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.

Rain brings increases in spring flow and groundwater levels
November 2021 Hydro Report

The wet conditions this Fall have boosted spring flow at area Middle Trinity springs.  Flow in the Blanco River peaked at 9,210 cfs on Oct. 14.  After runoff subsided, springs continue well above previous baseflow conditions.  Pre-rain conditions at Pleasant Valley and Park Springs on the Blanco River upstream of Fischer Store Road saw an increase in baseflow from 16 cfs to nearly 22 cfs.  Baseflow at Jacob’s Well increased from 2-3 cfs to just below is about 20 cfs.

Groundwater levels and spring flow fluctuate through time. Rainfall and pumping are the biggest factors influencing aquifer conditions. The Texas Water Development Board, in conjunction with many groundwater conservation districts, maintains monitor wells throughout the state (the data are publicly accessible on this web link). The water level in the Mt. Baldy monitor well (Middle Trinity) has responded to the influx of recharge.  Oftentimes, groundwater levels are slower to respond than spring flow, and the Mt. Baldy well measurements show only a slight delay, which shows the highly developed flowpaths within the Middle Trinity karst system.  Water level rise plateaued and has begun to decline again with lack of additional rain.

Mt Baldy Monitor Well – 30 day view hydrograph.
Mt. Baldy Monitor Well – Period of record view

While we can’t control the weather, we can conserve water and look for innovative ways to use alternate supplies (like site-harvested supplies—rainwater and AC condensate) to lessen impacts of pumping. Typically, the high water use period extends from May 1 – September 30. Less pumping and continued wet conditions could create much needed recharge and boost water levels and spring flow. While each aquifer behaves differently, all groundwater is limited and deserves to be used wisely. For more information on native landscapes, rainwater harvesting, leak identification tips and more, visit the Home Owner Resource page.

No matter what area agencies call their drought declaration, coordinated water conservation is important to preserve groundwater availability, spring flow, and water supplies.

Agency Drought Stage Date Declared Details
Hays Trinity GCD Jacob’s Well GMZ – 20% Curtailment
Remaining GCD – No Drought		 Jun. 2021 Board Order, 6/3/2020
Barton Springs Edwards Aquifer CD No Curtailment Jul. 2021 Press Release, 7/8/2021
Edwards Aquifer Authority No Curtailment May 2021 Press Release, 5/7/2021

[Updated 11/14/2021]

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 Nov Rain brings increases in spring flow and groundwater levels 19.2 cfs 22.5 cfs 11/14/21
2021 Oct Rain brings temporary increases in spring flow and groundwater levels 2.7 cfs 16.0 cfs 10/7/21
2021 Sept Water levels and spring flow on the decline (again) 2.6 cfs 28.1 cfs 9/16/2021
2021 July Spring flow increased, Groundwater levels still low 3.9 cfs 33.2 cfs 7/6/2021
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.