Boating this water is not one kind of boating. Lake Tahoe is 495.2 square kilometers of open water, and a crossing there is a piece of planning you do the night before. Don Pedro Reservoir is 44.2 square kilometers of flooded river arms, where most of the day is spent following the old channel up an arm and reading the shoulders on either side of it. Clear Lake, at 159.7 square kilometers, takes wind across the whole of it by afternoon. Shasta Lake and Trinity Lake are within a square and a half of each other in surface area, 64.1 and 62.7, and both of them look like a different lake in October than they did in May. The Salton Sea is the largest single piece of water the pack carries, at 939.1 square kilometers.
The pack carries 6,791 charted water bodies. Of those, 2,073 carry a name, and 282 of the named ones are larger than a square kilometer. The water bodies themselves come from the National Hydrography Dataset and the depth under them is built from state elevation surveys, which is the reason a reservoir arrives on the chart as water with contours and a number on it instead of a blue shape with a name floating over the middle.
Three numbers describe this pack, and they rank differently. The 6,791 charted water bodies put it twelfth among the 48 state lake packs. The 2,073 named ones rank eleventh. The figure that matters most if you tow a boat is the third one: 282 named lakes larger than a square kilometer, which is ninth of the 48, near the top of the set.
A square kilometer is about 247 acres, so that third count is roughly the water big enough that you would bother drawing a route on it rather than eyeballing the far bank. Two hundred and eighty two of those in one pack is a lot of weekends.
Take the named count off the total and 4,718 water bodies here carry no name at all. Farm ponds, settling basins, sag ponds, high country tarns above the tree line. Very few of them are places anyone launches. They are charted as water regardless, which is what you want when you are working out whether the blue off to the left of the arm you are running is part of the same lake.
| Lake | Charted surface area |
|---|---|
| Salton Sea | 939 km² (232,056 acres) |
| Lake Tahoe | 495 km² (122,366 acres) |
| Goose Lake | 385 km² (95,210 acres) |
| Honey Lake | 241 km² (59,626 acres) |
| Mono Lake | 182 km² (44,899 acres) |
| Clear Lake | 160 km² (39,463 acres) |
| Middle Alkali Lake | 149 km² (36,917 acres) |
| Lake Mohave | 111 km² (27,429 acres) |
| Lake Almanor | 101 km² (25,056 acres) |
| Owens Lake | 79 km² (19,472 acres) |
| Lake Havasu | 75 km² (18,483 acres) |
| Eagle Lake | 73 km² (18,063 acres) |
The twelve largest named lakes the California pack carries, by charted surface area, measured from the chart polygon itself. The pack carries 6,791 charted water bodies in all, 2,073 of them named, and 282 named lakes larger than one square kilometer.
There is no NOAA chart for a reservoir. NOAA charts the coast, the intracoastal and the navigable rivers, and a lake sitting behind a dam falls outside all of that. Inland depth in Helm comes from state elevation surveys of the lake bed instead, laid under water bodies taken from the National Hydrography Dataset. That is the step that turns a reservoir from an outline into water you can plan a route across against your own draft.
A surveyed bed elevation does not move. The water standing on top of it does. A reservoir is held at whatever level the operator is holding it at that month, and on a working reservoir in a dry September that can be well below where the ramp was in June. So the contour on the screen describes the shape of the bottom, and the question you answer at the ramp is how much water is over it today. Anyone who runs Shasta Lake or San Luis Reservoir across a full season already reads a lake this way.
With your draft entered, the flats on either side of a submerged creek channel shade while the channel itself stays open, which is the part you use going up an arm you have not run since spring. The depth sources and how the router treats water your boat cannot cross are covered on the depth and routes pages.
The Salton Sea comes in at 939.1 square kilometers, 232,056 acres, close to twice the surface area of Lake Tahoe. After those two the sizes drop away quickly. Goose Lake is 385.3 square kilometers (95,210 acres), Honey Lake 241.3 (59,626), Mono Lake 181.7 (44,899).
Among the reservoirs people hitch a trailer for, Lake Almanor is the big one at 101.4 square kilometers (25,056 acres). Lake Berryessa is 72.8 (17,989), Shasta Lake 64.1 (15,839), Trinity Lake 62.7 (15,493), San Luis Reservoir 51.7 (12,775), Don Pedro Reservoir 44.2 (10,922). Almanor is larger than all five of those. Lake Mohave at 111.0 (27,429) and Lake Havasu at 74.8 (18,483) are the two pieces of river water in the top dozen, and Mohave is half again the size of Havasu.
Two entries carry almost the same name and are not the same water. Clear Lake is 159.7 square kilometers (39,463 acres). Clear Lake Reservoir is 65.1 (16,087). The pack holds both, under their own names, so it is worth a glance at the label before you plan a day against the wrong one. Every acreage above is measured off the chart polygon itself.
The packs are cut to a box rather than to a state line. Water sitting out near the edge of that box is therefore carried by the neighboring pack as well, so a lake toward Oregon, Nevada or Arizona shows up in two of them. If the water you run is out toward a corner, take both packs and stop thinking about it. The Oregon, Nevada and Arizona lake pages cover what those neighbors hold.
One download covers the whole box, not one lake, which is the useful part of a weekend that starts on one reservoir and ends on another two hours up the road. Do it at home on wifi. Ramps on this water sit a long way down a dirt road more often than not, and the chart, the depth shading, the measure tool and the routing all keep working once the pack is on the device.
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. The California lake pack carries Lake Tahoe at 495.2 square kilometers, 122,366 acres measured from the chart polygon, which makes it the second largest water body in the pack behind the Salton Sea. The depth under it comes from state elevation surveys rather than from a NOAA chart, and it is shaded against the draft you enter for your own boat.
Both are carried, as separate water bodies with their own names out of the National Hydrography Dataset. Clear Lake is 159.7 square kilometers, 39,463 acres. Clear Lake Reservoir is 65.1 square kilometers, 16,087 acres, so it is a little over a third the size. Check the label on the water before you plan a run against it.
The contours come from a survey of the lake bed, so they stay where they are while the surface level moves up and down with the water year. Shasta Lake is carried at 64.1 square kilometers, 15,839 acres at full polygon. Read the contour against the level being held that week, and with your draft on the chart the flats on either side of the old river channel shade while the channel stays open ahead of you.
Helm Boating