Most of the water in this pack is small. The pack carries 1,943 charted water bodies and 53 named lakes larger than a square kilometer, so a normal Saturday starts on something you can see across from the ramp. The bigger ones are worth knowing by size. Lake Hopatcong is the largest lake the pack carries, at 10.0 square kilometers, 2,471 acres. Round Valley Reservoir is 9.1 square kilometers, 2,249 acres, close enough to Hopatcong that the two are the same class of water, and Greenwood Lake runs 7.4 square kilometers, 1,829 acres, which is enough fetch for the wind to put up a chop by mid afternoon.
The water bodies themselves come from the National Hydrography Dataset, and the depth on them is built from state elevation surveys. Of the 1,943 water bodies in the pack, 1,058 carry a name. That sourcing is the reason a reservoir here shows up as charted water with contours and a depth reading on it, and it is what lets you plan a line across a lake against the draft of your own boat before you tow anywhere.
Three figures describe this pack: 1,943 charted water bodies, 1,058 of them named, and 53 named lakes over a square kilometer. Put them next to each other and you get the shape of the boating. About one named lake in twenty is bigger than a square kilometer, so the water that gets run here is mostly modest, and the handful of large basins are the ones people drive to.
The other 885 water bodies carry no name in the hydrography data and are charted all the same, with their shoreline drawn. That matters at the small end of the state, where a two hundred acre impoundment with a gravel ramp is a normal place to spend a morning and is not going to appear on any nautical chart.
| Lake | Charted surface area |
|---|---|
| Lake Hopatcong | 10 km² (2,471 acres) |
| Round Valley Reservoir | 9 km² (2,249 acres) |
| New Croton Reservoir | 9 km² (2,150 acres) |
| Wanaque Reservoir | 8 km² (1,952 acres) |
| Greenwood Lake | 7 km² (1,829 acres) |
| Lake Nockamixon | 6 km² (1,408 acres) |
| Van Sciver Lake | 6 km² (1,384 acres) |
| Spruce Run Reservoir | 6 km² (1,359 acres) |
| Lake Tappan | 4 km² (914 acres) |
| Union Lake | 4 km² (865 acres) |
| Boonton Reservoir | 3 km² (791 acres) |
| West Branch Reservoir | 3 km² (766 acres) |
The twelve largest named lakes the New Jersey pack carries, by charted surface area, measured from the chart polygon itself. The pack carries 1,943 charted water bodies in all, 1,058 of them named, and 53 named lakes larger than one square kilometer.
There is no NOAA chart for a reservoir. NOAA charts the coast, the intracoastal and navigable rivers, and a basin holding back a creek behind an earth dam is none of those. Inland depth in Helm is built from state elevation surveys instead, and the outline of the water comes from the National Hydrography Dataset.
That is the difference between a lake being a blue shape and being water you can plan across. With a surveyed bottom under the outline, a line drawn from the ramp to the far bank has a depth profile along it, and your draft has something to be measured against. The shading and the router behave the same way on Round Valley Reservoir as they do offshore, which is covered on the depth and routes pages rather than here.
Round Valley Reservoir, Wanaque Reservoir, Spruce Run Reservoir, Boonton Reservoir and Oradell Reservoir are all held at a level somebody decides, and that level is not the same in April as it is in late summer. The bottom does not move. What moves is where the surface sits on it, so a foot off the top takes a foot off every reading in the basin at once.
The useful habit on a drawdown is to read the contour as the shape of the basin and the level as an offset on top of it. The old creek channel through a reservoir stays the creek channel all year. The shoulders on either side of it are the part that comes up, which is why the thing that goes first in a dry August is the shortcut across the flat at the mouth of a cove, while the run down the middle is still there. Check what the pool is being held at, then read the number near your draft with that in mind.
Five lakes in the pack are over 7 square kilometers and they sit close together in size. Lake Hopatcong leads at 10.0, Round Valley Reservoir is 9.1, New Croton Reservoir 8.7, Wanaque Reservoir 7.9 and Greenwood Lake 7.4. Below them the sizes step down hard. Lake Nockamixon is 5.7 square kilometers, Van Sciver Lake 5.6 and Spruce Run Reservoir 5.5, so Spruce Run is a little over half the size of Hopatcong. Lake Mohawk, at 3.1 square kilometers, is under a third of it.
The largest named lakes the pack carries, measured from the chart polygon itself:
The pack is cut to a box rather than to the state line, so a lake sitting near an edge comes in whole. New Croton Reservoir is in this pack at its full 8.7 square kilometers and Van Sciver Lake at its full 5.6, and border water like that can turn up in a neighboring pack too. Download whichever pack covers the water you actually launch on.
Inland lake depth comes from state elevation surveys rather than from nautical charts, and a reservoir sits at whatever level it is being held at that week. Treat the shape and the depth as a guide, keep a lookout, and verify locally.
Depth. Hopatcong is the largest lake the pack carries, 10.0 square kilometers and 2,471 acres, and the depth on it is built from state elevation surveys rather than from a nautical chart. The shoreline itself comes from the National Hydrography Dataset. Enter your draft and the water your boat cannot cross is shaded, so the coves read differently from the open middle before you get there.
The contours describe the shape of the basin, and that shape does not change when the pool drops. What changes is where the surface sits on it, and the drop comes off every reading at once. Read the chart for the shape and the current pool level for the offset. On a drawdown the shoulders beside the old channel are what come up, and the channel through the middle of the basin stays where it was.
Yes. The packs are cut to a box rather than to the state line, so Greenwood Lake comes in this pack at its full 7.4 square kilometers, 1,829 acres, north end included. The same is true of New Croton Reservoir at 8.7 square kilometers and Lake Nockamixon at 5.7. Water near an edge of the box can also appear in a neighboring pack, so download the one that covers the ramps you use.
Helm Boating