Int. J. Environ. Res. Public Health 2010, 7 1. Introduction 2438 The deterioration of the water quality of inland water bodies has been a serious ecological and social problem in China, since many lakes (both natural and artificial) and rivers are the main sources of drinking water, as well as water for agricultural use. With the increasing shortage of available water resources, the protection and maintenance of water quality have been a primary objective of watershed or water resources management. Eutrophication is a persistent water quality problem affecting the ecological health of many shallow lakes [1]. Lake eutrophication and aquatic ecological degradation have attracted wide attention over the last decades for their harmful influences on human health [2]. Some algae causing eutrophication can produce toxins such as microcystin, which is recognized as an important cause of liver cancer. Besides the toxins in eutrophicated water being harmful for drinking, they can also be accumulated in the body of aquatic foods, such as fish, shrimp, shellfish and so on. Humans and animals who consume contaminated water and food can become poisoned or even worse, killed. Furthermore, if the drinking water sources such as lakes and reservoirs are eutrophicated, the overgrown algae will affect the working of water treatment plants by blocking filters. To remove the smell and toxins of the water and remediate water eutrophication, large amounts of chemicals are often used, which will degrade the quality of tap water and affect drinking water safety, so monitoring eutrophication is important to human health. Phytoplankton primary production is regard as a reliable and accurate indicator for eutrophication assessment [3]. Numerous researchers, after analyzing the physicochemical and ecological processes of lakes and their effects on phytoplankton [4,5], have found that chlorophyll-a (Chl-a) is a fundamental proxy for phytoplankton abundance, which is widely used in recent research [6]. Chl-a is a green pigment found in plants trapping sunlight for photosynthesis, and its concentration in the aquatic environment is an indicator of phytoplankton abundance, tropic state, and biomass [7]. Chl-a has been long applied as a trophic condition index of water bodies. Steele summarized the use of Chl-a as an indicator of photoautotrophic biomass based on its relationship with primary productivity [8]. Cullen elaborated the application of Chl-a as an index for biomass of primary producers [9]. Chl-a biomass reflects the net result of growth and loss in pelagic waters. Algal biomass, which is closely related with planktonic primary production, is a universally acknowledged indicator of trophic state, because it is the visible manifestation and part of the process of eutrophication [10]. Therefore, as the most serious pollution of lakes in China, phytoplankton blooms (or called algal blooms) can be monitored with the index of Chl-a [11] and it is accepted that Chl-a concentration in a water body is an important index for detecting the degree of pollution in inland water such as lakes, rivers, etc. [12]. Although Chl-a is relatively easily measured in comparison with algal biomass, Chl-a monitoring through in situ sampling is costly and time-consuming. The difficulty in achieving continuous water quality sampling is a tremendous barrier in water quality monitoring and forecasting [13]. With the development of remote sensing, especially hyperspectral scanning technology, remote sensing holds significant potential to enhance regional monitoring and assessment of lake water quality and trophic conditions [14], and by offering a useful and cost-effective approach to evaluate Chl-a, characterized by rapid results, low costs, and convenience for dynamic monitoring, remote sensing has become an important means to estimate Chl-a levels in inland lakes.