Up in the hills the Corps put dams across the Yazoo headwaters, and Sardis, Grenada, Arkabutla and Enid all run differently depending on where the pool is being held that month. Out in the Delta the lakes are old bends of the river, Eagle Lake, Lake Washington, Lake Whittington, Tunica Lake, narrow and curved with the deep water still on the outside of the turn. East of there the Tennessee Tombigbee pools run one into the next behind their locks, which is river water wearing a lake name. At the bottom of the map it goes brackish and opens into Pontchartrain, big enough that a north wind has room to build a chop across the whole of it.
The pack for this state carries 9,223 charted water bodies, the eighth largest count of the 48 state lake packs. Of those, 1,182 carry a name, and 90 of the named ones clear a square kilometer, which is about 247 acres. The outlines come from the National Hydrography Dataset and the depth under them is built from state elevation surveys, so the water on the screen has contours and a reading on it rather than a flat blue fill.
A count of 9,223 is high for a state pack. Only seven of the 48 carry more. The reason is the ground itself, which is flat, floods, and holds what it takes: brakes behind the levee, borrow pits alongside the highway embankments, sloughs down in the bottoms, ponds cut for catfish. Water accumulates here in a way it does not in a state made of hills.
Names are the scarcer thing. With 1,182 named out of 9,223, there are 8,041 pieces of charted water that a local describes rather than calls by a label, and they are on the chart all the same. Of the named ones, 90 are larger than a square kilometer. That second figure is usually the one worth checking. It is the count of water big enough that you plan a run on it instead of looking across it from the bank.
| Lake | Charted surface area |
|---|---|
| Lake Pontchartrain | 1,645 km² (406,389 acres) |
| Lake Maurepas | 235 km² (58,119 acres) |
| Sardis Lake | 134 km² (33,087 acres) |
| Grenada Lake | 68 km² (16,927 acres) |
| Arkabutla Lake | 46 km² (11,342 acres) |
| Lake Saint Catherine | 27 km² (6,672 acres) |
| Coffeeville Lake | 26 km² (6,425 acres) |
| Enid Lake | 25 km² (6,252 acres) |
| Bay Springs Lake | 24 km² (6,054 acres) |
| Aliceville Lake | 20 km² (4,868 acres) |
| Eagle Lake | 20 km² (4,819 acres) |
| Lake Eugenie | 18 km² (4,473 acres) |
The twelve largest named lakes the Mississippi pack carries, by charted surface area, measured from the chart polygon itself. The pack carries 9,223 charted water bodies in all, 1,182 of them named, and 90 named lakes larger than one square kilometer.
There is no NOAA chart for a reservoir. NOAA charts the coast and the navigable rivers, and a lake sitting behind an earthen dam was never survey work for a hydrographic office. So inland depth in Helm is built from state elevation surveys instead, and the water bodies themselves come from the National Hydrography Dataset. That is the whole difference between a blue shape with a name on it and water you can lay a route across against your own draft.
The other half of reading a lake is that a reservoir sits at whatever level it is being held at. On these flood control lakes that means a summer pool and a lower winter pool, changed on purpose, with a gauge at the dam that says where it is right now. Read the contour as the shape of the basin, because that part does not move. What moves is the water on top of it. Put the day's pool reading against the contour and you have the number under your hull. The cove that carries you in July is the same cove in January with the flats out of the water and the old creek channel doing all of the work.
Sardis Lake is the largest reservoir the pack carries, 133.9 square kilometers and 33,087 acres. Grenada Lake is almost exactly half of that at 68.5 square kilometers and 16,927 acres, though anyone who has seen Grenada holding flood water will read that figure twice. The acreage is measured from the chart polygon, which is the lake as the outline has it, not the most water the basin has ever held. Arkabutla Lake comes to about a third of Sardis, 45.9 square kilometers and 11,342 acres. Enid Lake is the smallest of the four at 25.3 square kilometers and 6,252 acres. Okatibbee Lake, further south, is 15.2 square kilometers and 3,756 acres.
Then there are the navigation pools, which are a different animal on the same list:
Those are pools behind locks, long and mostly river, so the acreage tells you less than it does on a basin lake. A figure of 6,054 acres on Bay Springs covers water that runs a long way from one end to the other, and almost none of it is wide.
Several of the bigger named lakes on the list are cutoff bends of the river. Eagle Lake is 19.5 square kilometers and 4,819 acres, Tunica Lake 14.8 and 3,657, Lake Mary 13.6 and 3,361, Lake Whittington 13.4 and 3,311, Lake Washington 12.3 and 3,039. Acreage is a poor guide on a horseshoe. The water is narrow and it bends, so the run from one tip to the other is much longer than the figure suggests, and the deep side is still the outside of the old bend, the way the river left it. The ones that keep a connection also come up and go down with river stage, so the gauge is worth a look before you hitch up the trailer.
The packs are cut to a box rather than to a state line, so the southern end of this one reaches the coastal lakes. Lake Pontchartrain is the largest water body the pack carries, 1,644.6 square kilometers and 406,389 acres, seven times the size of Lake Maurepas beside it at 235.2 square kilometers and 58,119 acres. Lake Saint Catherine, 27.0 square kilometers and 6,672 acres, sits in the same corner. Water near a border lands in more than one pack, so all three come down with the Louisiana pack as well, and it makes no difference which one you have.
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. Both are in the Mississippi lake pack with contours and a depth reading on the water itself, Sardis at 133.9 square kilometers (33,087 acres) and Grenada at 68.5 square kilometers (16,927 acres). Inland depth is built from state elevation surveys, since a reservoir is not NOAA chart water. Arkabutla at 11,342 acres and Enid at 6,252 acres come down in the same pack.
Yes, and this is how to use them. A contour describes the shape of the basin, and the basin does not change when the pool does. Take the day's level from the gauge at the dam and read it against the contour to get what is under you. On the Yazoo reservoirs the drop from summer pool to winter pool is exactly what puts the flats dry and leaves the old creek channel as the way through, and that channel is the shape the contours are showing you.
Because the packs are cut to a box rather than to a state line, so water near a border sits in more than one of them. Pontchartrain is the largest water body this pack carries, 1,644.6 square kilometers and 406,389 acres, with Lake Maurepas at 58,119 acres and Lake Saint Catherine at 6,672 acres in the same corner. The same water is in the Louisiana pack.
Helm Boating