According to the National Drought Mitigation Center, it can be hard to measure drought since it’s difficult to determine when it begins and ends.

The Palmer Drought Severity Index is one example of a widely used index that indicates prolonged and abnormal moisture deficiency or excess. The index is based on an equation that uses precipitation, temperature and soil moisture to calculate drought severity. The result is a number that indicates drought classifications.

Another drought measurement tool is The Standard Participation Index which “shows the actual precipitation compared to the probability of precipitation for various time frames.” A short term drought monitoring tool can be found in the Crop Moisture Index, which is used to monitor moisture in crop-producing regions.

The National Drought Mitigation Center has a drought monitor that is updated on a regular basis. Check that out to see where conditions stand in your region in the United States.

• Phase 1 – Watch: 
  5 to 10 percent shortage (voluntary reductions); During this stage of drought, your city government is likely to explain the drought situation, forecast future actions and suggest voluntary conservation actions.
• Phase 2 – Warning: 
  10 to 20 percent shortage (voluntary or mandatory reductions);Voluntary conservation actions initiated in Phase 1 are ongoing. The city may require that consumers reduce their water consumption by 10-20 percent at this stage.
• Phase 3 – Emergency: 
  20 to 35 percent shortage (mandatory reductions); In order to provide water for everyone, your city government may institute rationing programs by issuing fixed allotments based on per capita or per household data, such as lot size, past usage, or other data. They may also require all homes to have low-flow showerheads and toilet displacement devices or ultra-low flush toilets before granting an increased allotment. In addition, all municipal pools may be required to cover their pools to prevent evaporation.
• Phase 4 – Critical: 
  35 to 50 percent shortage (mandatory reductions); All steps implemented in Phase 3 are likely to intensify, and local law enforcement will monitor for compliance. Outdoor water use may be cut completely.

A line of defense during drought is for utilities to enforce and promote water restrictions. This is done through water rates, municipal ordinances, federal laws and regulations and financial incentives. For example some municipalities:

• offer financial incentives to install efficient plumbing or water efficient landscaping;
• allow the public to water only on certain days by enforcing municipal ordinances; and
• ban fountains unless they run on recirculated water.

In contrast to drought management plans, some cities embrace drought preparedness by putting programs and projects in place now to minimize or avoid drought impacts.

Drought preparedness activities include:

• ongoing conservation programs;
• water reuse applications;
• water storage and management projects, using both surface and groundwater; and
• storing water in aquifers.