Estrogen occurrence and persistence in vernal pools impacted by wastewater irrigation practices

•Three vernal pools impacted by wastewater irrigation were sampled for estrogens.•A sampling period from April to June 2015 coincided with amphibian metamorphosis.•Estrogens persisted throughout the study period and were in nearly 100% of samples.•Only E1 was in the wastewater, yet E1, 17α-E2 17β-E2, E3 and EE2 were in the ponds.•Estrogens were observed at low levels (>1 ng/L) known to impact aquatic ecosystems.