spofford Lake samples are taken at 24 locations:  the deep spot, streams flowing into the Lake, beaches, and at the outlet/dam.  The samples measure total phosphorus, chloride, chlorophyll-a, pH, turbidity, conductivity, acid neutralizing capacity (ANC), water clarity and bacteria (E. coli).

For how many years have these tests been done?

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 equipment in 2020.  

What are the 2020 results?

Based on water samples taken in June and August by SLA volunteers, the report compares Spofford Lake's chemical and physical characteristics with other similar NH Lakes. Please refer to the accompanying "How to read your report' also below. 

Under 'Recommended Actions', the report states: 

Lake water Quality is representative of oligotrophic, or high-quality conditions and the improving chlorophyll levels (algal growth) are encouraging. However, the lake experienced benthic mats of cyanobacteria that surfaced in the fall resulting in a cyanobacteria advisory being issued."

Chemical characteristics: Phosphorus, Chlorophyll-a and E.coli levels are “Good, Very Good & Good," respectively. Conversely, pH and Dissolved Oxygen (DO) levels are “Slightly Bad & Bad.”  This is unusual as these measurements generally move together. 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: “may indicate pollution from such sources as road salting (and) septic systems...”

What were the 2019 results?

"Lake water Quality is representative of oligotrophic, or high-quality conditions and the improving chlorophyll levels (algal growth) are encouraging. However, water quality in many tributaries to the lake is representative of poor condition, particularly following storm events.  Assess areas prone to stormwater runoff and implement stormwater best practices to divert and infiltrate stormwater prior to reaching tributaries and the lake….

Chemical characteristics: Phosphorus, Chlorophyll-a and E. coli levels are “Good, Very Good & Good” respectively. Conversely, pH and Dissolved Oxygen (DO) levels are “Slightly Bad & Bad”. This is unusual as these measurements generally move together. 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: “may indicate pollution from such sources as road salting (and) septic systems...”  “Chloride levels in Rt. 63 #3 exceeded the state chronic chloride standard.” 

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:

     adopt “anti-runoff” practices outlined in "Soak Up the Rain" and 

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

     use “lake friendly” cleaning and lawn products

Page updated April 20, 2021






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Spofford Lake Association

PO Box 177
Spofford, NH 03462

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