In a large saucepan, bring the water to a boil. Stir in the rice and salt. Reduce heat to low, cover, and simmer 15 – 20 minutes, or until rice is tender and water is absorbed.
While rice is simmering, heat oil in a large skillet over medium heat. Add the spinach. Sauté until spinach is wilted, about 5 minutes.
Add the spinach to the rice when it’s done, along with the scallions, lemon juice, butter, dill, and lemon zest. Finally, stir in the feta cheese. Serve.