As of the first days of 2013, the CBP Border Patrol along the Rio Grande River in South Texas appears to have migrated over to new frequencies and P25 digital radios.
According to some postings on Radio Reference, here are some of the new Border Patrol operational channels near Brownsville, Texas;
162.2875, NA50
163.0625, NA40
163.4750, NA61
163.5250, NA10
163.6500, NA60
163.9750, NA21
164.4375, NA51
164.7375, NA41
166.9875, N310
168.3875, N312
169.2625, N293 - CBP Air 3
169.5750, NA80
169.6000, NA20
169.6375, NA31 - Weslaco 2
169.6625, NA30 - Weslaco 1
170.1250, NA40
170.3375, NA50
170.4375, NA61
170.5375, NA40 - Harlingen 1
170.9875, NA60
171.1875, NA20 - McAllen
171.1875, NB20
171.3250, NA11 - Rio Grande City 2
171.3250, NA41 - Harlingen
171.6625, NA12 - Rio Grande City 1
171.6625, NA51
171.7125, NA22 - McAllen 2
171.9625, NA10 - Rio Grande City (?)
171.9875, N311
172.2375, NC20
172.2625, NA21 - McAllen 1
172.7125, NA60