Stormwater runoff, caused by rainwater running off impervious pavement, is a principal cause of urban waterway pollution nationwide.

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Property rights, she says, could not have been the principal cause because England and many other societies had stable and secure property rights for a long time.

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Other supporters of the prime minister are calling for Mr Fini, the principal cause of Mr Berlusconi's weakening grip on office, to resign as speaker of the lower house.

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It is true that industry consolidation has contributed to higher fares in some markets, although the principal cause of higher fares over the last several years has been higher oil prices.

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Even worse, hidden fees and expenses can erode principal and cause investors to lose future purchasing power.

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"The board did the right thing in preserving the principal of having nine at-large seats, " said Common Cause's Simon.

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