MCLGs for radionuclides are as indicated in the following table:
| Contaminant | MCLG | 
|---|---|
| 1. Combined radium-226 and radium-228 | Zero. | 
| 2. Gross alpha particle activity (excluding radon and uranium) | Zero. | 
| 3. Beta particle and photon radioactivity | Zero. | 
| 4. Uranium | Zero. | 
[65 FR 76748, Dec. 7, 2000]