Some of these decisions are EPA's. 9 of these 611 records carry a Clean Water Act cleanup plan EPA established rather than New Jersey. They are counted in every figure on this page, and each record page names which.
State water-quality picture · #15 by reported lake-type waterbodies
New Jersey lakes and reservoirs
Every figure on this page is computed from the assessment decisions New Jersey reported to the U.S. Environmental Protection Agency under Clean Water Act sections 303(d) and 305(b) (reporting cycles 2022), plus daily water-level observations from the U.S. Geological Survey.
- 611
- Reported waterbodies
- 583
- Not supporting a use
- 261
- Fish use not supporting
- 1
- Gauged lake
New Jersey in one line
611 lake-type waterbodies in New Jersey are reported to EPA ATTAINS across reporting cycles 2022: 583 assessed as not supporting at least one designated use, 21 fully supporting, and 7 without a definitive overall verdict. The most-listed impairment cause is Arsenic, on 325 waterbodies.
- 611
- reported waterbodies
- 583
- not supporting a use
- 21
- fully supporting
- 97%
- of definitive verdicts impaired
An unassessed waterbody is neither confirmed clean nor confirmed impaired; states assess on multi-year cycles.
New Jersey's large register still carries a heavy not-supporting share
Among the largest third of state lake-type registers (611 units), New Jersey also sits in the upper third for ruled not-supporting share (97%). The size and the load move together here, not every large inventory does.
Data updated 2026-08-17
According to the U.S. Environmental Protection Agency's ATTAINS program, New Jersey reported 611 lake-type waterbodies in New Jersey in the August 2026 extract. See our methodology for filer attribution and multi-year reporting cycles.
How New Jersey's large inventory splits across overall status
Each of the 611 lake-type units reported by New Jersey lands in exactly one overall-status bucket. On a register this large, the bar is an inventory partition, the cause chart and national gauge below answer different questions.
Most-listed impairment causes in New Jersey
Waterbodies carrying each listed cause, most first
- Arsenic
Arsenic
325 waterbodies
- Escherichia coli (E. coli)
Escherichia coli (E. coli)
308 waterbodies
- Index of Biological Integrity (Ibi)
Index of Biological Integrity (Ibi)
252 waterbodies
- Phosphorus, Total
Phosphorus, Total
210 waterbodies
- Mercury in Fish Tissue
Mercury in Fish Tissue
173 waterbodies
What this shows Arsenic is the most-listed impairment cause in New Jersey, on 325 of the lake-type waterbodies reported there.
Computed share from EPA ATTAINS filed records, not an official EPA rating or safety grade.
New Jersey: 97% of ruled verdicts are not-supporting, against a national share of 53%, 1.8× the national rate.
Reporting practice
Nearly all of New Jersey's inventory carries a definitive verdict
Each reporting authority decides how much of the water it files to EPA it actually assesses in a cycle. That decision sets the denominator behind every count on this page.
New Jersey holds the 15th-largest reported lake-type inventory in the country, 611 assessment units, carrying a definitive verdict on 98.9% of it. The counts above describe the 604 units carrying a verdict, not all 611 reported.
The states reporting at the nearest rates are New Hampshire (99.9%) and Delaware (97.9%).
Assessing more of an inventory is a reporting choice, set by cycle length, monitoring budget and how finely a state splits its waters into units. It is not a measure of water quality, and it is why a raw count from one state does not sit beside a raw count from another. How assessment coverage varies.
New Jersey against every comparable state
Share of reported lake-type waterbodies carrying a definitive verdict
98.9% 4th of 47 higher than 43 of 47 states
the 47 comparable states, by definitive-verdict share
Each bar is a band; taller bars hold more states. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA ATTAINS · Reporting cycles 1987–2026
Each bar counts states whose definitive-verdict share falls in that 10-point band. The 47 states shown are those reporting at least 25 lake-type units; a share off a smaller inventory is precision the data does not have.
By size
Largest assessed lakes in New Jersey
By assessed acreage as reported in ATTAINS. Acreage is the assessed unit's size, which can differ from a lake's full surface area.
| # | Waterbody | Assessed acres |
|---|---|---|
| 1 | Wanaque Reservior (below Monks gage) Not Supporting | 2,599 |
| 2 | Lake Hopatcong Not Supporting | 2,583 |
| 3 | Prescott Brook / Round Valley Reservior Not Supporting | 2,297 |
| 4 | Merrill Creek Not Supporting | 1,298 |
| 5 | Wallkill R / Lake Mohawk(above Sparta Sta) Not Supporting | 975 |
| 6 | Wanaque R/Greenwood Lk(aboveMonks gage) Not Supporting | 881 |
| 7 | Maurice River (Union Lake to Sherman Ave) Not Supporting | 865 |
| 8 | Culvers Creek Not Supporting | 816 |
| 9 | Clinton Reservior/Mossmans Brook Not Supporting | 802 |
| 10 | Rockaway R (Boonton dam to Stony Brook) Not Supporting | 799 |
| 11 | Green Pond Brook (above Burnt Meadow Bk) Fully Supporting | 778 |
| 12 | Hackensack R (Oradell to OldTappan gage) Not Supporting | 737 |
By cause count
Most-listed waterbodies in New Jersey
Waterbodies carrying the most listed impairment causes among the lake-type units reported by New Jersey.
| # | Waterbody | Listed causes |
|---|---|---|
| 1 | Morses Creek / Piles Creek Not Supporting | 13 |
| 1 | Passaic R Lwr (Saddle R to Dundee Dam) Not Supporting | 13 |
| 3 | Branchport Creek Not Supporting | 11 |
| 3 | Cooper River (Rt 130 to Wallworth gage) Not Supporting | 11 |
| 3 | Cooper River (Wallworth gage to Evesham Rd) Not Supporting | 11 |
| 3 | Hackensack R (Amtrak bridge to Rt 3) Not Supporting | 11 |
| 3 | Hackensack R (Ft Lee Rd to Oradell gage) Not Supporting | 11 |
| 3 | Hackensack R (below Amtrak bridge) Not Supporting | 11 |
| 3 | Passaic R Lwr (Second R to Saddle R) Not Supporting | 11 |
| 3 | Passaic R Upr (Pompton R to Pine Bk) Not Supporting | 11 |
Every row in this table ties with at least one other on the ranked value: 2 at 13 (rank 1), 8 at 11 (rank 3). Tied rows share a rank and are listed in no meaningful order; where a tie reaches the top the medal is shared, because nothing separates those rows.
Gauge network
Lakes with a daily level record in New Jersey
Lakes with a linked USGS gauge and a daily water-level record. Readings are daily-batch snapshots, not real-time.
States near New Jersey's heavier not-supporting load
Two EPA ATTAINS peer sets outside New Jersey. The reporting-practice chart above stays on definitive-verdict share; the neighborhoods below emphasize cross-state nearest neighbors when the not-supporting count is in the upper third.
States with a similar reported inventory
Nearest states by lake-type units on the register (611 here).
- South Carolina · 611 units · 0 off
- California · 607 units · 4 off
- Missouri · 623 units · 12 off
- Idaho · 630 units · 19 off
States with a similar not-supporting load
Nearest states by units assessed not supporting a use (583 here). Inventory peers above are omitted.
- New York · 563 not supporting · 20 off
- Florida · 636 not supporting · 53 off
- Wisconsin · 493 not supporting · 90 off
- Massachusetts · 678 not supporting · 95 off
Peers are nearest-neighbor matches on EPA ATTAINS register size and not-supporting counts among states with at least 25 reported units. Impairment peers skip states already listed in the inventory column so the two link sets stay distinct.
Using this state picture
- Comparisons across states hold on shares, not counts: 98.9% of the inventory reported from New Jersey carries a definitive verdict, 4th of 47 comparable states. National rankings
- Fish-consumption verdicts here are assessment decisions. Species-level meal advice comes from the state fish-advisory program. Consumption guide
- Browse every named New Jersey waterbody with a populated record. Browse waterbodies
PlainLakes renders state assessment decisions and federal gauge observations without modification.
Figures on this page are computed from the assessment decisions New Jersey reported to EPA's ATTAINS system and from USGS National Water Information System daily values, no number is typed in by an editor. State counts aggregate every lake-type assessment unit reported by New Jersey, including unnamed units that never receive their own page. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-08-17. Primary sources: EPA ATTAINS and USGS National Water Information System.