| Nissequogue River | |
| Pushpin Map: | USA New York#USA |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | New York |
| Subdivision Type3: | Region |
| Subdivision Name3: | Suffolk |
| Subdivision Type4: | District |
| Subdivision Name4: | Smithtown |
| Length: | 8.3miles, SN |
| Discharge1 Avg: | 42.2cuft/s |
| Source1: | Caleb Smith Park (at northern end of New Mill Pond) |
| Source1 Coordinates: | 40.8428°N -73.2279°W |
| Source1 Elevation: | 29feet |
| Mouth: | Nissequogue River State Park at Long Island Sound |
| Mouth Coordinates: | 40.9043°N -73.2301°W |
| Mouth Elevation: | 0feet |
The Nissequogue River is an 8.3miles long river flowing from Smithtown, New York into the Long Island Sound. Its average discharge of [1] is the most of any of the freshwater rivers on Long Island. The river, like all other freshwater rivers on the island, is totally derived from groundwater (not from lakes). Its name is derived from one of the Algonquian-speaking Nissequaq tribe in the area.[2]
The river rises south of NY-454 just east of the Hauppauge County Offices and flows into Blydenburgh Park Pond where other tributaries that come from East Hauppauge and Commack meet and are dammed at Blydenburgh Pond. The river continues in a northeasterly direction, picking up additional tributaries from the north in Caleb Smith Park in Smithtown (where special regulation trout fishing is available). It is dammed once more before becoming an estuary at NY-25 where it then flows to Kings Park, New York, entering Long Island Sound at Nissequogue River State Park. Since much of the river is an estuary canoeists travel in both directions based on the tides.
Fish found in the river include Striped Bass, Bluefish, Summer Flounder, Winter Flounder, Porgies, Eels, Brown, Rainbow and Brook Trout, Yellow Perch, Largemouth Bass, Alewives, Herring, Shad, etc.
| Crossings | Carries | Location | Coordinates |
|---|---|---|---|
| Unnamed road bridge | Landing Avenue | ||
| Unnamed road bridge | |||
| Old Main Street Bridge | Pedestrian Bridge | ||
| Unnamed railroad bridge | Long Island Rail Road Port Jefferson Branch Trestle | ||
| Unnamed road bridge | Mill Dam Road (Private) | Blydenberg County Park | |
| Unnamed road bridge | New Mill Road (Long Island Greenbelt Trail) | ||
| Confluence with Northeast Branch at Mill Dam Pond | |||
| Unnamed Road Bridge | Blydenberg County Park Driveway | ||
| Unnamed road bridge | |||
| Unnamed road Bridge | Raoul Wallenberg Drive (County Access Road) | ||
| Crossings | Carries | Location | Coordinates |
|---|---|---|---|
| Unnamed road bridge | Brooksite Drive | Smithtown | |
| Unnamed road bridge | |||
| Unnamed road bridge | |||
| Unnamed road bridge | Terrace Lane | ||
| Unnamed road bridge | Branch Drive | ||
| Unnamed road bridge | |||
| Unnamed road bridge | Bow Drive (Closed to motor vehicles) | ||
| Unnamed road Bridge | |||