Cyanobacteria advisory (harmful blue-green algae) reported, May 1, 2025

Advisory active · NJDEP Harmful Algal Bloom Program (Division of Water Monitoring, Standards and Pesticide Control)

Source: NJDEP Harmful Algal Bloom Program (Division of Water Monitoring, Standards and Pesticide Control), record f0a44435-33df-4ef4-97f5-ca1a38124c55, updated by the source Apr 22, 2026, 10:13 AM EDT, retrieved 2026-11-02 21:19 UTC · Read the original notice

Current status from this report

This report does not set a map status as of Nov 2, 2026, 4:26 PM EST. Check its dates and the status rules.

A report is not a test of the water. See how we assign statuses.

Read the original notice · Report an error

1. Reported wastewater outlet

Operator named in the record: not named. Outlet: not stated. Location: 41.18368, -74.32557; location source: given in the source record.

Outfall: a pipe or outlet where wastewater enters a water body.

2. Waters named in the notice

The notice names: “Greenwood Lake”. Not linked to a mapped water.

3. Estimated downstream stretch

We estimate routes only on rivers before they become tidal. We do not estimate routes through tidal water or lakes.

Map sources: water outlines and launches from OpenBoatLaunch and OpenStreetMap contributors (Open Database License); wastewater outlets from EPA and state records; downstream estimates by DirtyWaterWatch using U.S. Geological Survey maps and flow data. Base map: OpenFreeMap and OpenMapTiles.

Open on the main map

When it happened and when it was reported

Event and notice times use Eastern Time (EST or EDT). Retrieval times use Coordinated Universal Time (UTC).

Started: May 1, 2025, 9:06 AM EDT
Ended: not reported
Detail provided by the source: Times known to the minute
Reported to the source: not given
Published: not given
Source last updated: Apr 22, 2026, 10:13 AM EDT
Last retrieved by DirtyWaterWatch: 2026-11-02 21:19 UTC

What and how much

Type: Cyanobacteria (harmful blue-green algae) can make water unfit for contact; the issuing authority decides when its advisory ends.
Status in the record: Advisory active
Material: not stated
Volume: volume not reported (not stated whether estimated or measured)
Volume as reported: none

Advice from NJDEP Harmful Algal Bloom Program (Division of Water Monitoring, Standards and Pesticide Control)

“NJDEP HAB alert tier at this site: Advisory.”
NJDEP Harmful Algal Bloom Program (Division of Water Monitoring, Standards and Pesticide Control) · NJDEP HAB Dashboard: the current alert at a site is its latest sample's tier (HAB Watch, Advisory, Warning, Danger); no fixed window

Advice period: This report does not state a period. See the rule DirtyWaterWatch applies and its source.
Basis: NJDEP HAB Dashboard: the current alert at a site is its latest sample's tier (HAB Watch, Advisory, Warning, Danger); no fixed window

Source and versions

Source: Division of Water Monitoring, Standards and Pesticide Control
Source record number: f0a44435-33df-4ef4-97f5-ca1a38124c55
Original notice: Read the original notice
Earlier version: None: this is the first record
Later versions: None

Record details

Record details
Record identifier	nj-hab:f0a44435-33df-4ef4-97f5-ca1a38124c55
Source identifier	nj-hab
Source record number	f0a44435-33df-4ef4-97f5-ca1a38124c55
Earlier version	Not provided
Type	Cyanobacteria advisory (harmful blue-green algae)
Status in the report	Advisory active
Sewer operator identifier	Not provided
Sewer operator	Not provided
Federal wastewater discharge permit (NPDES)	Not provided
Outlet number	Not provided
Outlet name	Not provided
Water named in the report	Greenwood Lake
Linked waters	Not provided
How this report was linked to the water	not linked to a mapped water
Latitude	41.184
Longitude	-74.326
Location source	given in the source record
Location accuracy, in metres	Not provided
Started	May 1, 2025, 9:06 AM EDT (2025-05-01T09:06:00-04:00)
Ended	Not provided
Detail provided by the source	to the minute
Reported to the source	Not provided
Published	Not provided
Source last updated	Apr 22, 2026, 10:13 AM EDT (2026-04-22T10:13:00-04:00)
Last retrieved by DirtyWaterWatch	Nov 2, 2026, 4:19 PM EST (2026-11-02T21:19:42Z)
Material	Not provided
Volume, in gallons	Not provided
Volume as reported	Not provided
How volume was determined	not stated whether estimated or measured
Authority	NJDEP Harmful Algal Bloom Program (Division of Water Monitoring, Standards and Pesticide Control)
Advice	NJDEP HAB alert tier at this site: Advisory.
Advice period, in hours	Not provided
Basis of the advice period	NJDEP HAB Dashboard: the current alert at a site is its latest sample's tier (HAB Watch, Advisory, Warning, Danger); no fixed window
Original notice	https://www.arcgis.com/home/item.html?id=49190166531d4e5a811c9a91e4a41677

Original source data

{
  "waterbody": "Greenwood Lake",
  "site_id": "NJ/NY border",
  "municipality": "Not in NJ",
  "county": "Not in NJ",
  "bathing_beach": "NA",
  "visits": [
    {
      "objectid": 1926,
      "sitevisitdate": "2025-05-01T09:06:00-04:00",
      "siteid": "NJ/NY border",
      "advisorytier": "Advisory",
      "advistorytrigdt": "2025-05-09T12:00:00-04:00",
      "algaeobserved": "No",
      "cellct": 24250,
      "microcystins": 3.29,
      "cylindrospermopsin": 0.48,
      "anatoxin": 0,
      "saxitoxin": 0,
      "predomtaxa": "Aphanizomenon/Cuspidothrix",
      "toxinpresent": null,
      "comments": null,
      "EditDate": "2026-08-27T08:43:51-04:00"
    },
    {
      "objectid": 2184,
      "sitevisitdate": "2025-08-19T11:18:00-04:00",
      "siteid": "NJ/NY Border",
      "advisorytier": "Advisory",
      "advistorytrigdt": "2025-08-22T12:00:00-04:00",
      "algaeobserved": "Yes",
      "cellct": 19750,
      "microcystins": 3.92,
      "cylindrospermopsin": 6.36,
      "anatoxin": 3.46,
      "saxitoxin": 0.03,
      "predomtaxa": "Phormidium",
      "toxinpresent": null,
      "comments": "Not as green as other sites",
      "EditDate": "2026-08-27T08:43:51-04:00"
    },
    {
      "objectid": 2332,
      "sitevisitdate": "2026-04-22T10:13:00-04:00",
      "siteid": "NJ/NY border",
      "advisorytier": "Advisory",
      "advistorytrigdt": "2026-05-07T12:00:00-04:00",
      "algaeobserved": "No",
      "cellct": 22000,
      "microcystins": 2.912,
      "cylindrospermopsin": null,
      "anatoxin": null,
      "saxitoxin": null,
      "predomtaxa": "Planktothrix",
      "toxinpresent": null,
      "comments": null,
      "EditDate": "2026-08-27T08:43:51-04:00"
    }
  ],
  "credit": "NJDEP HAB Dashboard (provided for information purposes only; not monitored 24/7)",
  "current_tier": "Advisory",
  "highest_tier": "Advisory",
  "last_confirmed_basis": "sample time"
}

Staff names, email addresses and phone numbers are removed from source data before it is stored.