Greetings!
This is the first bulletin in a series of bulletins on groundwater. The purpose is to inform you about groundwater and surface water issues in our region so that you can be an informed voice in decisions being made about our water future. Links are made to the Environmental Stewardship website which will provide more in-depth local information, or the Texas Water Matters website which covers the breadth of these issues throughout Texas. These sources provide more information for those who want to dig deeper. Or feel free to contact me directly.
Don't miss the Groundwater Marketing Seminar being sponsored by the Pines & Prairies Land Trust (see right column).
The next bulletin will discuss water management in Texas and our region.
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Groundwater & Surface Water - What's the difference?
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There are two types of water characterized by the Texas legislature and water planners: Groundwater and Surface Water.
Surface Water - When a raindrop strikes the land it is "surface water" as it runs through ditches, creeks, streams and rivers or is stored in lakes, reservoirs, tanks or ponds. Surface waters interact with groundwater in many ways. Our primary interest is in the way groundwater provides water to rivers and streams.
Springs - Groundwater becomes surface water the minute it hits the surface of the land or enters a surface water feature such as a river.
Groundwater - When the water soaks into the soil and is stored below the surface of the land, it is groundwater. Groundwater is stored between the mineral particles (dirt or sand) or in caves and caverns much like underground lakes. These underground storage units are called "aquifers".
Aquifers - Aquifers are large underground areas of water storage. They get their water from the rainwater that penetrates the surface and accumulates in these storage areas, a process known as "recharge", or from the migration of water from one aquifer to another. All aquifers are not alike. This is very important to Central Texas because we have two very different types of aquifers. The Edwards Aquifer is very different from the Carrizo-Wilcox aquifer. The key differences, for our consideration, are the rate of recharge and artesian pressure.
Recharge - As water penetrates the surface of the earth and migrates down through the layers it recharges, or refills, the aquifer. Some aquifers, like the Edwards Aquifer, recharge RAPIDLY. Because the water is stored in large caverns that have large openings to the surface of the earth, these aquifers can be refilled quickly; with one or a few significant rainfall events. Other aquifers, like the Carrizo-Wilcox are VERY SLOW to recharge; taking tens or even thousands of years. Because the water is stored between the sand particles it takes a very long time for the water to penetrate through the soil to the storage area. Likewise, the movement of water from one aquifer to another is measured in feet-per-year. It is estimated that the Carrizo-Wilcox recharges at a rate of only 3-5% of the total rainfall that falls on the recharge zone.
Artesian Aquifers - An artesian aquifer is a confined aquifer whose water is pressurized. Water will thus flow out of an artesian well or spring without pumping. The Carrizo-Wilcox aquifer is an artesian aquifer. The artesian pressure is created by the confined space where the majority of water is stored. As water is removed from the confined space, the amount of artesian pressure is reduced, and the volume of flow to the surface is reduced.
Artesian Springs - Springs that flow to the surface due to the pressure from the confined portion of the aquifer are "artesian springs". The volume of flow to the surface depends on the artesian pressure. Many of these springs emerge at the bottom of lakes, rivers and streams and, therefore, are not easy to observe. These springs provide "base-flow" to surface water features.
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Gaining River may become Losing River
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The Colorado River and many streams in the Lost Pines Region "gain" water from the Carrizo-Wilcox Aquifer as they cross over the aquifer in Bastrop County; the Colorado River is a gaining river in this reach. Studies estimate that the Colorado River gains about 25,000 acre-feet/year of water from the Simsboro formation as it crosses the aquifer between Utley (FM 969 bridge) and Bastrop. That is about 81 million gallons of water. The Simsboro formation is the portion of the aquifer where water planners and water marketers plan to take water to be exported to other parts of Texas.
Losing (left) and Gaining (right) Streams  | Because the Carrizo-Wilcox is an artesian aquifer, it releases water to the surface when it is full. It is estimated that it releases about 1-2% of the total amount stored to rivers, streams and springs.
Modeling studies by the Lower Colorado Region Water Planning Group (Region K) estimate that the Colorado River will become a "losing" river by about 2050 due to heavy pumping planned for the Carrizo-Wilcox aquifer.
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Issues of Concern - Over-pumping impacts on rivers, streams and springs.
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The quantity of groundwater supplied to the Colorado and Brazos rivers and streams by the Carrizo-Wilcox and related aquifers declined by 50% while pumping increase 31%. The data was presented Bill Hutchinson of the Texas Water Development Board to the Lost Pines Groundwater Conservation District (November 18, 2009). The pink line to the right shows the decline in water that supplied the Colorado and Brazos rivers, streams and springs in Groundwater Management Area 12 during the period from 1980 to 1999. The dark line is the increased pumping during the same period. This signals a significant change in the relationship between groundwater
and surface water. Decisions will be made over the next year that will have long-range consequences that are not easily reversed. The anticipated impact on the Colorado River is likely a predictor of a significant change in the ecological relationships as over-pumping accelerates in the region over the next 20-50 years. For more information click here |
Groundwater Permit Moratorium
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The Lost Pines Groundwater Conservation District recently extended its moratorium on new well permits until they have approved desired future conditions, managed available groundwater, and a management plan to implement these conditions. Environmental Stewardship applauds this positive move by the Lost Pines Groundwater Conservation District. Click here for full text of the moratorium resolution. The moratorium does not affect exempt wells in the district that are used by landowners for their own irrigation and personal consumption.
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Environmental Stewardship Notes |
HELP WANTED: Mowing and maintenance contract for Lost Pines Nature Trails. Must have your own equipment. We are interested in bids for mowing and trash removal for the main picnic area, entry roadway and river access area through the summer and fall seasons. Click here to respond.
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Sincerely,
Steve Box
Executive Director
Environmental Stewardship
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2009 Annual Report
Released
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Environmental Stewardship is pleased to provide its 2009 Annual Report covering activities, initiatives and a financial summary.
Click here to download a PDF of the full report
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Groundwater Marketing
Seminar
April 23
1-5 pm
Click for link to flyer
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Sponsored by the Pines & Prairies Land Trust
For more information
contact Carrie Knox
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Our Mission
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Environmental Stewardship is a charitable nonprofit organization whose purposes are to meet current and future needs of the environment and its inhabitants by protecting and enhancing the earth's natural resources; to restore and sustain ecological services using scientific information; and to encourage public stewardship through environmental education and outreach.
We are a Texas nonprofit 501(c) (3) public charity headquartered in Bastrop, Texas.
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How To Participate
Be a Good Steward
Stay Informed
Be Involved
Make a Donation
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