Just as recent storms revealed weaknesses in Northern California’s dams and levees, they also exposed problems with Sacramento-area wastewater systems that failed to contain sewage. Record precipitation in the last two months created more pressure than some sewer lines and plants could handle. From Jan. 1 to March 2, more than 1 million gallons of wastewater spilled in the capital region, most into waterways, according to reports made by sewage districts to the State Water Resources Control Board. While spills occurred in several communities, most were in areas served by the Sacramento Area Sewer District and the city of Placerville.