. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. 76 CALIFORNIA FISH AND CAME DISCUSSION It has often been observed that newly formed reservoirs begin in an enriched or highly productive state resulting from the decomposition and subsequent nutrient release of recently flooded land {Visser1970, Mitchell 1973). However, this may be offset by increased flushing or shortened retention time. Taylor (1971), in a study of six TVA reservoirs, found reservoirs with a longer retention time te
. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. 76 CALIFORNIA FISH AND CAME DISCUSSION It has often been observed that newly formed reservoirs begin in an enriched or highly productive state resulting from the decomposition and subsequent nutrient release of recently flooded land {Visser1970, Mitchell 1973). However, this may be offset by increased flushing or shortened retention time. Taylor (1971), in a study of six TVA reservoirs, found reservoirs with a longer retention time tended to be more productive, possibly because nutrients were changed to more available forms. Nicola and Borgeson (1970) observed that a high rate of flushing retarded nutrient accumulation. This is particularly critical to produc- tivity in reservoirs with outlet structures that draw water from the hypolimnion, as is the case in Magalia Reservoir. In Paradise and Magalia Reservoirs, the increased flushing during a period of high-rainfall years appears to have reversed any trend toward eutrophication. Rainfall data was collected at Paradise Reservoir by DWR. 1972 and 1976 were relatively dry years (annual total 127 cm) (Figure 6). The increase in the level of trophic state indicators, nutrient concentration and phytoplankton volume observed in 1976 was reversed in 1978. By 1980 the reservoirs were approaching their 1974 trophic condition (total nitrogen < mg/l-N, total phosphorus < mg/l-P, phytoplankton < x lOVVml). Monthly Rainfall (Inches) at Parad i sc Rescrvo:r Annual Totals (Inches) 1972 1974 1976 1978 1980 64 . 57 Jan Feb Mar Apr May FICURE 6. DWR Precipitation Record at Paradise Dam for selected years June. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the o
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