Barton Springs: approximately 35 cfs 10-day average
The rain over the weekend was substantial enough to create flow in area creeks where the majority of recharge to the Barton Springs Segment of the Edwards Aquifer occurs. Hopefully these rains are the precursor to the wet conditions possible with the arrival of El Niño conditions which the National Weather Service places a 58% chance of developing during winter 2014-2015 and lasting into spring 2015. Although Barton Springs experienced a sudden increase in flow due to the rain over the weekend, that increase does not indicate an increase in groundwater storage in the aquifer, rather a sudden surge of surface water travelling quickly through developed karst conduits (caves, sinkholes, etc). Lovelady monitor well hydrograph, the District's other drought trigger site, has slowed its descent into deeper stages of drought for the time being and may be indicating a subtle rise in aquifer water levels due to the rain, but whether that is the case or not remains to be seen. To see the latest official District drought status click here.
Total rainfall at the district office in November of 3.2 inches was just shy of the historic average for the month of 3.3 inches. This ahead of the 58% chance NOAA's Climate Prediction Center places on El Nino (ENSO) conditions developing this winter and extending in spring 2015. ENSO conditions generally correlate with wetter periods in central Texas. Currently, despite the average rain conditions recharge to the aquifer has been minimal and consequently water levels in the aquifer are declining after a summer of roller-coaster-like ups and downs (see drought chart here).
Stage II Alarm Drought
Lovelady monitor well: 4687.7 ft-msl
Barton Springs discharge: 35 cfs 10-day average
Over the last few months both discharge at Barton Springs and water level at Lovelady monitor well, the District's to drought trigger sites, have experienced brief two rises due to the timing of precipitation events this summer that were large enough to generate recharge to the aquifer (see figure below). Currently, with fall well underway, water level in the aquifer is on the decline, while the Climate Prediction Center, expects El Niñoconditions to develop in the next month or two, potentially bringing above average rainfall to central Texas.
Stage II Alarm Drought Lovelady Monitor well: 469.88 ft-msl Barton Springs: 35 cfs In a statement released on October 9, The Climate Prediction Center reported that El Niño conditions are likely to begin in the next 1 to 2 months. Generally speaking, El Niño conditions mean more rain for central Texas. So far this month the district rain gauge has collected just over 1 inch of precipitation of the 3.3 inch historic average. The water level in the Lovelady monitor well has experienced something of a rollercoaster of ups and downs as a result of the timing and magnitude of storms this summer see image below.
Stage II Alarm Drought
Barton Springs discharge 29 cfs 10-day average
Lovelady monitor well 469.91 ft-msl
Last week some parts of Austin received 6 inches of rain. Much of that precipitation fell directly over or slightly east of the recharge zone of the aquifer, and caused a small rise in groundwater levels and increased discharge at Barton Springs. As welcome as the rain was, it would have been much more beneficial to groundwater supply for more of it to have fallen further west in the watersheds of the creeks that flow over the recharge zone. Sustained flow in the creeks is the most important source of recharge to the Barton Springs segment of the Edwards Aquifer. Rain fall directly on the recharge zone is not as likely to generate the amounts of surface runoff and flow in the creeks that are so important to providing water to our segment of the Edwards Aquifer. The bump in water levels is unlikely to last more than a couple of weeks or lead to conditions that would call for lifting the current drought declaration. A huge benefit of the recent rains is that soils are now primed to generate surface runoff if we get even modest rains in the right places.
Click here to go to the District facebook page for more on last week's rain.
August has turned out to be a very dry month. At the time of this post, rain gauges at the District offices, Austin-Bergstrom International Airport, and Camp Mabry received little more than trace amounts of moisture during the entire month. The historic average rainfall for August is just over 2 inches. As a result of this lack of precipitation, water levels in the aquifer continue the descending trend that lead the District Board of Directors to declare Stage II Alarm drought at their last meeting on August 14.
The Board of the Barton Springs/Edwards Aquifer Conservation District unanimously declared Stage II Alarm Drought at its August 14, 2014 meeting. Both drought indicators are below their respective threshold and indicated the declaration. This triggers a mandatory monthly reduction of 20% by permittees of the District.
Both Lovelady and Barton Springs are below their respective Alarm Stage II thresholds. The Board will meet this Thursday evening and will discuss the drought status. It is likely that drought will be declared, but we'll keep everyone posted.
Water levels in the aquifer continue to recede. Since the last substantial rain event we received in July, which caused a brief rise in the hydrograph at Barton Springs, spring discharge has been steadily declining. The USGS reports the most recent instantaneous discharge value to be 45 cfs, still above the drought threshold for Barton Springs of 38 cfs. The water level in Lovelady monitor well was largely unaffected by the rain in July and has been dropping since the beginning of that month. Water level in Lovelady well is below its drought threshold. The District Board meets next week at which point they are likely to make a drought declaration if no substantial recharge occurs.
The Board decided to wait on making an Alarm Drought declaration this last Board Meeting (7/24/14) and consider action at then next Board meeting in August. Barton Springs flow continues to decline, but has not yet crossed its threshold. The Lovelady water level elevation is also continuing to decline, and is already more than 1 ft below its threshold for Alarm Stage II Drought.
Critical Stage: Barton 20 cfs or Lovelady 190.7 feet
Exceptional Stage: Barton 14 cfs or Lovelady 196.3 feet
Emergency Response Period: 10 cfs or Lovelady 200.0 feet
Either Barton Springs OR the Lovelady Well can trigger a drought declaration by the Board. However, BOTH Barton Springs AND the Lovelady Well must be above their respective drought trigger levels to exit a drought declaration.