Pha loãng và xả nước có thể đạt được chất lượng được cải thiện trong các hồ eutrophic bằng cách giảm nồng độ hạn chế chất dinh dưỡng (pha loãng) và bằng cách tăng tỷ lệ trao đổi nước (xả nước). Cả hai quá trình có thể làm giảm sinh khối tảo sinh vật phù du, bằng cách giảm nồng độ luồng hạn chế chất dinh dưỡng, dẫn đến nồng độ hồ giảm, tối đa nhiên liệu sinh học phụ thuộc. Bằng cách tăng đầu vào nước, tỷ lệ xả nước được tăng lên, do đó làm tăng tỷ lệ. | Dilution and Flushing INTRODUCTION Dilution and flushing can achieve improved quality in eutrophic lakes by reducing the concentration of limiting nutrient dilution and by increasing the water exchange flushing rate. Both processes can reduce the biomass of plankton algae by reducing the inflow concentration of limiting nutrient resulting in a decreased lake concentration on which maximum biomass depends. By increasing the water input the flushing rate is increased which in turn increases the loss rate of plankton algae from the lake. Dilution can be effective even when the increase in flushing rate is insufficient to cause a significant loss of algae. On the other hand flushing rate increase can cause a significant loss without achieving a reduction in the limiting nutrient concentration. Other effects of dilution are also possible such as increased vertical mixing and a decrease in the concentration of algal excretory products which can influence the kinds and abundance of algae Keating 1977 . Dilution is usually feasible only where large quantities of low-nutrient water are available. Treatment effectiveness is greatest when dilution water is low in limiting nutrient concentration relative to that in the lake and its natural inflow. Lake nutrient concentration can be more effectively lowered if dilution water is the dominant inflow. In some instances improvements can be achieved by adding water with moderate to high nutrient content but these results are less certain than with low-nutrient water largely because lowering the lake concentration is more effective at reducing biomass than washout. Dilution and flushing have worked successfully in several lakes. Green Lake in Seattle Washington was improved markedly by adding city water beginning in the 1960s Oglesby 1969 . Moses Lake in eastern Washington has received Columbia River dilution water on a regular basis since 1977 resulting in substantial improvement in lake quality Welch and Patmont 1980 Welch and
