A city that size probably has several federal agency field offices.
There is nothing in the database or wiki which means you will have to find them yourself.
You will have to search 162-173.2, 173.4-174, 406.1-420 MHz bands in 12.5 kHz steps and see what you find.
Looking at the wiki article Federal (TX) - The RadioReference Wiki, the federal frequencies sections in Common Frequencies - The RadioReference Wiki, and the database sections in other large counties like Federal Scanner Frequencies and Radio Frequency Reference, will give you an idea of what frequencies are used. Many are nationwide assignments and the same ones are often used in many locations.
Don't be surprised if it take a long time before you hear anything.
There is also a slight chance that some federal agencies could possibly have talkgroups on city/county trunked systems.
There is also a sticky thread http://forums.radioreference.com/texas-radio-discussion-forum/186354-texas-federal-government-monitoring.html
I haven't read it recently so some of the links may not work by now.
As far as federal listening goes there really isnt that much to listen. I'll list what I have heard traffic in the past (may not be used today).
163.775 Border Patrol
163.725 Border Patrol
172.15 TSA p25-136 encrypted-heard recently
Frequencies that I have that I have not received but have in my radio
162.7875 Mahon Bldg
The Boll Weevil Eradication program had a freq that was for Lubbock but I dont know what it is/was ,besides it didnt sound exciting enough to put in my scanner.
I posted several years ago a militatry airplane running mock missions over the city and did catch them talking to someone. http://forums.radioreference.com/texas-radio-discussion-forum/260007-air-exercise-lubbock.html
When one of the President Bush's ( #1 I think) came to Lubbock many years ago I heard the Secret Service Service and the thing I most remember is that they where testing radios and called for "Lubbock Base".
There used to be a website called Lubbockradio.net that had some fed freq ,but it is in the internet heaven now.
FireJustin, I know it may be late ,but if you would want some low power freq used at Tech football games ( may be used at other sporting events) I can PM then to you.
After finding some old notes, I did find some more info, these may not be used any more,
149.625- Texas State Guard ( unknown usage)
165.2875-BATF 100.0 DPL
163.775 BP 123.0 DPL
148.15 CAP 100.0 DPL
This is probably obsolete too. In other areas that is now P25 and a repeater input to 170.9625.