Take each spear of asparagus and break it towards the end, wherever it naturally snaps, to remove woody ends. Place asparagus in a microwave-safe glass container with a lid. Pour in water.
Roll lemon on a flat work surface to release the juices; slice in half. Squeeze each half over the asparagus. Sprinkle with pepper and garlic powder.
Cover container and place in the microwave. Cook on high until tender-crisp, 5 to 6 minutes. Drain and let stand for 5 minutes before serving.