WaterML 2.0 is a candidate Open Geospatial Consortium standard for the representation of hydrological observations, specifically addressing time series data. The WaterML 2.0 candidate standard is implemented as an application schema of the OGC Geography Markup Language (GML) Encoding Standard
version 3.2.1 and makes use of the OGC Observations and Measurements (O&M)  model and encoding standards.

The OGC WaterML 2.0 candidate standard supports encoding of hydrological and hydrogeological observation data in exchange scenarios such as: exchange of data for operational monitoring and forecasting programs; supporting operation of infrastructure (e.g. dams, supply systems); exchange of observational and forecast data for surface water and groundwater; release of data for public dissemination; enhancing disaster management through data exchange; and exchange in support of national reporting.

WaterML 2.0 is the result of an international cooperative effort of the OGC Hydrology Domain Working Group , involving hydrological and government agencies, software providers, universities and research organizations from Australia, the USA, Canada, Germany, the Netherlands and other countries.

The candidate OGC WaterML Version 2.0 standard documents are available for public review and comment.  Comments are due by 17 February 2012.