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. Page Quicklinks:

October 2020 Hydro Report

 

Groundwater Drought Declarations

Agency Drought Stage Date Declared Details
Hays Trinity GCD Jacob’s Well GMZ – 20% Curtailment
Remaining GCD – 20% Curtailment		 Sept. 2020 Board Order, 10/1/2020
Barton Springs Edwards Aquifer CD Stage II Alarm Drought (20% Curtailment or more) Oct. 2020 Press Release, 10/9/2020
Edwards Aquifer Authority No Drought (however the J-17 monitor well has fallen below the 660′ elevation drought threshold, so Board action is imminent)

We’ve seen a series of rain events over the past few weeks, and rivers and springflow have responded!  The Edwards Aquifer Authority weather station on the Blanco River upstream of Wimberley measured over 8 inches of rain in September alone. The rainfall initially generated considerable runoff–seen in the graph above as a high peak flow in both the Blanco River and Cypress Creek.  Soils absorbed a lot of the rainfall and shallow soil moisture levels have increased.

Smaller creeks and tributaries responded during the rain event but stopped flowing shortly after the rainfall. Springflow at Middle Trinity springs (such as Jacob’s Well, Pleasant Valley Springs, and Park Springs) increased after the rains, but have begun declining since no additional recharge is making its way into the groundwater system.  These springs continue to provide baseflow in the Blanco River and Cypress Creek. Pleasant Valley and Park Springs’ flow is estimated by the USGS gage near Fisher Store Rd. Jacob’s Well flow is measured at the USGS gage at the Natural Area.

Water levels in monitor wells have slowed their decline and have plateaued due to input from recharge.  This trend is observed in HTGCD monitor well data (from west to east) in the Burnett Ranch and the Mt. Baldy wells. Review of the BSEACD monitor wells shows the Edwards Aquifer is behaving similarly. Water levels in the Hoskins and Lovelady wells have benefitted from recent rains and declines have slowed and plateaued.  If additional rains add more recharge to the groundwater systems, those water levels could increase.

The Hays Trinity Groundwater Conservation District (HTGCD) declared 30% Drought Curtailment for the Jacob’s Well Groundwater Management Zone and 20% Drought Curtailment for the remainder of the GCD effective for September (HTGCD Press Release).  Jacob’s Well flow dropped below its drought threshold of 5 cfs for the 10-day average.  The coordinated reduction in groundwater use will help prolong groundwater availability and extend supplies for all users.

To preserve our water resources, conservation is key–especially during these dry times. Outdoor landscape and lawn irrigation can account for up to 60% of household water use. During these dry summer months when springflow and groundwater levels are low, please limit outdoor water use and if you do choose to water outdoors, do it in the early morning or late evening to limit evaporation. Native and drought-tolerant landscaping is paying off now–those plants are accustomed to hot, dry Texas summers. Keep an eye out for leaks, and use water wisely.

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 springflow 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
    • Springflow is a strong indicator of groundwater levels in the Jacob’s Well Groundwater Management Zone (JW GMZ), because low springflow directly correlates to low well water levels.
    • The 10-day average springflow 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.  Stream flow 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:

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