A thorough understanding of the quantity of water required for various uses is critical for developing sustained use of Ohio's water resources. Sufficient quantities of fresh water are necessary, not only for economic development, agriculture, and recreation, but also for supporting ecosystems. Many programs in government agencies and other organizations use water quantity data and information.

Improving water quantity data and characterization, strengthening cooperation between water management programs, and preparing now for future water quantity issues have been identified as a strategic issue. Many types of water use place quantity demands on Ohio's available water supplies. These uses include natural uses such as stream flows needed to sustain fish and wildlife or infiltration of rainfall needed to recharge aquifers.

Water quantity is also linked to water quality with regards to issues such as pollutant concentration levels, waste water discharge requirements, and anthropogenic impacts associated with rainfall/recharge events. Environmental and climatic conditions play a major role in the demands for and the availability of water supplies. Effective decision making relies on water quantity data and information from both naturally occurring events and human activities. Tracking data and information on droughts, floods, storm water runoff, in-stream flows, ground water recharge, water withdrawals, development related storm drainage, and water diversions is critical. Managing Ohio's water resources for sustained use cannot be successful without the knowledge and understanding of the hydrologic cycle, the myriad of demands on the resource and fluctuation in ground and surface water supplies.

As growth and development continue, more water quantity conflicts will occur and more sophisticated analysis and information will be needed to ensure equitable use and sustainability of the resource.