The data were gathered as a preliminary assessment of estrogenicity under base-flow conditions at over 100 sites (lakes and streams) throughout New Jersey followed by more targeted sampling of smallmouth bass at nine sites with varying levels of estrogenicity. In 2016, 102 sites (lakes and streams) for the preliminary estrogenicity assessment were selected utilizing compiled results of previous monitoring studies (chemical and biological), current sampling networks, and other areas of concern based on input from stakeholders. Discrete grab surface water samples were collected under base-flow conditions in the fall of 2016 and analyzed for levels of estrogenicity using a bioluminescent yeast screen. Water samples for estrogenicity were also collected from the nine health sites in April/May of 2017 in combination with fish sampling and again in November 2017 under base flow conditions. In the spring of 2017, 20 adult smallmouth bass were collected from each of the nine sites (two river and seven reservoir sites). Fish were collected by boat electroshocking, euthanized in the field, weighed, measured, a blood sample collected and a necropsy completed that included documenting any visible abnormalities and collecting tissues for histopathology. Plasma obtained from blood samples was analyzed for vitellogenin, a yolk precursor widely used as an indicator of estrogenic exposure in immature and male fishes. Five to seven sections of testes were processed for microscopic analyses, embedded in paraffin, sectioned at 5 µm, stained with hematoxylin and eosin. The presence of testicular oocytes was noted and the severity rated from 1 to 4 based on number and arrangement of oocytes.