How cold is Big Bear Lake right now?

Reading the current lake report from the water district…

Source: Big Bear Municipal Water District.

This is one surface reading for a lake seven miles long. The shallow east end warms first and cools first, the water near the dam is the deepest and the slowest to change, and a few feet down it is colder than the number above everywhere on the lake.

The water district reports the level as feet below full pool rather than as a raw elevation. Full pool is 6,743.2 feet above sea level at the dam, so the surface elevation shown above is that figure minus the feet-below-full reading — arithmetic on the district's own numbers, not a separate measurement.

Big Bear Lake is a reservoir fed almost entirely by snow and runoff from its own small watershed. It fills in big snow years and draws down through dry ones, so sitting several feet under full is the ordinary state of things rather than a headline. What the level actually changes for most people is shoreline. A low lake means wider beaches, a longer walk from the parking area to the water, rocks and stumps exposed that are usually submerged, and launch ramps that can close when the water pulls back past the end of the concrete.

Deliberately no "percent full" figure here. Feet of depth and acre-feet of water are not proportional in a basin this shape, and converting between them without the district's own storage curve would produce a confident-looking number that is wrong.

Temperature is the single most useful number on this page for an angler, because it decides where in the water column the fish are. Cold water in the 40s and low 50s holds trout near the surface and close to shore. As the surface climbs past the mid-60s in summer they drop to find cooler water, and the shallows that fished well in April stop producing. Autumn cooling brings them back up again.

Stocking windows come from the California Department of Fish and Wildlife's provisional planting schedule for Big Bear Lake. A window is an intention, not a delivery receipt — the truck can be early, late or diverted.

Parts of it do. In a cold winter the shallow east end and the sheltered coves skin over while the deeper water near the dam stays open, and the ice forms and breaks up again with every warm spell. From the shore it can look like one solid sheet when it is nothing of the kind.

Treat all ice on Big Bear Lake as unsafe. No agency measures or certifies ice thickness here, and nobody publishes a safe-to-walk-on figure — so there is no reading this page could show you that would make it safe. Ice fishing and skating happen on purpose-managed water elsewhere, not on a reservoir with moving water under it.

Clarity swings with the season rather than by the day. Spring runoff carries silt in and the water turns off-colour for a few weeks. Wind stirs the shallow east end far more than the deep water by the dam, so the same afternoon can look murky at one end of the lake and clear at the other. Late summer warmth is when algae is most likely, and a bloom can tint the water green and leave scum along the downwind shore.

No live clarity or algae reading is published for this lake, so this page does not show one. Any health advisory about the water — an algae warning, a swim advisory — comes from the water district and San Bernardino County, and it overrides anything here.

Temperature, level and stocking above are read automatically from the water district and the state wildlife department, and refresh on their own while this page is open. If a source cannot be reached, this page says so rather than showing yesterday's reading as if it were current.