Version 1.09, July 12, 2012
Adapted from the NH Residential Loading Model spreadsheet available from NH Department of Environmental Services

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Phosphorus ("P") is a naturally occurring element and a major nutrient required for biological productivity. It is found in all living plants and animals, including people.

Human impact on the environment can cause increased levels of P from several sources including runoff and fertilizer use. Development and land use change, including the creation of impervious cover (parking lots and roads) can limit natural ground filtration and cause an increase of P in freshwater.

Cyanobacteria bloom
Bear Island, Lake Winnipesaukee, June 2011

Increased P levels in freshwater, along with other environmental conditions may result in increased biological productivity, which can cause:
  • Decreased water clarity
  • Increased chlorophyll a levels
  • Increased turbidity levels
  • Accelerated lake eutrophication
  • Decreased oxygen concentrations
  • Undesirable shifts in relative abundance of aquatic species

The Lake Winnipesaukee Watershed Management plan has identified limiting the P load as a key goal for overall lake health.

So, how can you help? Use the NEW HAMPSHIRE RESIDENTIAL LOADING MODEL tool to determine your P load on the Lake.

This tool will allow users to calculate their current Phosphorus runoff, and determine the impact of changes such as new construction, land use changes, or implementation of new stormwater treatment practices.

This tool will guide you through the following steps:

  1. Enter Your Site Conditions, including location, land use (current and planned) and annual fertilizer use
  2. Input Current Stormwater Treatment Practices used, such as Rain Barrels, Dry Wells, Filtration, etc.
  3. Input any Planned Stormwater Treatment Practices, for comparison
  4. Review the results, and determine whether any planned changes will reach P reduction goals

Get Started!

For more information on Phosphorus, please click here (PDF 1.1mb)

What's your P? application developed by GreenInfo Network and Applied Geographics, in partnership with the Lake Winnipesaukee Watershed Association and NH Department of Environmental Services.