The Water Cycle: Springs

What is a spring?


A spring is a water resource formed when the side of a hill, a valley bottom or other excavation intersects a flowing body of ground water at or below the local water table, below which the subsurface material is saturated with water. A spring is the result of an aquifer being filled to the point that the water overflows onto the land surface. They range in size from intermittent seeps, which flow only after much rain, to huge pools flowing hundreds of millions of gallons daily.

Springs are not limited to the Earth's surface, though. Recently, scientists have discovered hot springs at depths of up to 2.5 kilometers in the oceans, generally along mid-ocean rifts (spreading ridges). The hot water (over 300 degrees Celsius) coming from these springs is also rich in minerals and sulfur, which results in a unique ecosystem where unusual and exotic sea life seems to thrive.

How are springs formed?

Springs may be formed in any sort of rock. Small ones are found in many places. In Missouri, the largest springs are formed in limestone and dolomite in the karst topography of the Ozarks. Both dolomite and limestone fracture relatively easily. When weak carbonic acid (formed by rainwater percolating through organic matter in the soil) enters these fractures it dissolves bedrock. When it reaches a horizontal crack or a layer of non-dissolving rock such as sandstone or shale, it begins to cut sideways, forming an underground stream. As the process continues, the water hollows out more rock, eventually admitting an airspace, at which point the spring stream can be considered a cave. This process is supposed to take tens to hundreds of thousands of years to complete.

Water flow from springs

The amount of water that flows from springs depends on many factors, including the size of the caverns within the rocks, the water pressure in the aquifer, the size of the spring basin, and the amount of rainfall. Human activities also can influence the volume of water that discharges from a spring—ground-water withdrawals in an area can reduce the pressure in an aquifer, causing water levels in the aquifer system to drop and ultimately decreasing the flow from the spring. Most people probably think of a spring as being like a pool of water—and normally that is the case. But, as this picture of the wall of the Grand Canyon in Arizona, USA shows, springs can occur when geologic, hydrologic, or human forces cut into the underground layers of soil and rock where water is in movement.

Spring water is not always clear

Water from springs usually is remarkably clear. Water from some springs, however, may be "tea-colored." This picture shows a natural spring in southwestern Colorado. Its red iron coloring and metals enrichment are caused by ground water coming in contact with naturally occurring minerals present as a result of ancient volcanic activity in the area. In Florida, many surface waters contain natural tannic acids from organic material in subsurface rocks, and the color from these streams can appear in springs. If surface water enters the aquifer near a spring, the water can move quickly through the aquifer and discharge at the spring vent. The discharge of highly colored water from springs can indicate that water is flowing quickly through large channels within the aquifer without being filtered through the soil.
This water is cold and clear—is it fit to drink?

The quality of the water in the local ground-water system will generally determine the quality of spring water. The quality of water discharged by springs can vary greatly because of factors such as the quality of the water that recharges the aquifer and the type of rocks with which the ground water is in contact. The rate of flow and the length of the flowpath through the aquifer affects the amount of time the water is in contact with the rock, and thus, the amount of minerals that the water can dissolve. The quality of the water also can be affected by the mixing of freshwater with pockets of ancient seawater in the aquifer or with modern seawater along an ocean coast.


So, should you feel confident about whipping out your canteen and filling it with cool and refreshing spring water? No, you should be cautious. The temperature of an Ozark spring comes from its passing through rock at a mean annual temperature of 56 degrees Farenheit. The water is crudely filtered in the rock, and the time spent underground allows debris and mud to fall out of suspension. If underground long enough, lack of sunlight causes most algae and water plants to die. However, microbes, viruses, and bacteria do not die just from being underground, nor are any agricultural or industrial pollutants removed. By the way, no, this man is not getting a drink from this tempting spring. He is a USGS hydrologist sampling the near-boiling water from a spring in Wyoming.

Water Effect Videos

Public gets another look at Spokane River Water Quality

The Washington Department of Ecology (Ecology) has made substantial changes to the draft water-quality improvement plan to restore dissolved oxygen in the Spokane River and Lake Spokane, warranting a new public review period.

The new comment period opens today and continues through Oct. 15, 2009. The Spokane River/Lake Spokane Dissolved Oxygen Water Quality Improvement Plan, often referred to as the total maximum daily load (TMDL) report, will guide work toward a healthier Spokane River in compliance with water quality standards for dissolved oxygen.

A public meeting is planned for 6-9 p.m., Thursday, Sept. 24, 2009, at the Spokane Community College’s Sasquatch Room in the Lair Building #6, 1810 N Greene St., Spokane.


“This document has been controversial and the subject of many years of community discussion,” said Water Quality Program Manager Kelly Susewind. “We heard the community’s concerns during the previous public comment period and we have worked hard on this draft plan to address those concerns. Now it’s time to take one more look.”

The water quality improvement plan outlines how the community will reduce phosphorus and other substances in the Spokane River and Lake Spokane to prevent algae blooms, increased growth of aquatic plants and the related declines in Lake Spokane’s dissolved oxygen. Under the federal Clean Water Act, when a body of water fails to meet water quality standards for certain pollutants, Ecology must study the problem and produce a plan to improve water quality.

Phosphorus is the primary nutrient causing excess algae and plant growth in the Spokane River and Lake Spokane. It behaves like fertilizer, causing algae and other aquatic plants to grow and thrive. When the plants decompose, they use up dissolved oxygen that fish need to breathe. More algae means less oxygen.

In addition, unsightly algae blooms can become toxic and cause nuisance smells or human skin irritations. They can make Lake Spokane unhealthy for swimming, and compromise its ecological balance.

The Spokane River / Lake Spokane Dissolved Oxygen Water Quality Improvement Plan will lead to reducing phosphorus pollution from industrial and municipal pipes by more than 90 percent. Its phosphorous limits for industrial and municipal discharges are among the most stringent in the country.

Unique to this improvement plan, the industrial and municipal “point-source” (from a pipe) dischargers are required to help reduce phosphorus from other diffuse, “non-point” sources as well. Non-point sources include farms, septic systems, stormwater runoff, animal waste, and fertilizers used at home. In addition, the plan gives Avista Corp., operator of Long Lake Dam, a portion of the responsibility to improve dissolved oxygen levels in Lake Spokane.

The U.S. Environmental Protection Agency (EPA), working with Ecology, the Idaho Department of Environmental Quality and the Spokane Tribe of Indians hired experts at Portland State University to conduct new computer modeling after the EPA changed its procedures in 2008. Instead of measuring “background” levels of phosphorus and other nutrients at the Idaho/Washington border, EPA reversed course and said background levels used should be from Lake Coeur d’Alene, miles upriver.

This change in course changed the numbers used to calculate how much phosphorus each industry and municipality along the river is allowed to discharge on both sides of the state line. Changes were made in the water quality improvement plan based on the new course, new computer modeling and two prior public comment opportunities in the past two years.

Water quality models are mathematical tools that are used to represent a water system. By entering all the data into a model, scientists can visualize, predict, and determine water quality factors that may be causing pollution. They can see what the river’s levels of phosphorus might be under different scenarios, and from there, good decisions can be made.

USGS will track cause and extent of ground sinking near California Aqueduct

Historically, extensive pumping of groundwater from the San Joaquin Valley aquifer system caused groundwater levels to decline, resulting in as much as 28 feet of land subsidence. The importation of surface water to the San Joaquin Valley in the 1970s reduced demand for groundwater, resulting in a recovery of groundwater levels and a reduced rate of land subsidence.

Groundwater pumping in the Valley has increased in recent years as drought and fish-protection measures have curtailed surface-water deliveries.

for more information http://www.usgs.gov/newsroom/article.asp?ID=2300

NOAA Report Explains Sea Level Anomaly this Summer along the U.S. Atlantic Coast

Persistent winds and a weakened current in the Mid-Atlantic contributed to higher than normal sea levels along the Eastern Seaboard in June and July, according to a new NOAA technical report.

After observing water levels six inches to two feet higher than originally predicted, NOAA scientists began analyzing data from select tide stations and buoys from Maine to Florida and found that a weakening of the Florida Current Transport—an oceanic current that feeds into the Gulf Stream—in addition to steady and persistent Northeast winds, contributed to this anomaly.

“The ocean is dynamic and it’s not uncommon to have anomalies,” said Mike Szabados, director of NOAA’s Center for Operational Oceanographic Products and Services. “What made this event unique was its breadth, intensity and duration.”

The highest atypical sea levels occurred closer to where the anomaly formed in the Mid-Atlantic, where cities like Baltimore, Md., at times experienced extreme high tides as much as two feet higher than normal. Data from NOAA’s National Water Level Observation Network tide stations, Atlantic Oceanographic and Meteorological Laboratory, and National Data Buoy Center, are published in the report.

Impacts of the event were amplified by the occurrence of a perigean-spring tide, the natural timing of the season and month when the moon is closest to the Earth and its gravitational pull heightens the elevation of the water. The combined effects of this tide with the sea level anomaly produced minor flooding on the coast.

“The report is a good first assessment,” said NOAA Oceanographer William Sweet, Ph.D. “However, NOAA, with our academic partners, should continue to investigate the broader causes behind the event. Further analysis is needed to fully understand what is driving the patterns we observed.”

Article source: http://www.noaanews.noaa.gov/stories2009/20090831_tides.html