Rain not enough to cause flow in Onion Creek; Recharge minimal

Stage III Critical Drought
Barton Springs: 28.3 cfs 10-day average
Lovelady monitor well: 461.3 ft-msl

The rains that came through the area last weekend (May 25-26) helped diminish the rainfall deficit that has grown over the course of the drought declared in November 2012. As of May 30, 2013  the total rainfall deficit since November 2012, compared to the historical average of 19.4 inches over that time period, is -6.2 inches according to district rain gauge totals.

As welcome as any rain during periods of drought, the recent rains were not large enough to generate substantial runoff, and consequently flow in the creeks responsible for the majority of the recharge that enters the Barton Springs segment of the Edwards Aquifer was also minimal. Despite not having generated substantial recharge to the aquifer, the rains have replenished soil moisture such that another storm in the coming days would be more likely to create the much needed recharge.

Barton Springs flow experienced a spike in discharge reaching a 35 cfs day-average on May 26, but is once again on the decline with a 10-day average of 28.3 cfs as of today and the USGS reporting 28 cfs as the most recent instantaneous discharge measurement. Lovelady monitor well showed a small leveling out of its water level due to the rain but is once again on the decline.

The U.S. Drought Outlook by the National Weather Service shows ongoing drought with "some improvement" and the U.S. Drought monitor rates the drought in Travis and Hays counties as moderate to severe.

Aquifer Update

Drought Status: Stage III Critical Drought
Barton Springs: 23 cfs 10-day average
Lovelady Monitor Well: 461.5 ft-msl

Since the declaration of Stage II Alarm drought on November 15, 2012 water levels in the aquifer have been in steady decline. Sporadic minor rain events delayed entry into Stage III Critical drought, but did not provide enough moisture to reverse the trend in water levels. The storms that have brought much of the precipitation to the area have not been close enough together in time to overcome soil moisture deficits.  Dry soils have prevented much of the water from the recent storms from reaching creeks and consequently the aquifer. As a matter of course, the District declared Stage III Critical drought on April 17, 2013 when the water level in the Lovelady monitor well, one of the District’s drought triggers, dropped below its Stage III drought threshold of 462.7 ft-msl (see figure 1). Discharge at Barton Springs, the other drought trigger site, is declining but has not dropped below its threshold of 20 cfs due to its nature of responding quickly to minor rains over the recharge zone of the aquifer. Even though the rains that have kept flow at Barton Springs above its Stage III Critical drought threshold are a welcome reprieve from dry conditions, they have not been large enough to generate substantial runoff in the creeks where most of the recharge to the aquifer occurs. The total rainfall so far for the drought that started in November is 8.6 inches, compared to the historical average of 18.2 inches over the same time period, leaving a rainfall deficit of -9.6 inches. Onion Creek, where many of the most significant recharge features for the aquifer are found, has not had significant flow since July 2012. Currently the US Drought Monitor rates the drought in Hays and Travis counties as severe to extreme. The National Weather Service shows central Texas as having “ongoing drought” but with “some improvement” possible in the future.

Stage III Critical Drought Declared

Drought Status: Stage III Critical Drought

Lovelady Monitor Well: 462.52 ft-msl

Barton Springs: 26 cfs  (approximate 10-day average)

Stage III Critical drought was declared today by the District's GM. At last weeks meeting, the Board of Directors gave the GM authority to declare Stage III drought after the water level in the Lovelady monitor well did not rise above 462.7 ft-msl in a two day period. Manual measurements by staff and logged continuous water level data confirm that in fact, water level has not risen beyond that level during the last 48 hours. 

The District uses two drought indicators, Barton Springs and Lovelady monitor well.  Barton Springs is much more susceptible to spikes in discharge induced by rainfall causing instantaneous and 10-day average flow there after the recent rains to be non-representative of the status of the aquifer. However only one of the drought triggers needs to pass a drought threshold for a change in drought stage to be declared.

Stage III drought entails a 30% curtailment in the amount of water permitees are allowed to pump.

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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