Here is the latest Grand Lake St. Marys monitoring data from the Ohio EPA.
| Celina PWS Intake | 09/12/12 | Microcystins | 32.6 ppb |
| Grand Lake – Windy Point | 09/11/12 | Microcystins | 31.8 ppb |
| State Park Main Beach East | 09/11/12 | Microcystins | 26.4 ppb |
| State Park Main Beach West | 09/11/12 | Microcystins | 33.2 ppb |
| State Park Camp Beach | 09/11/12 | Microcystins | 31.8 ppb |
| USGS Buoy 5 | 09/11/12 | Microcystins | 36.4 ppb |
| USGS Buoy 6 | 09/11/12 | Microcystins | 43.2 ppb |
| USGS Buoy 3 | 09/11/12 | Microcystins | 41.0 ppb |
| USGS Buoy 2 | 09/11/12 | Microcystins | 44.0 ppb |
| USGS Buoy 4 | 09/11/12 | Microcystins | 42.6 ppb |
| USGS Buoy 2 | 09/11/12 | Microcystins | 46.4 ppb |
| Grand Lake – Windy Point | 09/05/12 | Microcystins | 54.4 ppb |
| State Park Main Beach East | 09/05/12 | Microcystins | 51.6 ppb |
| State Park Main Beach West | 09/05/12 | Microcystins | 39.2 ppb |
| State Park Camp Beach | 09/05/12 | Microcystins | 42.6 ppb |
| Celina PWS Intake | 09/05/12 | Microcystins | 64.0 ppb |
| Celina PWS Intake | 08/30/12 | Saxitoxin | Not Detected |