BLACK HAWK, La. – The concept of how the Sidney A. Murray Jr. Hydroelectric Station works is simple; its system of controls, complex; and its size, massive.

Water diverted into the channel from the Mississippi River rushes into the plant’s generating units, where it is used to turn turbines to produce electricity. The water then exits into Old River, then into the Atchafalaya River. Hydraulic pumps control water input. The plant handles up to 1.275 million gallons of water a second, the most water of any low-head hydro plant in the world.

&uot;Low-head&uot; means that the plant generates power using a relatively small difference in height between two rivers. On Monday, the difference between the Mississippi and Atchafalaya rivers was 17.4 feet.

The number of turbines that are operating at any one time – the plant has eight turbines in all – depends on the current &uot;head,&uot; or difference in height between the two rivers, and several other factors.

Since the Mississippi River is currently so low, only three of the plant’s turbines are operating. But the plant’s 31 workers are not standing idle. Instead, they are using the time for maintaining equipment and upgrading such things as computer systems.

&uot;It’s good that we have the chance to do that – but we’d rather have higher water,&uot;&160;Ralph Laukhuff Jr., manager of corporate relations and river survey for the Louisiana Hydroelectric Limited Partnership, said during a recent tour of the facility.

In the middle of the plant lies an open floor – the &uot;dance floor,&uot; they call it – where employees take parts for maintenance. On that floor and throughout the plant, the air is noticeably cool because it is dehumidified to protect equipment.

In the plant’s control room, an operator watches a wall full of gauges, digital numbers and lighted buttons, his eyes darting from one control to another.

A buzzing alarm tells him its time to reset one gauge; no sooner has he sat down in his swivel chair than another buzzer goes off.

On another wall to his left is a bright red instrument panel that will tell him where a fire is in the event of a blaze.

&uot;Safety is our first concern,&uot; Laukhuff said.

All the room’s controls are timed, keeping a record of plant activities within a millisecond.

There are two operators at the plant at all times:&160;one to man the control room and another to a close eye on the outside of the plant.

On top of the structure, massive cranes extract debris from the Mississippi River side and place it on the Atchafalaya side – except for appliances and materials that can be recycled, which are temporarily placed on the river banks.

In all, the facility is 456 feet long, longer than one-and-a-half football fields; 123 feet tall or 13 stories, most of which are underwater; and 140 feet wide, wider than a 12-lane freeway.

The structure, made of hollow steel walls filled with concrete, weighs about 25,000 tons. The plant has produced an average of 900 gigawatts per year, although it only produced 800 gigawatts last year, still enough to light a city of 150,000 people for a year.

The hydro plant produces up to 192 megawatts of electricity at one time, but since there is no way to store electric power once it is produced, it is transferred to a nationwide electric &uot;grid.&uot; So that power actually gets to LEPA through the grid.

&uot;The plant,&uot; Laukhuff said, &uot;is something you just have to see for yourself to get a real appreciation of.&uot;