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.

2022 In Review: Rainfall, Spring Flow, Streamflow, and Groundwater Levels
Jan 2023 Hydro Report

Rainfall

2022 was a dry year.  According to the Watershed Association weather station, the Jacob’s Well area received a total of 16.2 inches of rain for the year.  Historic monthly rainfall records for Blanco, Texas show an annual average of 34.87 inches, which would mean our area is experiencing a 16.3 inch rainfall deficit for 2022.

The 2022 rainfall deficit has lasting effects that will continue into 2023. In the Wimberley Valley Weather Summary for 2022, comparisons for 2015–2022 by Raymond Schiflett, several statistics stand out in terms of the limited recharge the local groundwater systems received (Wimberley View, 1/4/23).  Schifflett reports 0 days of rainfall over 2 inches in 2022. and states that 2022 was the fourth driest year in the past 35 years. Soaking rains saturate soils and allow for runoff–with no runoff, no water can make its way through faults, fractures and caves into the groundwater system.  No recharge and continued pumpage lower water levels in aquifers, and ultimately impact spring flow at springs like Jacob’s Well, Park Spring, and Pleasant Valley Springs, which provide important baseflow for Cypress Creek and the Blanco River. 

Spring Flow and Streamflow

Middle Trinity springs in western Hays County were severely impacted by drought and groundwater pumpage in 2022.  USGS reports that Jacob’s Well had a daily average of 0 cubic feet per second (CFS) for 35 days in 2022. This was the fifth year Jacob’s Well stopped flowing in recent history.  Manual flow measurements confirmed 2000 was the first time Jacob’s Well stopped flowing, but continuous flow monitoring at the USGS gauge since 2005 records the durations for four additional years.

Springs such as Jacob’s Well provide important baseflow to area creeks and rivers, which in turn flow downstream and contribute recharge to downstream aquifers (such as the Edwards Aquifer).  Estimating annual discharge for Jacob’s Well shows wide variation in wet year and dry year contributions. In the graph below, the daily mean discharge in cubic feet per second was converted to acre-feet per day, then the sum for the year was calculated.  In 2022, Jacob’s Well contributed approximately 1,200 acre-feet of baseflow (fourth lowest year for annual discharge).  The highest annual discharge was over 15,800 acre-feet in 2016; and the lowest annual discharge was 908 acre-feet in 2011.

Spring flow was well below average for much of the latter half of the year.  Low spring flow created water quality concerns at Jacob’s Well and downstream at Blue Hole, which lead to Jacob’s Well Natural Area and Blue Hole Regional Park suspending swimming on XX and XX, respectively.

Groundwater Levels

Monitor wells reached lows in 2022.  

Importance of Conservation

Please continue to conserve. Coordinated water conservation is key to preserve groundwater availability, spring flow, and water supplies.  All of the Hill Country is experiencing rainfall deficits which leading to pronounced drought conditions in our area.

Most communities in the Hill Country are groundwater-dependent, so drought conditions are particularly troublesome for water supplies, recreation-based tourism, and springs and rivers.  Please follow groundwater district drought restrictions and local water provider drought water use guidance.  Limit outdoor irrigation and conserve water indoors.  Identify and fix leaks.  Conserve water to prolong water supplies until rainfall can replenish our aquifers. 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. 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
Barton Springs Edwards Aquifer CD Stage III Critical Drought (minimum of 30% Reduction) Oct 2022 Press Release, 10/20/2022
Blanco Pedernales GCD Stage 3 – 20-50% Reduction in pumping August 2022 Press Release, August 2022
Comal Trinity GCD
Cow Creek GCD Stage 3 – 30% Reduction in pumpage June 2022 Public Notice, 6/14/2022
Hays Trinity GCD 30% Curtailment for Jacob’s Well GMZ, 40% for remainder of the District July 2022 Board Order, 7/31/22
Edwards Aquifer Authority San Antonio Pool is in Stage 3 – 35% Reduction June 2022 Press Release, 6/13/22

[Updated 10/28/2022]

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
2022 Oct Recent Rains Lead to Some Flow at Jacob’s Well 10/28/22
2022 Sept What does Drought Recovery Look Like? 9/13/22
2022 June Wide-spread Drought 6/16/2022
2022 April Drought Conditions Return 4/4/2022
2022 Feb Three-month Dry Spell Ends with Icy Precipitation 5.7 cfs 16.4 cfs 2/3/2022
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.