Eel River and Plymouth Harbor Watershed Management

The Eel River is approximately 3.9 miles in length from the headwaters at the cranberry bogs east of Long Pond Road to the mouth at Plymouth Harbor.  Another branch of the river begins south of Forge Pond and continues north past Clifford Road bridge where it connects to the main branch.  The Eel River Watershed is approximately 15 sq.miles and has been delineated based on groundwater modeling, click here for map.  The Eel River Watershed is a valuable natural resource to the Town of Plymouth not only for its natural resources, but for the aesthetic and recreational opportunities it provides for locals and tourists.  This watershed contains approximately 800 acres of open water and is habitat to various fish species and wildlife that create a healthy ecosystem.  

The Eel River outlets into Plymouth Harbor which is a valuable resource for the Town.  Plymouth Harbor offers aesthetic and recreational opportunities to locals and tourists as well as shellfishing resources.  Tourists from all over the world come to visit to explore the history, natural beauty and recreational opportunities Plymouth Harbor has to offer.  Famous historical sites are visited daily such as Plymouth Rock and the Mayflower II.  Recreational activities including whale-watching, swimming, deep-sea fishing, shellfishing, boating and birding are toursit attractions in the Harbor.  Over time, however, Plymouth Harbor has become an impaired waterway listed as 303(d) due to bacterial contamination and nutrient inputs from point and non-point source pollution.  The bacterial contamination had contributed to the prohibition of shellfishing for 40-50 years in Plymouth Harbor.  However, due to the vast work and improvements in water quality approximately 164 acres of shellfishing was opened in 2014 along Long Beach in Plymouth Harbor.

An increase in nitrogen and phosphorus levels can lead to eutrophication which is the over-enrichment of a waterbody with nutrients resulting in excessive plant growth.  This excessive plant growth depletes oxygen levels and can cause organisms including fish to perish.  Nutrients such as, nitrogen & phosphorus, can enter the river system from various sources including stormwater runoff, fertilization and septic systems.

The Town of Plymouth has an obligation to conduct and implement a Nutrient Management Plan per the Wastewater Treatment Facility (WWTP) Permit.   As part of this requirement the Town has been conducting groundwater monitoringsurface water monitoring and biological monitoring in the watershed and within the Eel River.  

USGS Real Time Water Data for Eel River
Route 3A Gauge

Click here for information on MEP Linked Watershed Embayment Nitrogen Threshold Analysis

Annual Nutrient Management Plan Data Reports 
Appendices

Map 1 - Plymouth Harbor & Eel River Watershed
Map 2 - WWTF & Eel River Watershed
Map 3 - Surface Water Sampling Locations
Map 4 - Groundwater Sampling Locations
Map 5 - Biological Monitoring Locations
Appendix A - Surface Water Data Results 1998-2021
Appendix B - Groundwater Data Results 2006-2021
Appendix C - Biological Data Results 2008-2021
Appendix D -Figure II-2 of Technical Advisory Report
Appendix E -Memorandum Nutrient Management Plan Baseline Water Quality Assessment Methods
Appendix F - Surface Water Sampling Standard Operating Procedures
Appendix G - Ground Water Sampling Standard Operating Procedures

Data Report - Operational Monitoring Program Data Report 2021
2021 Report Document
Appendix H - Nutrient Management Plan Laboratory Results 2021 

Data Report - Operational Monitoring Program Data Report 2020
2020 Report Document
Appendix H - Nutrient Management Plan Laboratory Results 2020 

Data Report - Operational Monitoring Program Data Report 2019
2019 Report Document
Appendix H - Nutrient Management Plan Laboratory Results 2019 

Data Report - Operational Monitoring Program Data Report 2018
2018 Report Document
Appendix H - Nutrient Management Plan Laboratory Results 2018 

Data Report - Operational Monitoring Program Data Report 2017
2017 Report Document
Appendix H - Nutrient Management Plan Laboratory Results 2017 

Data Report - Operational Monitoring Program Data Report 2015-2016
2015-2016 Report Document
Appendix H - Nutrient Management Plan Laboratory Results 2015-16 (78MB)

Data Report - Operational Monitoring Program Data Report 2013-2014
2013-2014 Report Document
Appendix H - Nutrient Management Plan Laboratory Results 2013-14 (78MB)

Data Report - Operational Monitoring Program Data Report 2012
2012 Report Document
Appendix H - Nutrient Management Plan Laboratory Results 2012 (48MB)

Data Report - Operational Monitoring Program Data Report 2011

Appendix H - Nutrient Management Plan Laboratory Results 2011 (27MB)

Data Report - Operational Monitoring Program Data Report 2008-2010
2008-2010 Report Document

Appendix H - Nutrient Management Plan Laboratory Results 2008-2010 (20-30MB each)
2006 Lab Results
2007 Lab Results
2008 Lab Results
2009 Lab Results
2010 Lab Results

Data Report - Operational Monitoring Program Data Report 2006-2007 
2006-2007 Report Document

Slimy Sculpin 
Cottus cognatus

 
DEP & the Town of Plymouth, September 2007