There are several key players when it comes to water monitoring in the Hill Country.  Each agency publishes data through different platforms and reports.  This page compiles useful references that can help get a more comprehensive view of water resources in the Hill Country.

Lowest Groundwater Level Recorded Since 2005
April 2021 Hydro Report

Fig. 1: In March, groundwater levels in the Mt. Baldy monitor well reached the lowest level recorded since Nov. 2005.

Fig. 2: The water level in the Mt. Baldy well did not recover after the high water use and dry summer in 2020.

Fig. 3: Middle Trinity springs hydrograph

Groundwater, springs, creeks, and rivers are connected in the Hill Country. In March, groundwater levels in the HTGCD Mt. Baldy monitor well, a Middle Trinity Aquifer (Cow Creek) well, reached the lowest level recorded since Nov. 2005 (Fig. 1).  Most of Western Hays County residents rely on either wells or groundwater-supplied water utilities.  Many groundwater conservation districts (see table below for specifics) have declared drought and are enforcing pumpage curtailments to extend water supplies until rainfall can replenish groundwater supplies.

Typically, fall and winter rains generate recharge to replenish groundwater supplies–but the series of small rainfall events during this year’s wet season didn’t create much runoff, and therefore, not much recharge reached our aquifers (Fig. 2).  The exceptionally low water levels in monitor wells reinforces the importance of water conservation while drought conditions persist.

In the Hill Country, spring flow and streamflow are good indicators of groundwater conditions.  Figure 3 shows a hydrograph of baseflow provided by Middle Trinity Aquifer springs in the Blanco River and Cypress Creek correlated with rainfall totals.  As water levels in the aquifer decline, spring flow decreases.

In many ways, we are in the middle of a sneaky drought.  Small rain events have supplied enough water to support surface vegetation, but they haven’t generated enough runoff to recharge area aquifers.  With these dry conditions, rainfall is absorbed by exceptionally dry soils.  After the prolonged dry conditions, it will take several consecutive rains to wet the soils before sustained recharge can refill the aquifers.

On March 23, the EAA weather station near Burnett Ranches measured 0.76 inches and a private weather station in downtown Wimberley measured 0.93 inches of rain.  Given dry soils, this welcome rainfall did little to replenish groundwater supplies.  In western Hays County, baseflow conditions at the Blanco River and Cypress Creek have seen steady declines throughout the fall and winter.

Such low spring flow is an exceptionally troubling condition; however, watching the flow trends for Middle Trinity springs and taking action as key thresholds are crossed mean we as a community can slow groundwater decline and extend supplies.  Springs are a key indicator of groundwater storage and the status of our groundwater supply.

Water conservation now will help extend water resources and protect habitat until enough rain events generate meaningful recharge.  Take a moment to tune up your well and clean your pump house and fix pesky drips and leaks. Be part of the collective solution to protect our shared water supply.

Groundwater Drought Declarations

No matter what area agencies call their drought declaration, it’s obvious water levels and spring flows have declined to exceptionally low levels. In order to preserve groundwater availability, coordinated water conservation measures are essential.

Agency Drought Stage Date Declared Details
Hays Trinity GCD Jacob’s Well GMZ – 30% Curtailment
Remaining GCD – 20% Curtailment		 Nov. 2020 Board Order, 11/1/2020
Barton Springs Edwards Aquifer CD Stage II Alarm Drought (20% Curtailment or more) Oct. 2020 Press Release, 10/9/2020
Edwards Aquifer Authority San Antonio Pool is in Stage 1 – 20% Reduction Apr. 2021 Press Release

[Updated 4/1/2021]

Annual rainfall average for Central Texas is approximately 33 inches per year.  To understand recharge potential, it’s important to track where rain falls, how fast it falls, and how saturated the soils are.  Key rain gages for the area are (upstream to downstream):

Realtime comparison of two key spring flow sites: (USGS gages: Blanco at Fischer Store–08170950 and Jacob’s Well–08170990)

Jacob’s Well Spring, Cypress Creek

Jacob’s Well is a Middle Trinity Aquifer spring that provides the baseflow for Cypress Creek.

    • Realtime data: USGS 08170990 Jacobs Well Spg nr Wimberley, TX
    • Spring flow is a strong indicator of groundwater levels in the Jacob’s Well Groundwater Management Zone (JW GMZ), because low spring flow directly correlates to low well water levels.
    • The 10-day average spring flow is a drought trigger for the HTGCD Jacob’s Well GMZ (Thresholds:  10% Curtailment: below 6 cfs; 20% Curtailment: below 5 cfs; 30% Curtailment: below 3 cfs).
    • Groundwater pumping causes 1 to 1.5 cfs fluctuation in flow and is more evident under low flow conditions.

Pleasant Valley and Park Spring, Blanco River

Pleasant Valley and Park Springs are Middle Trinity Aquifer springs that provide significant baseflow for the Blanco River, especially during dry periods.

The Hill Country’s iconic streams are known for their clear water and rocky bottoms.  Oftentimes, cracks, caves, and faults are visible in stream beds.  When creeks and rivers are flowing, these cracks, caves, and faults channel water from the surface into the groundwater system below.  Streamflow gages are strategically located to help monitor gaining (where springs are found) and losing (where recharge happens) sections of creeks and rivers. Key gages include:

Groundwater monitoring is an art.  TWDB, HTGCD, and BSEACD have extensive monitoring networks.

Key wells from west to east:

Archived Hydro Reports

Month Cypress Creek – Jacob’s Well Blanco River – Pleasant Valley & Park Springs Date Published
2021 March 2.4 cfs 13.5 cfs 3/10/2021
2021 January 0.3 cfs 11.8 cfs 1/19/2021
2020 December 1.3 cfs 16.8 cfs 12/8/2020
2020 November 1.1 cfs 17.1 cfs 11/11/2020
2020 October 1.7 cfs 17.7 cfs 10/25/2020
2020 September 6.5 cfs 25.2 cfs 9/14/2020

 

Please note:  Page under construction.  Please email robingary@wimberleywatershed.org with suggestions or questions.