## 
## Stratum: None 
## Initial number of levels: 4 
## Current number of levels: 4 
## Current number of levels: 5 
## Final number of levels: 5 
## 
## Stratum: None 
## Initial number of levels: 4 
## Current number of levels: 4 
## Current number of levels: 5 
## Current number of levels: 6 
## Final number of levels: 6

A grid of possible sample points was created by identifying all plots sampled from 1989 - 2004 but eliminating “duplicate” points within 300 m of each other. This resulted in a grid of 305 potential sampling locations. Applying a GRTS draw to these locations, separately for each basin, the plots to be sampled (red points) under various effort schemes is illustrated below for samples of 100, 150, 200, and 250 points.