2021 March Hydro Report

On March 23, the Wimberley area received almost 1 inch of rainfall.  This will help add moisture to very dry soils, but it will do little to generate recharge to the rivers and aquifers.  Flow at Jacob’s Well is very low–consistently below 2 cubic feet per second, and water levels in HTGCD monitor wells are below levels measured during 2011 drought.  The water level at the HTGCD Mt. Baldy Well reached it’s lowest point on record this month.

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.

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 on March 23.  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.

To allow repairs at a dam on Cypress Creek downstream of Jacob’s Well, the dam gates have been removed, which has lowered the water level in the pool at Jacob’s Well.  While the gates are out, spring flow from the Well itself is visible.  As repairs are finalized and checked, the flow calculations at the gauge will likely overestimate discharge.  For a discussion of how flow is measured at Jacob’s Well, visit the Jacob’s Well Flow Monitoring page.

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 No Drought Mar. 2021 Press Release, 3/5/2021


For updates, useful links, and archived Hydro Reports, visit the WVWA Water Monitoring page.

[Updated 3/23/2021]