Friday, August 30, 2013

Section 316(b) of The Clean Water Act

The EPA is moving forward on several new rules that would impose strict standards on water management at U.S. power plants. The agency's new rule governing water intake structures at existing power plants is a perfect example.

A juvenile striped bass impinging on water screen

Section 316(b) of the Clean Water Act would affect roughly 670 power plants in the U.S. It would require plants that draw more than 2 million gallons a day and use 25 percent of that water for cooling to install the best technology available (BTA) to minimize the mortality of aquatic life. Losses occur when fish and other organisms become trapped (impinged) against water intake structures or sucked (entrained) into the cooling system and exposed to heat, pressure and machinery. The rule requires the best technology to mitigate what it describes as "adverse environmental impact" resulting from entrainment and impingement.

However, we still don't know what constitutes an "adverse environmental impact" because the rule, which was first introduced in 1972, does not provide a definition. The term has long been understood by the scientific community to refer to adverse changes in the abundance and productivity of fish and other aquatic life.  The problem is this: There is no scientific evidence that shows a reduction in entrainment and impingement would lead to measurable improvements in fish populations.

We recommend Wedgewire Screens as BTA

The 316(b) rule was first enacted in 1972 when Congress passed the Federal Water Pollution Control Act Amendments (Clean Water Act). Since then, the rule has been suspended and rewritten several times in a long and drawn out legal battle between utilities and environmental groups. After 40 years, the EPA is expected to release the final rule in November.

Adverse impacts have been implicitly or explicitly defined as entrainment and impingement per se, irrespective of whether any adverse changes in populations can be demonstrated or predicted. The rarity of documentation of such impacts, after 40 years of operation of large power plants, some of which have been conducting extensive monitoring programs for several decades, provides substantial evidence that impacts related to entrainment and impingement are generally small. (Power Engineering, August 2013)

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