Subject
Geology
418
Texas
289
Texas History
161
Groundwater
147
Water quality
144
Geology, Stratigraphic
136
Texas Description and travel
107
Water-supply
92
Aquifers
85
Frontier and pioneer life
81
Paleontology
67
Edwards Aquifer (Tex.)
66
Hydrogeology
65
Stream measurements
49
Post office buildings
46
Streamflow
45
Water Pollution
42
Hydrology
35
Mines and mineral resources
34
Petroleum
33
Floods
30
Groundwater flow
30
Water table
30
Public buildings
29
Indians of North America
27
National parks and reserves
27
Natural gas
27
Petrology
23
Courthouses
22
Oil fields
22
Texas Politics and government
22
Groundwater Pollution
20
Groundwater Quality
20
Land titles Registration and transfer
19
Petroleum Geology
19
Uranium ores
19
Auditing
18
Texas Annexation to the United States
18
Environmental impact statements
17
Rules and practice
17
Texas Emigration and immigration
17
Balcones Canyonlands National Wildlife Refuge (Tex.)
16
Big Bend National Park (Tex.)
16
Historic sites Law and legislation
16
Hunting
16
Trinity Aquifer (Tex.)
16
Water resources development
16
Cattle trade
15
Environmental monitoring
15
Land grants
15
more ...