Water Coverage and Aquifers

Study Notes

Water Coverage and Types

71% of Earth's surface is covered with water
97% of the water is saltwater, and 3% is freshwater
80% of the freshwater is frozen, and 20% is liquid
Examples of large water reservoirs: Toledo Bend (4.47 million acre-feet) and others (5,000 acre-feet)

Aquifers

9 major aquifers: underground layers of water-bearing permeable rock, rock fractures, or unconsolidated materials
These aquifers provide a large amount of water over a large area
22 minor aquifers: provide a minor amount of water over a large area or a large amount of water over a small area
Important source of water for rural communities
Brackish aquifers: geologic zones within major or minor aquifers with a Total Dissolved Solids of 1,000 to 10,000 parts per million

Water Use in Texas

Total water use in Texas: 14.17 acre-feet
Breakdown: 55% groundwater, 42% surface water, and 3% other sources

Texas Water Policy

Surface water is owned by the state
Prior Appropriations Doctrine and 1967 Water Rights Adjudication Act
Permit system based on 'first in time, first in right'
Administered through Texas Commission on Environmental Quality

Surface Water Rights Holders

Largest surface water rights holders:
- The Dow Chemical Company (4,209,000 acre-feet)
- Entergy Texas, Inc. (1,590,820 acre-feet)
- City of Clyde (1,534,000 acre-feet)
- others

Groundwater in Texas

Groundwater is owned by property owners
Foundational Doctrine: Rule of Capture
Considered a property right
'Law of the biggest pump'
Groundwater rights can be severed and then reserved or conveyed

Limitations to the Rule of Capture

Malicious taking of water to injure a neighbor
Willful or wanton waste of groundwater
Negligent drilling or pumping causing subsidence
Pumping from a contaminated well
Trespassing to pump groundwater

Groundwater Conservation Districts

Purpose: protect property rights, balance conservation and development of groundwater
Use the best available science in conservation and development of groundwater
Rules developed, adopted, and promulgated by a district

National and International Boundary Waters

Surface water governed by interstate and international treaties
Rio Grande Treaty of 1944

Description

Learn about the percentage of water coverage on Earth, types of water, and underground water reservoirs known as aquifers. Discover the distribution of freshwater and saltwater, and explore examples of large water reservoirs.