In this paper I studied the occurrence and distribution of zoosporic true fungi (Blastocladiomycota) and heterotrophic straminipiles (Hyphochytriomycota and Oomycota) from the water of three springs of the Biała River (Sobolewo, Dojlidy Górne, and Kurjany springs) in the vicinity of Białystok. Twenty-one species of zoosporic true fungi and heterotrophic straminipiles belonging to 10 genera of the orders Blastocladiales, Hyphochytriales, Pythiales, and Saprolegniales were isolated using hemp seeds and snake skin as baits. The most commonly encountered species were: Achlya apiculata, Aphanomyces laevis, Catenophlyctis variabilis, Dictyuchus monosporus, Pythium debaryanyum, and Saprolegnia ferax. The highest species richness (S), the largest, and relative frequency (RF) were noted from springs Dojlidy Górne (S=16, RF=76.19%) and Kurjany (S=13, RF=61.90%), whereas the lowest richness and frequency were obtained from Sobolewo (S=9, RF=42.85%).