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NJDEP Ambient Lake Monitoring Network

map of Lakes sampling sites
Great Gorge Lake,    	Vernon Twp, Sussex County, Fall 07

Network Description

NJDEP initiated, in 2005, a renewed ambient lake monitoring network designed to provide the water quality data necessary to assess the ecological health of the State's lentic water resource. This program involves the testing of randomly selected lakes from the state's approximately 870 named lakes. The water quality measurements conducted at each lake includes parameters such as dissolved oxygen, pH, nutrients, and chlorophyll a. Such testing will assist New Jersey in determining the status and trends in lake water quality, as needed to meet our Clean Water Act requirements and our Total Maximum Daily Load (TMDL)-related water quality assessment obligations.

Water Monitoring & Standards, Bureau of Freshwater & Biological Monitoring has worked to develop a monitoring program that would address both the deficiencies cited in the 1999 USEPA's Office of Inspector General's Audit Report, and the needs of the watershed management and water quality assessment (305(b)/303(d)) programs. This approach comports with the guidance provided in USEPA's publication, "Elements of a State Water Monitoring and Assessment Program," March 2003, which requires that states develop and implement long-term strategies which include monitoring of all state waterbody types, including lakes.

The lake monitoring network design is as follows:

  1. Target Population: All lakes, man-made or natural, excepting water supply reservoirs, wholly or partially within the State of NJ political boundaries. A lake is defined as a permanent body of water of at least two hectares in surface, and a minimum depth of one meter. Lakes were selected randomly, using the USEPA - Generalized Random Tessellation Stratified (GRTS) survey design, but in a manner that equalizes selections over all Omernik level III ecoregions (6 within state). The New Jersey GIS coverage containing approximately 870 named lakes, meeting the design criteria, was used for the selection process.
  2. Network Stations: The network consists of 200 lakes, each sampled once every five years, with forty lakes sampled per year. Depending on the lake size and characteristics, up to four sampling locations will be monitored in each lake. Lakes not exhibiting temperature stratification will be sampled at one meter below the surface, unless the lake is too shallow, in which case the sample will be taken at a depth of one-foot below the surface. Lakes exhibiting stratification will be sampled above and below the thermocline. Depth to bottom will be measured at each station (see below for list of 40 lakes to be sampled this year).
  3. Sampling Frequency: All lakes in the network will be sampled once every five years, with each lake being sampled twice during the year (growing and non-growing season).
  4. Monitoring Parameters: Total Phosphorus, Total Kjeldahl Nitrogen, Total Nitrite+Nitrate Nitrogen, Ammonia Nitrogen, Dissolved Oxygen, pH, Temperature, Specific Conductance, Alkalinity, Hardness, Secchi depths, and Chlorophyll a will be collected and analyzed at each station. Qualitative evaluations of algal blooms and aquatic vegetation will be performed at each lake.
  5. Schedule:
    • Probabilistic selection of network lakes completed by USEPA-ORD and list of 200 candidates, plus extra for alternates chosen.
    • All of the monitoring data collected for this network will be uploaded into the national USEPA STORET/WQX data base.
    • Panel 1, (1st group of forty lakes) completed (2005).       Report now available.
    • Panel 2, (2nd group of forty lakes) completed (2006).      Report now available.
    • Panel 3, (3rd group of forty lakes) completed (2007).       Report now available.
    • Panel 4, (4th group of forty lakes) completed (2008).       Report now available.
    • Panel 5 (5th group of forty lakes) completed (2009).        Report now available.
    • Panel 1, Round 2 (1st group of forty lakes, second Round of sampling) completed (2010).      
    • Panel 2, Round 2 (2nd group of forty lakes, second Round of sampling) completed (2011).      
    • Panel 3, Round 2 (3rd group of forty lakes, second Round of sampling) completed (2012).      
    • Panel 4, Round 2 (4th group of forty lakes, second Round of sampling) completed (2013).      
    • Panel 5, Round 2 (5th group of forty lakes, second Round of sampling) completed (2014).      
    • Spring 2015, sampling scheduled to be initiated.
    • Comprehensive scientific reports, in which lake monitoring results will be discussed and interpreted, will be generated; including an assessment of the trophic state of the lakes sampled. A report will be issued for each Panel of lakes (one monitoring year) after sampling and data review are completed.


For additional information, please contact Johannus Franken at 609-292-0427.


This ambient lakes monitoring project is part of a larger effort in the department to develop current water quality information on this vital water resource.


PLEASE NOTE: This Bureau performs ambient lake monitoring only. For other lake or dam-related inquiries, see below:

[ link to EPA's Monthly Lakes Tips ]

Ambient Lake Monitoring Sites (2015)
[ to be determined ]

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Department of Environmental Protection
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Last Updated: May 5, 2015

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