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Accessible Watershed Information

For assistance in reading or understanding the information on this page, call us at (800) 553-5191.

Return to the non-accessible, interactive map

Monitoring Sites

Nine tributary locations have been continuously monitored for flow and total phosphorus since 2007. Flow monitoring is performed to obtain an overall understanding of how streams, rivers, and ponds respond to precipitation throughout the watershed. Total phosphorus monitoring is performed because it is a key pollutant that can lead to excess algal growth. Total phosphorus monitoring is also performed at five in-pond locations to evaluate the water supply`s response to the phosphorus loads from the watershed. Groundwater monitoring for total phosphorus at the nine tributary sampling locations or nearby began in 2013 to help determine phosphorus loads coming from groundwater baseflow versus from stormwater runoff. These monitoring sites are shown on this layer with graphs of tributary phosphorus, groundwater phosphorus, and/or flow data.

In Pond Sites:

Sampling Location: 08-PEN
Pond: Bowers Pond
Subwatershed: Pennichuck Brook to Bowers Pond


Sampling Location: 07P-PEN
Pond: Bowers Pond
Subwatershed: Pennichuck Brook to Supply Pond


Sampling Location: 07F-PEN
Pond: Bowers Pond
Subwatershed: Pennichuck Brook to Supply Pond


Sampling Location: 06-PEN
Pond: Harris Pond
Subwatershed: Pennichuck Brook to Supply Pond


Sampling Location: 04-PEN
Pond: Harris Pond
Subwatershed: Pennichuck Brook to Supply Pond

Additional Sites:

Witches Brook Monitoring SiteSampling Location: 01-HAY
Tributary: Witches Brook
Subwatershed: Witches Brook South


02-wchSampling Location: 02-WCH
Tributary: Witches Brook
Subwatershed: Witches Brook South


Witches Brook East monitoring siteSampling Location: 01-XWB
Tributary: Unnamed Tributary to Witches Brook
Subwatershed: Witches Brook East


12-penSampling Location: 12-PEN
Tributary: Pennichuck Brook
Subwatershed: Pennichuck Brook to Pennichuck Pond


01-wchSampling Location: 01-WCH
Tributary: Witches Brook
Subwatershed: Witches Brook East


Stump Pond Brook monitoring siteSampling Location: 09-XPB
Tributary: Unnamed Tributary to Pennichuck Brook
Subwatershed: Stump Pond Brook


Stump Pond Brook monitoring siteSampling Location: 01-CML
Tributary: Unnamed Tributary to Pennichuck Brook
Subwatershed: Stump Pond Brook


01-mudSampling Location: 01-MUD
Tributary: Muddy Brook
Subwatershed: Muddy Brook


09t-penSampling Location: 09T-PEN
Tributary: Pennichuck Brook
Subwatershed: Pennichuck Brook to Holts Pond


09-penSampling Location: 09-PEN
Tributary: Pennichuck Brook
Subwatershed: Pennichuck Brook to Bowers Pond


01-bfbSampling Location: 01-BFB
Tributary: Pennichuck Brook
Subwatershed: Boire Field Brook


Best Management Practices

Parts of the Pennichuck Watershed contain some of the most developed land in the state, much of which was developed between 1960 and 1990, before best management practices (BMPs) to treat water quality were required or used.  To address the challenge of existing pollution, Pennichuck has been involved in the design, construction, and continued maintenance of several stormwater BMPs within the watershed.  This layer identifies the location of these BMPs and also provides a photo and description of each.

Pennichuck Square

Site Name: Pennichuck Square
BMP Type: Low Impact Development / Infiltration
Tributary: Pennichuck Brook
Subwatershed: Pennichuck Brook to Holts Pond
Town: Merrimack
Pollutants Addressed: Total Suspended Solids, Nitrogen, Phosphorous, Metals
Pennichuck Square Q&A (opens in pdf 35 KB)
Press release about Pennichuck Square (opens in pdf 35 KB)
Case Study on Low Impact Development (opens in pdf 222 KB)


Celina Avenue

Site Name: Celina Avenue
BMP Type: Sediment Trap and Swale
Tributary: Pennichuck Brook
Subwatershed: Pennichuck Brook to Holts Pond
Town: Nashua
Pollutants Addressed: Total Suspended Solids, Nitrogen, Phosphorous


Cornerstone Site

Site Name: Cornerstone Site
BMP Type: Detention Basin
Tributary: Boire Field Brook
Subwatershed: Boire Field Brook
Town: Nashua
Pollutants Addressed: Nitrogen, Phosphorous, Metals


Tinker Road

Site Name: Tinker Road
BMP Type: Wet Pond, Wetlands & Filter Berm
Tributary: Pennichuck Brook
Subwatershed: Pennichuck Brook to Supply Pond
Town: Nashua
Pollutants Addressed: Total Suspended Solids, Nitrogen, Phosphorous, Metals, Pathogens


Pennichuck Wet Pond at Community College

Site Name: Nashua Community Technical College
BMP Type: Wet Detention Pond
Tributary: Pennichuck Brook
Subwatershed: Pennichuck Brook to Bowers Pond
Town: Nashua
Pollutants Addressed: Total Suspended Solids, Nitrogen, Phosphorous, Metals, Pathogens

For assistance in reading or understanding the information on this page, call us at (800) 553-5191.

Return to the non-accessible, interactive map

Follow this link to download Microsoft excel spread sheets that contain the raw data which was used to create the non-accessible interactive map.  This also includes non-accessible charts for flow and phosphorous levels