For reasons unknown to me at the moment, the USBR is letting water flow over the top of Grand Coulee Dam right now. This is a fairly unusual event. That’s not just water, it’s money running over the top, in the form of revenue foregone by the BPA, which can’t sell electricity the dam doesn’t produce with that water power.
If you have a chance, pop down and see it.
The dam is almost a mile across, and the spill is about 300 feet.

Update
Seems that Lake Roosevelt has to drop right now to meet flood control goals. We wouldn’t want Portland to flood, after all. Here is info about current lake operations the USBR published yesterday:

The elevation of Lake Roosevelt was 1280.4 at 10 a.m. on April 9.

It is antipated the elevation will remain around elevation 1280.0 in order to reach the Biological Opinion operating objective of 1279.9 by April 10. Currently, Grand Coulee Dam is being operated to meet flood control elevations.

The flood control levels are the maximum elevation for Lake Roosevelt. Other factors such as power demand or supplying water downstream for fish can result in elevations under the flood control elevations.

The current flood control elevation is as follows:

April 30 – 1258.5 feet
This is only a prediction and can change due to weather events, power demand or other unforeseen power emergencies.
Lake level forecasts are updated by 3 p.m. each day. Please call 1-800-824-4916 for the updated forecast.