September Aquifer Update

Drought Stage: Critical Stage III
Lovelady: 191.8 ft depth to water
Barton Springs: 18.7 cfs 10-day average

Repeat of the Drought of Record?

Excerpt from the TWDB Newsletter September 2011...

Ocean Temperatures and Predicting Drought in Texas
The current drought in Texas is capturing national and international attention. While it's not unusual for Texas to experience dry spells, the current dry spell is notable for its fierce intensity and state-wide impact resulting in record-breaking low rainfalls and record-breaking high temperatures across the state. The state climatologist has already declared the current dry spell the worst one-year drought in Texas' history. Given how drought prone Texas is, that's saying something.

There's an old saw among ranchers that one more day of drought means one day closer to rain. But the question remains: When will this drought break? Ultimately, no one knows. However, scientists often look to sea surface temperatures for clues on long-term weather trends.

Oceans impact the atmosphere and thus the weather (short-term variations) and the climate (long-term variations). A dramatic example is a hurricane where warm sea surface temperatures feed large swirling storms. When a hurricane moves from ocean to land thereby breaking the ocean-atmosphere connection, it rapidly weakens. More subtle changes in ocean temperatures also affect the weather and climate.

A well-known example of how subtle changes in ocean temperatures impact the weather in Texas is the El Niño Southern Oscillation (known by the cool kids as "ENSO"). This oscillation is represented by sea surface temperatures in the eastern equatorial region of the Pacific Ocean. Sometimes the temperatures are warmer than usual (El Niño conditions), sometimes they are cooler than usual (La Niña conditions), and sometimes they are in-between (neutral conditions). Any particular ENSO phase tends to persist for 6 to 18 months. Scientists have noticed that El Niño conditions tend to result in wetter conditions in Texas during the winter months and a general suppression of tropical storm activity and that La Niña conditions tend to result in dryer conditions in Texas with a greater number of hurricanes with greater intensity in the Atlantic. The current drought started with the onset of La Niña conditions. We are currently in a neutral phase with a 50 percent chance for a return of La Niña conditions this fall and winter. A return of La Niña means the probable persistence of the current drought.

There are other less talked about sea surface temperature oscillations that appear to relate to the climate of Texas. One is the Pacific Decadal Oscillation and the other is the Atlantic Multidecadal Oscillation. The Pacific Decadal Oscillation (PDO) is represented by a seesaw of sea surface temperatures between the central Pacific and the Pacific coast of North America. It typically lasts for 20 to 30 years. Currently the PDO is in a "cool" phase with cooler sea surface temperatures along the Pacific Coast. Similar to ENSO, the PDO's cool phase is associated with below average rainfall and higher temperatures for the southern United States and northern Mexico. "Warm" PDO events are associated with the opposite: lower temperatures and higher rainfall.

The Atlantic Multidecadal Oscillation (AMO) is represented by sea surface temperatures in the northern Atlantic Ocean. AMO is associated with the frequency and severity of drought in North America and the frequency of severe hurricanes in the Atlantic. Two of the most severe droughts in North American recorded history, the Dust Bowl and the drought of the 1950s, occurred when a warm AMO that lasted from 1925 to 1965 lined up with La Niña and PDO events. A cool AMO persisted from 1965 up until the mid-1990s when warm conditions returned.

There are other oscillations besides the PDO, ENSO, and AMO that are known to affect climate in Texas. Some of these include the North Atlantic Oscillation (NAO), the Madden Julian Oscillation, the Indian Ocean Dipole, and the Southern Annular Mode. The North Atlantic Oscillation (NAO) has a major influence on winter climate in the northern hemisphere. How the NAO may interact with ENSO, PDO, and AMO in influencing the climate over Texas is still unclear. Factors such as changes in the "preferred" locations of atmospheric high pressure systems and storm tracks also influence climate over Texas. Some of these factors are directly influenced by the oscillations. Some are the result of a dryer land surface leading to warmer temperatures leading to less rainfall that further dries out the land surface and increases warming....and so on in a feedback loop. Some of these other oscillations are known to act in concert with ENSO and may have some (as yet undefined) role to play in the occurrence and severity of drought in Texas.

While the phase of any of these oscillations, individually or collectively, doesn't guarantee drought or non-drought conditions, certain phases appear to increase the chances that we will see certain climatic conditions. During the drought of the 1950s, a warm AMO, a cold PDO, and a La Nina lined up for the hotter and drier conditions that defined our drought of record. Interestingly (and perhaps alarmingly), with warmer sea surface temperatures in the north Atlantic, cooler temperatures along the Pacific Coast, and recent and projected La Nina conditions, all three seem to be lining up again...

NOAA's State of the Climate: August 2011

Click here to see the complete details and overview of August 2011 from NOAA. Some of the climatic "highlights" noted in this overview include:

"....Texas is experiencing a drought of greater intensity, but not yet duration, than those of the 1930s and 1950s.

An analysis of Texas statewide tree-ring records dating back to 1550 indicates that the summer 2011 drought in Texas is matched by only one summer (1789) in the 429-year tree-ring record, indicating that the summer 2011 drought appears to be unusual even in the context of the multi-century tree-ring record."

Aquifer Update: Critical Stage III Drought

Drought Status: Critical Stage III
Barton Springs: ~20 cfs (10-day average)
Lovelady Water Level: 191.4 ft

Click here to read a recent article in the NY Times titled: "Sacrifices and Restrictions as Central Texas Town Copes With Drought"

Press Release: District Declares Stage III Critical Drought

For Immediate Release:  Thursday, September 8, 2011

For more information, contact: Robin Gary, Public Information and Education Coordinator, (512) 282-8441 or rhgary@bseacd.org

Stage III Critical Groundwater Drought Declared

(Austin)  The Board of Directors of the Barton Springs/Edwards Aquifer Conservation District declared Stage III Critical Drought at its Board meeting this evening, effective immediately.  With hot temperatures, no rain, and no replenishing creek flow, water levels in the area aquifers continue to decline.  Both of the District’s drought triggers have now crossed their respective Stage III Critical Drought thresholds.  The Lovelady Monitor Well depth-to-water fell below 190.7 feet and, based on manual measurements, the Barton Springs 10-day average discharge is less than 20 cubic feet per second.

Under Stage III restrictions, permittees are required to reduce monthly pumping by at least 30% for historical permits and over 75% for conditional permits.  Water utilities supplied by groundwater in the District will be implementing additional restrictions on their end-user customers to reach the drought curtailments. These restrictions effectively protect groundwater supplies by slowing water level declines.

This year has become the driest one-year period on record.  The NOAA Climate Prediction Center shows drier than normal conditions for the area extending through this winter..  In 2009 during the last Stage III Critical Drought, the District received many ‘dry well’ reports. Water conservation can help prolong water supplies and delay well issues.

“Groundwater is a shared resource.  Regardless of where you get your water—whether you use your own well, a neighborhood water system, or a city system with multiple water sources—reducing water use is essential.  We’ve got to be water wise as a community.  We are all in this together,” commented Mary Stone, District Board President.

The 60,000+ existing groundwater users in the District are now required to cut back their monthly water use another 10% and heed more stringent restrictions.  Their water suppliers (and/or the District) will inform end-users as to what obligations they must follow under Stage III Critical Drought.  Generally, all outdoor irrigation of lawns and landscaping is now prohibited. Groundwater uses are restricted to water for essential indoor demands needed to preserve health and safety with a very minor allocation provided for some non-essential outdoor water uses such as maintaining small lawn areas for fire protection and foundation damage prevention. The District’s staff is committed to ensuring that such restrictions are as equitable as possible and will be taking steps during drought to promote that:

·         New water withdrawal permits in the Edwards Aquifer will not be authorized during this drought; 

·         The restrictions included in the User Drought Contingency Plans that are part of every groundwater use permit will be aggressively enforced; and

·         Rules that prohibit wasteful groundwater use will be enforced.

The District asks all of its constituents to continue their water conservation measures and be even better stewards of an increasingly scarce resource.  Water conservation information and updated aquifer conditions are available on the District’s website at www.bseacd.org. With continued lack of significant rainfall and high rates of pumping, water levels could drop to the extent that some wells could go dry and flow from Barton Springs could eventually decrease to the point where ecological, recreational, and aesthetic uses of Barton Springs would be damaged.  The aquifer can no longer afford anything other than minimal use, and that may be the situation for many more months.

La Nina conditions return

The Climate Prediction Center has issued a La Nina Advisory and state that La Nina conditions have returned and are expected to gradually strengthen and continue into the Northern Hemisphere winter 2011-2012.

La Nina conditions generally result in drier-than-normal weather patterns. However, tropical systems could still provide some much-needed rainfall this Fall.

June-August period in Texas was hottest on record in U.S.

Click here for an article from the Star-Telegram.

Stage III Critical Drought imminent

Barton Springs discharge and the depth to water in the Lovelady monitor well are likely to cross their respective thresholds in the next week. It is possible the Board would make a Stage III Critical Drought declaration at its next meeting on Thursday 9/8/11. Stage III drought will require that permitees reduce monthly pumping by about 30% of their normal monthly pumping.