Creeping into Drought

Drought Status: Stage II Alarm Drought
Lovelady Monitor Well: 462.67 ft-msl
Barton Springs: 28 cfs (approximate 10-day average)

The recent rains were a welcome change from the generally dry conditions we have been experiencing. Due to the prolonged dry conditions that have been prevailing however, much of the rain we received went to replenishing soil moisture and only a small fraction to recharging the aquifer. The stretch of Onion Creek that contributes most to recharge of the aquifer experienced minimal flow during the recent rains.

Flow at Barton Springs is more susceptible to spikes than is Lovelady Monitor Well. The most recent District staff stream flow measurement at Barton Springs yielded a flow of 32 cfs, with a 10-day estimated average flow of 28 cfs. The rains slowed the fall of the water level in Lovelady monitor well from dropping below the Stage III Critical drought threshold of 462.7 ft-msl when it was expected to.

The District's board convened yesterday evening to assess the drought conditions. It decided, to give the General Manager the authority to declare Stage III drought once district staff confirms that water level in the Lovelady monitor well has not risen above the 462.7 ft-msl drought trigger threshold for two consecutive days. It is likely that this criteria will be met Tuesday or Wednesday of next week (April 16th or 17th respectively).

Thanks to the recent moisture, the aquifer is primed for recharge if we receive more precipitation in the coming weeks. However, as you may know, the drought prognosis for central Texas is bleak. The US Seasonal Drought Outlook by the National Weather Service predicts drought in in our area to "persist or intensify," while the US drought monitor rates central Texas' drought as "severe to extreme."

Drought Trigger at Lovelady Reached

Drought Status: Stage II Alarm Drought
Lovelady Monitor Well: 462.67 ft-msl
Barton Springs: 20 cfs (approx. 10-day average)

Yesterday, 3/27/12, District staff made a manual measurement of the water level in the Lovelady monitor well and found that it was at 462.67 ft-msl, below the drought trigger for Stage III Critical Drought of 462.7 ft-msl. Making reliable discharge measurements at Barton Springs has been difficult due to the construction occurring at the pool. However, only one of the drought trigger sites that the District uses (Barton Springs and Lovelady monitor well) needs to drop below its respective threshold in order for the District's Board to make a drought declaration. The board will likely declare Stage III Critical Drought at their next meeting on Thursday, April 11, 2013.

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Critical Stage III Drought Approaching

Drought Status: Stage II Alarm Drought

Barton Springs: 21 cfs (10-day average)

Lovelady Well: 463.2 ft-msl

Unless we get substantial rainfall soon, the Board will likely need to consider declaration of Critical Stage III Drought in its April Board meeting.

Steady Decrease in Lovelady

Drought Status: Stage II Alarm Drought

Barton Springs: 22.2 cfs*

Lovelady Well: 463.8 ft-msl

*Construction at Barton Springs pool is causing unreliable discharge measurements

The date in early March on which the Stage III Critical Drought threshold was expected to be crossed has been moved to later in March after a better fit was made between the Lovelady monitor well hydrograph and the recession curve during the 2011 drought (see graph below). Construction continues at the Barton Springs pool making accurate flow measurements difficult to obtain. Due to the uncertainty of flow at Barton Springs, the District is relying more heavily on the water level in the Lovelady monitor well to determine the stage of drought. The current water level in the well is just over foot above the elevation marking the onset of a Stage III Critical Drought. Water level in the well is steadily dropping and will likely cross into Stage III drought before the end of the month. 

Click on image to enlarge.

Hydrograph of Lovelady monitor well.

Closer to Drought Declaration

On Thursday, February 21st district staff measured flow at Barton Springs to be 20.13 cfs, corresponding to a 10 day average of 21.8 cfs. At that time the USGS website was reporting 26 cfs as it's "most recent instantaneous value." As of February 26th the USGS website is still reporting 26 cfs. Construction be done at the Barton Springs pool is causing flow conditions downstream to be highly variable and making it difficult to get consistent measurements. The case may be that flow at Barton Springs is somewhere between the two values of 20.13 and 26 cfs reported by the District and the USGS respectively.

However, based on the rate of decline of the water level in the Lovelady monitor well (the district's other drought trigger) it appears that the Stage III Critical Drought threshold of 462.7 ft-msl will be passed on approximately March 10, 2013. Drought stage can be declared by the board if thresholds at either of the drought trigger sites have been passed. Stage III Critical Drought corresponds with a 10-day flow average at Barton Springs between 20 and 14 cfs.

Hydrograph of Lovelady monitor well. (click to enlarge)

Critical Stage III Drought likely by early March

Drought Status: Alarm Stage II
Barton Springs: 21.8 cfs (10-day average)
Lovelady well: 464.5 ft-msl

Today district staff measured discharge to be 20.13 cfs at Barton Springs. Based on the rating curve for Barton Springs, it is likely that the 10-day flow average will drop below the 20 cfs threshold for declaring a Stage III Critical  drought before the end of February or in the first few days of March. The subsequent drought declaration could potentially be made made by the district's board at their meeting on March 7.

Drought Conditions Continue

Drought Status: Alarm Stage II
Barton Springs: 29 cfs (10-day average)
Lovelady: 466.6 ft-msl

Drought conditions continue in early 2013 and, unfortunately, the forecast is for hotter and drier conditions than normal. If these dry conditions continue, data from Barton Springs indicates we could enter into Stage III Critical Drought as early as mid- to late-February. Data from our other drought trigger, the Lovelady Well, suggests we'll enter into Stage III by early March. It only takes one of our triggers to cross its respective drought threshold for the Board to make a drought declaration.

Data for Barton Springs may be a little bit elevated above the actual discharge values as suggested by some recent manual measurements and the level in the Lovelady well. We will continue to collect more information and possibly revise our estimates. Below are charts estimating the entry into Stage III by using recession data from the 2011 drought.

Drought Prediction Chart

Need More Rain to Improve Drought Status

Drought Status: Stage II Alarm
Barton Springs: 28.6 cfs (10 average)

Lovelady well: 468 ft-msl

The precipitation received this week is a welcome respite from the overall dry conditions that have prevailed in the area this winter. The District's rain gauge reads about 2.5 inches received over the past 48 hours (Jan. 8 and 9). However, the rains have not been substantial enough to generate any considerable amount of runoff in the creeks over the contributing or recharge zones of the Edwards Aquifer. Most of the water went to replenishing soil moisture.  Despite not generating runoff, the recent rains have primed soil moisture conditions for generating recharge to the aquifer in the event of more precipitation in the next few weeks.

According to the National Weather Service the outlook for more precipitation in central Texas in January and February is not promising, having predicted drought conditions to "persist or intensify". If dry conditions persist, it is likely that the aquifer will enter Critical Stage III drought in March. 

2012 warmest and second most extreme year on record for contiguous U.S.

http://www.ncdc.noaa.gov/sotc/

Above is a link to the 2012 State of the Climate by the National Climate Data Center.

2012 Year in Review

Barton Springs: 29 cfs

Lovelady: 468.2 ft-msl

Over the past year the aquifer has experienced multiple drought stages. The aquifer started 2012 in Critical Stage III drought, brought about by the most severe single-year drought in Texas history. Above average rainfall in the winter and early spring months of 2011-2012 generated sufficient soil moisture, runoff, and sustained creek flow to recharge the aquifer enough for the District’s board to downgrade the Critical Stage III drought to Alarm Stage II in February and “No Drought” conditions in March. Above average rainfall conditions persisted until about mid-April allowing Barton Springs to reach a peak discharge above 100 cfs. After the above-average wet conditions at the start of the year, precipitation in May was not substantial enough to maintain recharge conditions at former rates. Flow in creeks began to subside, diminishing the amount of recharge entering the aquifer. The summer months in 2012 were very dry causing creeks to eventually stop flowing over the recharge zone and aquifer levels to continue to decrease. By late August, flow in Barton Springs had reached 69.3 cfs. Precipitation in September was scarce and a steady decrease of aquifer levels continued. Meager rainfall in October was not sufficient enough to overcome the soil moisture deficit incurred during the summer and therefore unable to generate runoff or creek flow to recharge the aquifer. Dry conditions persisted in November; the Board declared Alarm Stage II Drought on November 15 after both official drought indicators at Barton Springs and Lovelady monitor well passed their drought thresholds of 38 cfs and 478.4 ft-msl respectively. That alarm stage remains in effect as of January 4, 2013. The total rainfall recorded at the district for 2012 of about 35 inches was above the yearly average for the area (33.38 inches). Despite the above-average rainfall, it is likely the exceptional recharge deficit incurred during the 2011 drought has prevented the aquifer from maintaining non-drought levels.

The U.S. Seasonal Drought Outlook by the National Weather Service indicates that drought conditions are expected to “persist or intensify” for central Texas through January and February of 2013. According to previous recession curves for Lovelady monitor well, if precipitation conditions remain scarce the drought threshold for a Critical Stage III drought will likely be passed in early March 2013.