## 1 Introduction  
Inland water bodies are valuable resources that provide multiple economic, social, and ecological services for domestic, industrial, and agricultural uses. However, agricultural inputs (pesticides, herbicides, and fertilizers), domestic wastewater (organic matter, nutrients, personal care, and pharmaceutical pollutants), and industrial effluents from the freshwater body's catchment area [1, 2, 3], in addition to surface water overutilization for irrigation and industry, decrease both the quantity and quality of inland waters [4]. Good water quality is crucial for long-term aquatic ecosystem health and functioning [5]. Its deterioration can lead to the disturbance of the ecological balance, the loss of biodiversity, and a significant negative impact on the abundance and distribution of native species in the system [6; 7]. In this way, the introduction and proliferation of aquatic invasive alien species are facilitated [8], which can further modify the structure and functions of these aquatic ecosystems. The water hyacinth _Pontederia crassipes_ Mart. (formerly _Eichlornia crassipes_ (Mart.) [PERSON]) is a free-floating and fast-growing perennial aquatic species, and one of the invasive species provoking most concern to freshwater ecosystem managers [9; 10]. It is a native species of South America (Brazil), which has, however, dispersed rapidly throughout the world during the last century [11; 12]. The water hyacinth shows its fastest growth and expansion in warm climate lakes that receive large amounts of nutrients (europhic). Thus, the water hyacinth has expanded in the majority of tropical freshwater bodies all over the world. It can form dense floating mats on the water surface, increasing water loss due to higher evapotranspiration and decreasing water clarity and light penetration depth, oxygenation levels, phytoplankton growth, and biodiversity [10; 12; 13]. Lake Tana is the largest freshwater lake in Ethiopia and provides multiple ecosystem services for the local, regional, and global community, having been declared a world heritage site (Biosphere Reserve, UNESCO) [14] due to its high biodiversity [15; 16]. The Ethiopian government has also identified it as one of the growth corridors for economic development [17]. However, several recent studies have indicated that Lake Tana is one of the most affected basins in Ethiopia due to human activities [18; 19; 20]. Water diversion from the lake, as well as its tributaries, for irrigation and hydropower generation purposes is responsible for water quantity reduction and increased nutrient concentration [21; 22]. Nutrient inputs from agricultural activities and urban areas and sediment load from the catchment area also contribute to increased nutrient concentrations and turbidity, leading to further water quality deterioration [23; 24]. These conditions favored the expansion of the water hyacinth in Lake Tana, which was first observed in the lake in 2011 [13]. Between 2013 and 2017, water hyacinth showed a 66% increase per year, essentially in the northeastern part of the lake [25; 26; 27]. Overall, water bodies infested by water hyacinth are characterized by lower water quality than noninfested areas including higher turbidity, chlorophyll-a (Chl-a), total suspended matter (TSM), and chemical oxygen demand, and lower pH, dissolved oxygen, and nitrate concentrations [11; 13]. Frequent monitoring and assessment of water quality, e.g., Chl-a and TSM, and water hyacinth expansion in Lake Tana are essential for designing both short- and long-term management plans to sustain its resources and ecosystems. Collection of in situ data is extremely labor-intensive and time-consuming and tends to be limited in time and space. Satellite remote sensing plays a significant role in overcoming such bottlenecks for researchers working in dynamic and complex water bodies [28; 29], to capture the spatial and temporal heterogeneities, particularly in freshwater bodies where historical data are highly scarce, such as Lake Tana.