user: Question: what is the average water sqmi with a population (2010) more than 47 in the brenna Township with Longitude less than -97.171507
Columns: ['Township', 'County', 'Pop. (2010)', 'Land ( sqmi )', 'Water (sqmi)', 'Latitude', 'Longitude', 'GEO ID', 'ANSI code']
Types: ['text', 'text', 'real', 'real', 'real', 'real', 'real', 'real', 'real']
Sample row: ['Baden', 'Ward', 35.0, 34.753, 0.94, 48.588295, 102.048091, 3810104140.0, 1759673.0]
SQL:

assistant: SELECT AVG("Water (sqmi)") FROM "Table" WHERE "Pop. (2010)" > 47.0 AND "Township" = 'brenna' AND "Longitude" < -97.171507;