Scroll towards the bottom of this:
http://www.nj.gov/dep/rules/rules/njac7_9b.pdf
All NJ waters are listed by drainage. They are classified:
TP Trout Production (trout can reproduce).
TM Trout Maintenance (trout dont reproduce, but the water remains cold enough for them to hold over the summer months).
NT Non Trout (no reproduction, no hold over,
..the water gets too warm in the summer).