In a large pot fitted with a steamer basket, bring water to a boil and add vegetables successively starting with carrots, about 3 minutes, then add broccoli, about 3 more minutes, then zucchini and yellow squash, about 3 to 5 more minutes or until all vegetables are fork tender.
Transfer vegetables to a large mixing bowl and season with garlic powder and salt and pepper and toss with melted butter.
