Heat the olive oil in a large skillet and cook and stir the ground lamb, garlic, and onion powder until the lamb is no longer pink, breaking the meat apart as it cooks. Stir in lemon juice, cinnamon, and oregano; continue to cook, stirring occasionally, until all the liquid in the skillet evaporates and the lamb and garlic are very well browned, about 20 minutes.
Pour in the water and potatoes, bring the mixture to a boil, and reduce heat to medium-low. Simmer until the potatoes are very tender and beginning to break apart, about 20 minutes. Mash potatoes with a spoon against the side of the skillet to help them thicken the sauce. Season to taste with salt and pepper. Simmer until the gravy is thickened and the flavors have blended, about 10 more minutes (1 hour total). Stir occasionally during cooking.
Bring a large pot of lightly salted water to a rolling boil; cook the linguine in the boiling water until cooked through, but still firm to the bite, about 11 minutes. Drain. Transfer the cooked pasta to plates and top with lamb gravy.