The aimof the paper is to assess the thermal impact of a French pond of 2.2 ha with a weir on a stream of order 1, and to compare this result, on the one hand with the influence of the same body of water made dry, on the other hand with a second pond remaining full. The study is based on 8 years of hourly water temperature measurements. It is context-related in an epistemological consideration leading to a new typology of existing empirical approaches (deletion, restoration, transfer, reconstruction, air-water equilibrium and gradient-reconstitution temperatures) and questioning the assimilation between the inlet and outlet temperatures of the body of water. From June to September, the stream is on average 6 °C warmer downstream than upstream when the pond is full and 0.8 °C when it is dry. The diurnal minima are increased the most downstream the full pond, but the diurnal maxima are increased the most downstream the dry pond. A natural average gradient of warming of the stream of 0.27°C/100 m is measured from upstream to downstream. Compared with the warming due to the pond over the same distance, it can be assessed that the free evolution of the stream is responsible for 15 % of the warming, the pond causing 85 %. Over a greater distance considering the cumulative impact of a cascade of two ponds, the proportion of the natural evolution of the stream rises to 26 %.