Connecticut 305b Assessed Lake 2020 is a 1:24,000-scale, polygon feature-based layer that includes lakes that have been assessed in compliance with Sections 305(b) and 303(d) of the federal Clean Water Act. Section 305(b) of the Clean Water Act requires each state to monitor, assess and report on the quality of its waters relative to attainment of designated uses established by the State's water quality standards. Section 303(d) requires each State to compile a subset of that list identifying only those waters not meeting water quality standards and assign a Total Maximum Daily Load (TMDL) priority ranking to each impaired waterbody.

This layer is based on information collected and compiled prior to 2020. It represents conditions at a particular point in time and does not represent current conditions. This layer includes only assessed lakes. It can be used with the 2020 Connecticut 305b Assessed River layer and the Connecticut 305b Assessed Estuary layer to geographically display attainment and non-attainment for each designated use on assessed waters within Connecticut's boundaries.

Features are polygon locations that represent the locations of assessed lakes. The sources for these features include the hydrography layer and the water quality classification layer. Attribute information is comprised of the Connecticut lake identification number, a unique identifier for each feature, the name of the waterbody, its location, the assessment cycle (