Human Activity and Ground Water How does human

Human Activity and Ground Water How does human activity change our water systems?

WHAT IS GROUNDWATER? Water that is found underground in the cracks and spaces in soil, sand rock. Half of everyone in the United States gets their water from groundwater Groundwater comes from rain, snow, sleet, and hail that soaks into the ground Groundwater is stored in the ground in materials like gravel and sand

AQUIFERS A body of porous rocks that allows water to saturate and easily flow through is an aquifer. An underground “storehouse” of water is called an aquifer.

WHAT IS A WATERSHED? A watershed is the area of land where all of the water that is under it or drains off of it goes into the same location

WHAT AFFECTS WATERSHEDS? Natural Events: Storms, fires and droughts can suddenly alter watershed conditions Human activity: Point source pollution is pollution that can be traced to a specific point such as a disposal site or leaking pipe. Nonpoint source pollution occurs when pollutants are found when water runs off of areas such as parking lots or crop lands Reduction of the amount of water flowing within a watershed About 40 percent of the lakes in the United States are not clean enough to be used by humans

HUMAN IMPACT ON GROUNDWATER Overuse: groundwater is often withdrawn for agricultural, municipal and industrial purposes. Pollution: contaminants released to the ground that work their way down into groundwater Misuse of fertilizers or manure Leakage from underground storage containers and landfills Run-off from urban areas Construction sites Parking lots

TEXAS WATER ISSUES Rangelands are the major source of water for human use Availability is directly related to the amount & intensity of rainfall Typically, below EPA standards for water quality Traditionally managed for wildlife, livestock, and environmental impact, but not water use

TEXAS WATER ISSUES CONTINUED Water demand currently exceeds supply in many areas Population is expected to double by 2050 - water use will continue to increase May cause changes in water law and private and public property rights

HOW DOES NATURE CLEAN WATER? When water soaks into the ground it moves through soil and rock. The tightly packed particles that make up the soil filter out impurities. Certain ecosystems, such as wetlands, are especially good natural filters, absorbing excess nutrients such as nitrogen or phosphorous from the water.

WHERE DOES WATER COME FROM? When you get water from a faucet where does it come from? All water comes from one of two places: Ground Water Surface Water Where does your city get its water?

GROUND WATER Ground water is water that is below the ground in places called aquifers. An aquifer is a layer of permeable, water-holding gravel or sand beneath the earth’s surface. On top of that layer is a layer of impermeable rock. Can you name a well known aquifer located in Central Texas?

PERMEABLE AND IMPERMEABLE ROCK A permeable layer is a layer of the ground that holds water and allows it to flow freely. An example of a permeable layer is gravel or sand. An impermeable layer is a layer of the ground that does not hold water and does not allow it to pass. An example of an impermeable layer is clay.

How an Aquifer Works Well Water from the aquifer is obtained by digging a well to the level of the water and then drawing it out often by a pump. Top Soil Impervious Layer (clay) Water Table Aquifer The water table is the upper limit of the aquifer. Permeable Rock (sand or gravel) More Clay water

Ground Water Dangers There are many dangers in obtaining water from the ground. • Arsenic is a dangerous element which can be leached from the ground if an aquifer is drawn from too much. • Other contaminants such as lead or nitrates can soak into the aquifer by rain water from landfills.

Subsidence Another big problem with getting water from the ground is subsidence. As water is removed from the ground sinks, or subsides, which causes problems for buildings and eventually flooding in some cities. This is an illustration of a city on a lake which gets its water from the ground. Once the city sinks below the level of the lake there is nothing to stop the lake from flooding the city. If this city used water from the lake it would not face this problem.

Surface Water • Surface water is any water found on the surface of the earth such as reservoirs, lakes, rivers, oceans, and other. • The majority of surface water is not drinkable because it is mostly salt water. • Lakes, rivers, and reservoirs are the best sources of fresh water. • What are some sources of surface water near you?

How a Reservoir Works Reservoirs are manmade lakes often made from damming a river or other water source. Reservoirs are built to retain more water to provide the people nearby with enough drinking water. Runoff is water that falls on a higher elevation in the form of snow or rain then flows down to the reservoir. Runoff from mountains supplies reservoir with fresh water Manmade Reservoir

Surface Water Dangers • Surface water is more easily contaminated because it is more exposed than ground water. • Contaminants can come from a variety of sources such as factories, landfills, or cities. • Arsenic is not as big a problem for surface water as for ground water, but lead and nitrates can contaminate surface water more easily than ground water.

Droughts can be a major problem for using surface water as a water source. If the source of water is not replenished by rain or runoff it can be drained and disappear. Remember the town from before? This time they use the water from the lake, but do not allow the lake to be replenished. Soon they are left with no water if the water is not replenished by runoff or rain.

Lead is a metal that often contaminates water through old pipes. It can also contaminate surface water if waste containing lead is allowed to sit near the source of water. Lead-Contaminated Runoff Rain Lead Waste Here the water is poisoned by lead-contaminated runoff from a landfill. Lead. Contaminated Reservoir

Arsenic is an element primarily found in ground water. When water is drawn from the ground too quickly arsenic is leached into the aquifer. In this example the city’s water is contaminated by arsenic that has been seeped into the aquifer Arsenic Water

Nitrates are a compound used as pesticides. They are mass-produced in factories and can often contaminate nearby water sources. The factory upstream of the city dumps nitrates into the river. The nitrates contaminate the city’s water supply as they flow downstream. Nitrates

HOW HAVE WE PROTECTED OUR WATER? The Clean Water Act (CWA): Regulates discharges of pollutants into waters Sets wastewater standards for industry Sets water quality standards for all contaminants in surface waters