We evaluated the suitability of N,N-dimethylformamide (DMF) for extraction and measurement of chlorophyll in phytoplankton and compared the extraction efficiencies of DMF, dimethyl sulfoxide (DMSO)–acetone, and 90% acetone. Absorbance spectra and specific absorption coefficients of chlorophylls a, b, and c in DMF and 90% acetone are similar. Acidification of 100% DMF extracts of pure chlorophyll a and healthy algal cultures produced acid ratios approximating 1.7. Thus, equations derived from the extinction coefficients of chlorophylls in 90% acetone can be applied to DMF extracts. DMF and DMSO–acetone each extract chlorophyll from green and blue-green algae more effectively than does 90% acetone. DMF is a better extractant than is DMSO–acetone for chlorococcalean species, especially when pigment concentrations are high, but the difference, although significant, is slight. The three solvents are equally efficient in extracting chlorophyll from samples composed of chrysophytes and flagellated chlorophytes. The lack of grinding when using either DMF or DMSO–acetone is a considerable convenience. The potential for destabilized spectrophotometer readings and contamination of the investigator due to the incomplete mixing of DMSO and acetone is eliminated when pure DMF is used.

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Maryland’s cooling-water intake and discharge regulations, the Code of Maryland Regulations (COMAR) 26.08.03, stem from Sections 316(a) and (b) of the Clean Water Act (CWA). COMAR 26.08.03.05 and litigative and administrative rulings stipulate that the location, design, construction, and capability of cooling-water intake structures must reflect the best technology available (BTA) for minimizing adverse environmental impacts (AEIs), providing that the costs of implementing the BTA are not wholly disproportionate to the expected environmental benefits. Maryland law exempts facilities that withdraw less than 10 million gallons/day (MGD) and less than 20% of stream or net flow by the intake. If not exempt, BTA must be installed if the cost of doing so is less than five times the value of fish impinged annually. Through site-specific studies and the use of a Spawning and Nursery Area of Consequence (SNAC) model applied to Representative Important Species, several power plants were evaluated to determine if they have had an adverse effect on spawning and nursery areas of consequence. Examples of application of the Maryland law to a number of power plants in the state are presented, together with the outcome of their evaluation.