MONITORING PROGRAM

 

The Hill Country Underground Water Conservation District monitors approximately 120 +/- wells across the county to help evaluate groundwater availability within Gillespie County.  The water level monitoring network started back in the late 1980’s and has been an ongoing process.  The selected wells are representative of the various aquifers within the District.  The measuring schedule is broken into three categories: Ellenburger aquifer, Hensel aquifer and other aquifers comprising the Edwards, Hickory, Cambrian and Precambrian aquifers.  Click below on each category to view water level maps contoured in feet above sea level.

 

Ellenburger Aquifer

Well Distribution, Yield, Recharge and Demand Map

Water Level Maps

 

August 2, 2006

October 5, 2006

November 2, 2006

December 7, 2006

January 5, 2007

February 2, 2007

March 7, 2007

April 4, 2007

May 3, 2007

June 7, 2007

July 6, 2007

August 1, 2007

September 10, 2007

October 4, 2007

November 8, 2007

December 6, 2007

January 3, 2008

February 7, 2008

April 1, 2008

June 5, 2008

August 6, 2008

December 2, 2008

January 8, 2009

February 4, 2009

March 5, 2009

April 3, 2009

May 7, 2009

July 1, 2009

August 4,  2009

September 2, 2009

October 2, 2009

November 4, 2009

March 3, 2010

April 6, 2010

May 4, 2010

June 2, 2010

July 8, 2010

August 4, 2010

September 2, 2010

October 7, 2010

November 4, 2010

December 3, 2010

January 5, 2011

March 3, 2011

April 6, 2011

May 5, 2011

June 8, 2011

August 3, 2011

March & August 2011 Difference

September 8, 2011

Aug. & Sept. 2011 Difference

October 5, 2011

Sept. & Oct. 2011 Difference

November 2, 2011

Oct. & Nov. 2011 Difference

December 9, 2011

Nov. & Dec. 2011 Difference

January 6, 2012

Dec. 2011 and Jan. 2012 Difference

February 8, 2012

Jan. & Feb. 2012 Difference

March 1, 2012

Feb. & March 2012 Difference

April 9, 2012

March & April 2012 Difference

May 2, 2012

April & May 2012 Difference

June 6, 2012

May & June 2012 Difference

July 5, 2012

June & July 2012 Difference

August 2, 2012

 

July & August 2012 Difference

September 6, 2012

August & Sept.  2012 Difference

October 4-8, 2012

Sept. and Oct. 2012  Difference

November 2, 2012

Oct. & Nov. 2012 Difference

December 4, 2012

Nov. & Dec. 2012 Difference

February 8, 2013

Dec. 2012 and Feb. 2013 Difference

March 7, 2013

Feb. & March 2013 Difference

April 2, 2013

March & April 2013 Difference

May 10, 2013

April & May 2013 Difference

June 7, 2013

May & June 2013 Difference

July 3, 2013

June & July 2013 Difference

August 9, 2013

July & August 2013 Difference

September 6, 2013

Aug. & Sept. 2013

Difference

October 2, 2013

Sept. & Oct. 2013 Difference

December 4, 2013

Oct. & Dec. 2013 Difference

January 10, 2014

Dec. 2013 and Jan. 2014 Difference

February 4, 2014

Jan. & Feb. 2014 Difference

March 6, 2014

Feb. & March 2014 Difference

April 2, 2014

March & April 2014 Difference

June 6, 2014

April & June 2014 Difference

July 3, 2014

June & July 2014 Difference

August 8, 2014

July & Aug. 2014 Difference

September 8, 2014

Aug. & Sept. 2014

Difference

October 6, 2014

Sept. & Oct. 2014

Difference

January 6, 2015

 

Oct. 2014 & Jan. 2015 Difference

February 9, 2015

Jan. & Feb. 2015 Difference

March 12, 2015

Feb. & March 2015 Difference

April 6, 2015

March & April 2015 Difference

May 4, 2015

April & May 2015 Difference

June 2, 2015

May & June 2015 Difference

August 5, 2015

June & Aug. 2015 Difference

September 3, 2015

Aug. & Sept. 2015 Difference

October 1, 2015

Sept. & Oct. 2015 Difference

November 4, 2015

Oct. & Nov. 2015 Difference

December 4, 2015

Nov. & Dec. 2015 Difference

January 7, 2016

Dec. 2015 & Jan. 2016 Difference

February 4, 2016

Jan. & Feb. 2016 Difference

March 3, 2016

Feb. & March 2016 Difference

April 6, 2016

March & April 2016 Difference

May 4, 2016

April & May 2016 Difference

June 7, 2016

May & June 2016 Difference

July 7, 2016

June & July 2016 Difference

August 2, 2016

Feb. & March 2017 Difference

April 5, 2017

March & April 2017 Difference

May 4, 2017

April & May 2017 Difference

June 7, 2017

May & June 2017 Difference

July 7, 2017

June & July 2017 Difference

 

The Ordovician age Ellenburger aquifer is measured usually once a month in a network of approximately 35 wells.  It is a fractured limestone and dolomite and is present in the southeastern and northwestern portions of the county.  It is absent in a broad area extending from the north central portion of the county continuing to the south, southwest part of Gillespie County.  This is a faulted uplifted area where the Ellenburger and other older Paleozoic rocks were eroded prior to Cretaceous sea transgression and subsequent Hensel deposition.  The area is termed “the Fredericksburg High” in the TWDB Report 339 “Evaluation of the Groundwater Resources of the Paleozoic and Cretaceous Aquifers in the Hill Country of Central Texas”.   In some areas significant cavity development has occurred within the Ellenburger resulting in it being able to produce very large amounts of groundwater (>500 gpm) in some locations.  It is utilized extensively by the City of Fredericksburg and many peach and grape growers in Gillespie County.  Recharge to the Ellenburger is mainly through the overlying Hensel. 

 

Hensel Aquifer
Well Distribution, Yield, Recharge and Demand Map
Water Level Maps

July 2006

November 2006

April 2007

July 2007

October 2007

April 2008

July 2008

October 2008

April/May 2009

August 2009

October 2009

April 2010

July 2010

October 2010

April 2011

July 2011

April & July 2011 Difference

Fall 2011

Spring 2012

Fall 2011 & Spring 2012 Difference

Fall 2012

Spring 2012 & Fall 2012 Difference

Spring 2013

Fall 2012 & Spring 2013 Difference

July 2013

Spring 2013 & July 2013 Difference

October 2013

July 2013 & Oct. 2013 Difference

Spring 2014

Fall 2013 & Spring 2014 Difference

Fall 2014

Spring & Fall 2014

Difference

Spring 2015

 

Fall 2014 & Spring 2015 Difference

July 2015

Spring and July 2015 Difference

Fall 2015

July and Fall 2015 Difference

Spring 2016

Fall 2015 & Spring 2016 Difference

 August 2016

Spring & August 2016 Difference

Fall 2016

Fall & Spring 2016 Difference

Spring 2017

Fall 2016 & Spring 2017 Difference

 

The Cretaceous age Middle Trinity Hensel aquifer is measured three times a year in an network of approximately 35 wells.  It is comprised primarily of sand with secondary amounts of clay and silt.  It extends across the majority of Gillespie County, except along the northern border and the northeastern sector of the county where it has been eroded.  The Hensel outcrops in the Pedernales River Valley, but it is in the subsurface where the Edwards Plateau is present.  Yields from the Hensel are generally 10 to 20 gpm and used for rural domestic and livestock demands.  Some drip irrigation occurs from the Hensel for peaches and vegetables.  It is recharged from local precipitation on its outcrop and through the overlying units where it is in the subsurface. 

 

 

Other Aquifers
Edwards Well Distribution, Yield, Recharge and Demand Map
Hickory Well Distribution, Yield, Recharge and Demand Map
Water Level Maps

 

Spring 2005

Fall 2005

Spring 2006

Fall 2006

Spring 2007

Fall 2007

Spring 2008

Fall 2008

Spring 2009

Fall 2009

Spring 2010

Fall 2010

Spring 2011

Fall 2011

Spring & Fall 2011 Difference

Spring 2012

Fall 2011 & Spring 2012 Difference

Fall 2012

Spring 2012 & Fall 2012 Difference

Spring 2013

Fall 2012 & Spring 2013 Difference

Fall 2013

Spring & Fall 2013 Difference

Spring 2014

Fall 2013 & Spring 2014 Difference

Fall 2014

Spring & Fall 2014

Difference

Spring 2015

Fall 2014 & Spring 2015 Difference

Fall 2015

Spring & Fall 2015 Difference

Spring 2016

Fall 2015 & Spring 2016 Difference

Fall 2016

Spring & Fall 2016 Difference

Spring 2017

Fall 2016 & Spring 2017 Difference

 

 

 

 

 The Edwards, Hickory, Cambrian and Precambrian aquifers are measured two times per year in a network of approximately 52 wells.

The Cretaceous age Edwards aquifer within Gillespie County is comprised of limestone and dolomite that is an extension of the Edwards Plateau into Gillespie County from the west.  Yields from the Edwards are generally low (10-20 gpm) and it is used primarily for rural domestic and livestock demands.   Recharge is from local precipitation which occurs on the outcrop. 

 

The Cambrian age Hickory aquifer is comprised of sand, and like the Hensel, it extends across much of Gillespie County except across the northern border where it has been eroded.  Although it is extensive in area, it only produces groundwater along the above mentioned Fredericksburg High.   Along the Fredericksburg High yields from the Hickory vary from very low (5 gpm) to good (>100 gpm).  The City of Fredericksburg has three municipal wells completed in the Hickory.  In the Eckert area the Hickory is used to drip irrigate grapes that are grown on the Hickory outcrop.  Recharge to the Hickory occurs from local precipitation on its outcrop in northeastern Gillespie County and through the overlying units, where it is in the subsurface.  .

 

Some of the rocks from the Cambrian are aquifers on a very local basis within Gillespie County.  These include the San Saba and Welge of the Wilbers formation and the Cap Mountain of the Riley Formation.  The Welge is a sandstone and yields from it are generally low (<20 gpm).  The San Saba and Cap Mountain are both carbonates which also produce generally low yields, however if significant fracturing is present water yields can be very high (>100 gpm).

 

The Precambrian age rocks are for the most part not aquifers, however in a few local areas long the northern edge of the County, some of the granites produce very small amounts of water (<5 gpm).