( ( Lake Superior ) ( ( ( ( serves ( as ( ( the headwaters ) ( for ( the ( other ( four ( Great Lakes ) ) ) ) ) ) ) ) , ) ( ( ( receiving ( its water ) ) mostly ) ( from ( precipitation ( and ( surface runoff ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Lake) (NNP Superior)) (VP (VBZ serves) (PP (IN as) (NP (NP (DT the) (NNS headwaters)) (PP (IN for) (NP (DT the) (JJ other) (CD four) (JJ Great) (NNS Lakes))))) (, ,) (S (VP (VBG receiving) (NP (PRP$ its) (NN water)) (ADVP (RB mostly)) (PP (IN from) (NP (NN precipitation) (CC and) (NN surface) (NN runoff)))))) (. .)))
Lake Superior serves as the headwaters for the other four Great Lakes, receiving its water mostly from precipitation and surface runoff.
(ROOT (S (NP (NP (NN Precipitation) (CC and) (NN runoff)) (PP (IN in) (NP (DT the) (NN water) (NN cycle)))) (VP (VBP are) (ADVP (RB primarily)) (ADJP (JJ responsible) (PP (IN for) (NP (NP (DT the) (NN creation)) (PP (IN of) (NP (DT a) (NN lake))))))) (. .)))