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.

Recharge!
May 2021 Hydro Report

Welcome rains have saturated soils and allowed runoff.  That runoff has translated into recharge as water makes its way through karst features like caves and sinkholes into the groundwater system.  Once the recharge creeks start flowing, recharge reaches the aquifers quickly with little filtration.

The graph above shows flow at two Middle Trinity springs–Jacob’s Well and Pleasant Valley.  These springs provide the baseflow for Cypress Creek and the Blanco River in western Hays County, respectively. The 3-4″ rainfall totals at the beginning of the May contributed good recharge to the groundwater system.  Jacob’s Well flow momentarily peaked at about 30 cfs, Pleasant Valley and Park Springs temporarily reached 17 cfs. Spring flow has slightly increased even after the rainfall ended, which indicates that recharge added water to the groundwater system. We’ll see a similar response to the hydrographs with the next round of rain.  The water level in the Mt. Baldy Monitor Well has leveled off, and with additional recharge may begin to increase.

NOAA has forecast significant rainfall for late May.  Additional rains this week are expected to generate a lot more runoff, and therefore, more recharge.  With runoff comes the potential for high water in area creeks and rivers.  Be cautious when driving over low water crossings–check for water over the road.  Turn around, don’t drown.

Image credit: NOAA

No matter what area agencies call their drought declaration, it’s obvious water levels and spring flows remain low. 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 No Curtailment May 2021 Press Release, 5/7/2021

[Updated 5/18/2021]

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 May Recharge! 2.2 cfs 13.5 cfs 5/18/2021
2021 April Lowest Groundwater Level Recorded Since 2005 1.4 cfs 11.4 cfs 4/22/2021
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.