Environmental factors can affect organic matter inputs and the structure of aquatic invertebrate assemblages in streams. This study evaluated the effects of upstream agriculture on leaf patches and associated invertebrate assemblages in low-order streams. We sampled leaf patches formed on the substrate of forest reaches located downstream and upstream of agricultural areas. We hypothesized that agriculture would negatively affect leaf patches' biomass and species richness, changing the structure of associated invertebrate assemblages. We found a positive correlation between leaf biomass and total invertebrate abundance. The abundance and richness of Ephemeroptera, Plecoptera, and Trichoptera (EPT) were also correlated with leaf biomass. Invertebrate abundance was higher in reaches located downstream agricultural areas. The taxonomic composition of invertebrate assemblages differed between reaches located downstream and upstream agricultural areas. However, agriculture did not affect leaf patches' biomass and species richness. Our findings demonstrated that changes in land use caused by agriculture can also affect invertebrate assemblages in forest reaches located downstream. Understanding and managing riparian areas is essential for maintaining the biodiversity and functionality of stream ecosystems.