Water Coverage and Aquifers

Water Coverage and Types

• 71% of the 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
• Largest surface water rights holders: The Dow Chemical Company, Entergy Texas, Inc., and City of Clyde

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

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

Water and Watersheds

• A watershed is a land area that drains water to a particular stream, river, or lake
• It can be identified by tracing a line along the highest elevations between two areas on a map, often a ridge
• Large watersheds, like the Mississippi River basin, contain thousands of smaller watersheds

Water Supply

• Public water suppliers provide water for domestic, commercial, thermoelectric power, industrial, and public water users
• Most people's household water is delivered by a public water supplier
• The systems have at least 15 service connections or regularly serve at least 25 individuals daily for at least 60 days out of the year

Water Terminology

• CFS (Cubic Feet per Second) is a rate of water flow, equal to a volume of water one foot high and one foot wide flowing a distance of one foot in one second
• Conveyance loss is water lost in transit from a pipe, canal, or ditch by leakage or evaporation
• Drainage basin is a land area where precipitation runs off into streams, rivers, lakes, and reservoirs
• Consumptive use is a part of water withdrawn that is evaporated, transpired by plants, incorporated into products or crops, consumed by humans or livestock, or otherwise removed from the immediate water environment
• Evapotranspiration is the sum of evaporation and transpiration
• Tributary is a smaller river or stream that flows into a larger river or stream
• Turbidity is the amount of solid particles suspended in water that cause light rays to scatter
• Flood plain is a strip of relatively flat and normally dry land alongside a stream, river, or lake that is covered by water during a flood
• Flood stage is the elevation at which overflow of the natural banks of a stream or body of water begins

Waterborne Diseases

• Giardiasis is a disease caused by drinking water that is not filtered or chlorinated, resulting in abdominal discomfort, nausea, and alternating constipation and diarrhea
• Cryptosporidiosis is a diarrheal disease caused by the microscopic parasite Cryptosporidium, resulting in watery diarrhea, stomach cramps, dehydration, nausea, vomiting, fever, and weight loss

Water Quality Standards

• Maximum Contaminant Level (MCL) is the greatest amount of a contaminant that can be present in drinking water without causing a risk to human health
• MCL is designated by the U.S. Environmental Protection Agency (EPA) to water-quality standards promulgated under the Safe Drinking Water Act