Question: where does cape towns water supply come from
[{'answer': 'Steenbras Dam', 'provenance': [{'wikipedia_id': '54197701', 'title': 'Cape Town water crisis', 'start_paragraph_id': 57, 'start_character': 310, 'end_paragraph_id': 57, 'end_character': 323, 'bleu_score': 1.0, 'section': 'Section::::Responses to the water crisis.:Supply augmentation.\n'}]}]