Lake Mead is a reservoir in the desert, so the level it is being held at this month decides where the shoreline is and how far down the ramp you back the trailer. Lake Tahoe is the other kind of water entirely, deep and cold, with enough open surface that an afternoon wind has a long fetch to work with before it reaches you. Pyramid Lake has no outlet at all. What a person launching on any of them wants is some idea of what is under the boat before the ramp goes out of sight behind a point.
This pack carries 1,802 charted water bodies. Of those, 731 are named, and 111 of the named lakes measure more than a square kilometer, which ranks 21st among the 48 state packs. The largest it carries is Lake Mead at 546.1 square kilometers, or 134,944 acres, measured off the chart polygon itself rather than quoted from a brochure.
On raw water body count this pack sits 41st of the 48, and on named water it sits 40th. Both of those numbers are a fact about the Great Basin rather than about the chart. Most of this country drains to nowhere in particular, and there are not many farm ponds out in the sage.
The third count is the one worth reading. 111 of the named lakes are larger than a square kilometer, which puts the pack 21st of 48, far ahead of where the raw count lands. The water out here arrives in a small number of very large pieces. Seven of the named lakes the pack carries are over 100 square kilometers, and on water that size the question at the ramp is not which cove to fish. It is whether you want to be four miles out when the wind comes up.
| Lake | Charted surface area |
|---|---|
| Lake Mead | 546 km² (134,944 acres) |
| Lake Tahoe | 495 km² (122,366 acres) |
| Pyramid Lake | 439 km² (108,454 acres) |
| Mono Lake | 182 km² (44,899 acres) |
| Middle Alkali Lake | 149 km² (36,917 acres) |
| Walker Lake | 119 km² (29,504 acres) |
| Lake Mohave | 111 km² (27,429 acres) |
| Upper Lake | 57 km² (14,060 acres) |
| Rye Patch Reservoir | 46 km² (11,416 acres) |
| Lower Lake | 40 km² (10,008 acres) |
| Lahontan Reservoir | 40 km² (9,934 acres) |
| Humboldt Salt Marsh | 40 km² (9,785 acres) |
The twelve largest named lakes the Nevada pack carries, by charted surface area, measured from the chart polygon itself. The pack carries 1,802 charted water bodies in all, 731 of them named, and 111 named lakes larger than one square kilometer.
NOAA charts the coast. There is no NOAA chart for Lake Mead, and there is not one for Rye Patch either. Inland, Helm builds depth from state elevation surveys, and the water bodies themselves come from the National Hydrography Dataset. Those two sources together are the reason a reservoir is charted water in Helm instead of a blue shape with a name printed across it. The outline knows where the water sits, the survey underneath it knows how far down the bottom goes, and a line you draw across a cove comes back with a profile and a shallowest point that your draft can be measured against.
A reservoir also sits at whatever level the people running the dam are holding it at, and on this water that moves through the season. So a contour on a reservoir gets read differently from a sounding on the coast. The ground under the water does not move. The creek channel the valley had before the dam is still the deepest line through it, the benches on either side are still benches, and the level only decides how much of each one is wet on the day you are there.
That is why the contour you learn in spring is still the right map in September on the same reservoir. With your draft on the chart, the thing to watch for is the shoulders going shaded while the old channel stays open, because that shape holds at any level. Only the waterline moved.
Measured from the chart polygon, largest first.
Walker Lake at 119.4 square kilometers and Lake Mohave at 111.0 sit next to each other on that list and have almost nothing else in common. Mohave is river water held between two dams on the Colorado, long and narrow, and the upper end of it still reads like river. Walker is a terminal lake with nothing flowing out of it. Same acreage on paper, two completely different days on the water.
Mono Lake at 181.7 square kilometers (44,899 acres) is fourth on the list, and Middle Alkali Lake at 149.4 (36,917 acres) is fifth, which surprises people who assume the big water is all in the south.
Rye Patch Reservoir measures 46.2 square kilometers (11,416 acres) in the pack and Lahontan Reservoir 40.2 (9,934 acres). Both are storage, so those acreages describe one state of a lake whose edge moves with the water year. The figure is still worth having. It tells you the scale of what you are launching onto, and the contours beneath it are the part that stays where it is.
Washoe Lake at 22.4 square kilometers (5,535 acres) and Humboldt Lake at 36.0 (8,896 acres) are smaller water again, shallow enough that a boat with any draft on it wants the shading on before it goes wandering off the launch.
Up in the high basins the names do most of the explaining. Upper Lake at 56.9 square kilometers and Lower Lake at 40.5 are the big ones, with Alkali Lake at 15.2, Massacre Lake at 14.9, Goshute Lake at 17.0 and the Humboldt Salt Marsh at 39.6 around them. This is seasonal country. The pack carries the surveyed shape of each basin, which is exactly what you want when you are working out where the edge of the water is somewhere with no road signs and no bars on the phone. The pack also carries something called Y Pond at 6,425 acres, and something called Big Water at 5,980, so the naming out there is its own reward.
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.
Yes. Inland depth in Helm comes from state elevation surveys rather than from NOAA charts, so the water itself carries contours and a depth number read against your draft. A reservoir sits at whatever level it is being held at, and the ground under it is the part that stays put, so the benches either side of the old creek channel shade while the channel stays open. That is the same line in June that it is in September. Lake Mead is the largest water body this pack carries, at 546.1 square kilometers, or 134,944 acres.
Yes. The packs are cut to a box rather than to a state line, so water on a border can sit in two packs at once. Tahoe is carried here at 495.2 square kilometers (122,366 acres), second in size only to Lake Mead among the lakes in this pack, and Mono Lake at 181.7 square kilometers (44,899 acres) falls inside the same box. Oregon, Idaho, Utah and Arizona each have a pack of their own if your water runs over one of those lines.
Pyramid Lake at 438.9 square kilometers (108,454 acres), Walker Lake at 119.4 (29,504 acres), Lake Mohave at 111.0 (27,429 acres), Rye Patch Reservoir at 46.2 (11,416 acres) and Lahontan Reservoir at 40.2 (9,934 acres) are among the larger ones. The pack holds 731 named water bodies out of 1,802 charted in total. It downloads once at home and works at a ramp with no signal.
Helm Boating