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Reducing Runoff, Especially Phosphorus

Why is phosphorus so important?

Phosphorus is a naturally occurring and essential nutrient for both plant and animal growth. Phosphorus is found in the soil, animal manure, most fertilizers, storm water runoff and human waste products. It is often found to be the plant growth-limiting nutrient in lakes. If phosphorous is unavailable or in low amounts, plant growth in aquatic systems will stay in check. Once it is freely available, plants can grow to excessive levels. This potentially severe increase in plant growth (algae and rooted plants) is usually associated with a condition known as 'eutrophication,' which eventually leads to declining water quality.

Again, what is eutrophication? 

According to the Oxford Dictionaries, eutrophication is “excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen.”  The process of decay can deplete the water of oxygen and may give rise to algal blooms and reduction of fish species.

Spofford Lake exhibits three characteristics of eutrophication: oxygen impairment, the reduction in fish stocks and, if not an algae bloom, the appearance of cyanobacteria in 2020.

How does phosphorus contribute to eutrophication?

Phosphorus entering lakes and other waterbodies will accumulate in the sediments. When eroded soil enters the Lake, both phosphorus and the nitrogen that is released from the soil contribute to eutrophication.  The Spofford Lake Watershed Management Plan estimated total phosphorous loading by source to be: 50% watershed, 25% atmospheric, 15% septic systems (likely underestimated), 6% internal loading, and 4% waterfowl. 

What can be done to reduce phosphorus levels in the Lake? 

We must work to manage: 1) stormwater runoff, 2) eliminate shoreline erosion and 3) curtail household runoff into the Lake.  Moreover, we must eliminate the introduction of new sand to beaches as this sand may contain unwanted nutrients, like phosphorous.  To the extent not already done, eliminate the use of phosphates in fertilizers and household products. 

What is the SLA doing to reduce runoff into the Lake?

SLA has sought out NH DES 319 runoff grants.  The first grant was obtained in 2019 and addressed issues at larger properties e.g., Camp Spofford, the Spofford Yacht Club, B&K Club, Family Rec Beach, and a number of private residences.  

After a very positive first experience, the second grant application will address runoff from Route 9 at and around the boat ramp and several private properties.  Approval of the second grant is pending, though expected in late 2021 or early 2022.  

As a prerequisite, the Spofford Lake Watershed Management Plan (WMP) was completed in 2018, under the auspices of a 604(b) grant offered by U.S. EPA Clean Water Act.  With the WMP done, 319 runoff grants became possible.

How do these grants work? 

NH DES offers grants as part of its Watershed Assistance Program (WAP).  Known as Section 319 or 319 grants, the State solicits projects to address “nonpoint source pollution (NSP)” through the implementation of watershed-based plans in priority watersheds. Projects must have a measurable way to assess progress and determine success.  

The watershed-based plan must have a clear water quality goal and meet EPA requirements.  Funded grants must make reasonable progress toward achieving the water quality goal established in the watershed plan.  

By design, grants are administered by third-party organizations.  For SLA, the Southwest Regional Planning Commission fulfills that role.  

How were candidate properties chosen?

Properties were chosen by Dover NH-based FB Environmental Associates (FBE) after an analysis of estimated stormwater runoff of all lake shore properties. FBE then visited nine properties in early 2020 to produce a specific plan for each location.  As of this writing, two projects are complete with the remaining scheduled to be completed in 2021.

The total project is valued at $133,333 of which the grant provides $80,000 (60%) in financial support, i.e., for consultants and remediation materials. The remaining 40% or $53,333 comprises volunteer time or expenses related to 'improving the water quality of Spofford Lake'. 

What can I do to minimize runoff from my property?

Reach out to the SLA to see if your property might be eligible for grant subsidies. 

Consider implementing projects offered in "Soak Up the Rain" a free guide authored by NH DES.  The NH LAKES Association has developed another free program called Lake Smart. offering tips and strategies, along with service providers versed in minimizing runoff. 

Page updated October 5, 2021




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Spofford Lake Association

PO Box 177
Spofford, NH 03462

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