On the Water
The lake, right now
Surface elevation in feet above the 1929 datum, water temperature, and wind where the gauge reports it. Readings are nominally every fifteen minutes; the age of each is on the card, and a card that has not been updated in three hours states as much rather than showing a stale number as though it were current.
Which way it is leaning
The four gauges run a hundred and twenty miles (190 km) from Whitehall to Rouses Point, and they almost never read the same. The difference between the ends is the lake tilted in its basin — wind pushing water downwind, and the whole body then sloshing back. The seiche page is about that motion; this is its current value.
Where it is going
Wind pushes the lake downhill and the lake takes most of a day to answer, which is what makes the tilt predictable at all from a wind forecast. This is the wind-driven part on its own — the slower movement, which is runoff rather than weather, is not forecast here.
How cold it is, and how far down
The Valcour buoy reports a temperature every meter or two, from the surface to the bottom of its string. In summer the top few meters are a different lake from the water below the thermocline, which matters if you intend to be in it.
Where the boundary is going
The thermocline is not a fixed shelf. Wind leaning along the lake tips the whole warm layer, and at this end of it the boundary can move several meters in a day — which is the difference between a comfortable swim and a cold one at the same depth.
What the weather is doing
The National Weather Service issues a recreational forecast for this lake three times a day, in three sections that run its length, with winds in knots and wave heights.
Blooms reported now
Vermont's tracker is a network of people looking at the water and filing what they saw, at one spot, on one day. A report of Generally Safe means somebody looked at that shoreline on that date and saw no bloom. It is not an inspection, not a clearance, and not a statement about tomorrow, or about the next bay along.
Cyanobacteria move with the wind and can build within hours. The absence of a report near you means nobody has filed one — which is the commonest case on this lake, and is not the same as good news. Look at the water yourself before you get into it.
Where to get on the water
Access points from the Lake Champlain Basin Program's layers.