Subject
Geology
295
Texas History
149
Water quality
143
Groundwater
127
Geology, Stratigraphic
122
Texas Description and travel
107
Texas
92
Water-supply
85
Frontier and pioneer life
75
Paleontology
68
Hydrogeology
60
Edwards Aquifer (Tex.)
56
Aquifers
52
Post office buildings
46
Stream measurements
45
Water Pollution
41
Streamflow
40
Petroleum
33
Hydrology
31
Mines and mineral resources
31
Groundwater flow
30
Public buildings
29
Floods
26
Natural gas
26
Indians of North America
24
National parks and reserves
24
Petrology
23
Courthouses
22
Texas Politics and government
22
Groundwater Quality
21
Oil fields
21
Auditing
19
Land titles Registration and transfer
19
Uranium ores
19
Texas Annexation to the United States
18
Groundwater Pollution
17
Rules and practice
17
Texas Emigration and immigration
17
Environmental impact statements
16
Historic sites Law and legislation
16
Petroleum Geology
16
Cattle trade
15
History
15
Land grants
15
Trinity Aquifer (Tex.)
15
Water resources development
15
Big Bend National Park (Tex.)
14
Environmental impact analysis
14
Guadalupe Mountains National Park (Tex.)
14
Texas Altitudes
14
more ...