Various elements of the pore water of Lake Kinneret sediments have been analyzed and their fluctuations observed during 20 months at four stations, with concomitant measurements of bottom currents, temperature, and benthic flora. Dissolved iron reaches its maximum solubility at the beginning of turnover. The exchangeable phosphorus seems to be the iron‐bound fraction and its concentration in the pore water increases simultaneously with the reduction of sulfates and precipitation of iron sulfide, but its release is controlled by the calcium phosphate equilibria. This mechanism explains how the rate of release of phosphorus is only 0.8 mg m−2 day−1 and how the Kinneret sediments play the role of a sink as far as phosphorus is concerned. Ammonia is produced by an intense process of ammonification and its rate of release reaches 25 mg m−2 day−1. The internal nutrient load is compared to the external one. Since there is evidence that the winter‐spring Peridinium bloom can be supported solely by the internal load, working hypotheses are provided concerning the relationship between the release of nutrients from the mud and the nature of the bloom.