NewsDrop-October-2024

EAA CRITICAL PERIOD MANAGEMENT PLAN

HOW THE EAA MANAGES CRITICAL STAGE REDUCTIONS

CALL FOR CONSERVATION MEASURES

By: EAA Water Resources Department

CRITICAL AQUIFER LEVELS

THE SAN ANTONIO POOL San Antonio Pool pumping permit reductions apply to Atascosa, Bexar, Caldwell, Comal, Guadalupe, Hays, and Medina counties.

THE UVALDE POOL The Uvalde pool pumping permit reductions only apply to Uvalde County.

The intent of the EAA Critical Period Management (CPM) Plan is to sustain aquifer and springflow levels during times of drought. CPM applies to most well owners who have a permit to withdraw water from the Edwards Aquifer by temporarily reducing their authorized withdrawal amount.

Why do we need to know Springflow? The Comal and San Marcos Springs provide habitats for threatened and endangered species that are protected under the Edwards Aquifer Habitat Conservation Plan (EAHCP), which can serve as indicators species for the health of the aquifer.

CPM reductions differ for each aquifer “pool” and are based on 10-day averages of certain aquifer level and springflow readings which are indicators of the current condition of the aquifer.

Please note: Residents and businesses who receive their water from a public water system are encouraged to check with their water provider to determine to how stage reductions could impact them.

The EAA uses springflow to balance the water needs for more than 2.5 million people that rely on the aquifer.

For more information or questions, please call the EAA Critical Period Team at (866) 931-3239 or email us at info@edwardsaquifer.org.

Figure 2. EAA Critical Period Management (CPM) Plan for the Uvalde Pool.

Figure 1. EAA Critical Period Management (CPM) Plan for the San Antonio Pool.

*Stage 5 Comal Springs Flow - to enter this stage based on the springflow, the reading must be less than 45 cfs on a ten-day rolling average, or less than 40 cfs based on a 3-day rolling average. To leave this stage, the 10-day rolling average must be 45 cfs or greater.

CPM is triggered and declared for the San Anto nio Pool (all counties within EAA jurisdiction except Uvalde) when the 10-day average level at the J-17 Index Well, in Bexar County, drops below 660 feet above mean sea level (msl) or the 10-day average springflow at Comal or San Marcos Springs falls below 225 cubic feet per second (cfs) or 96 cfs, respectively. As a result, permit holders must reduce groundwater with drawals by 20% of their authorized annual with drawal amounts based on the number of days CPM is in effect.

in 10-day averages. These stages are illus trated in figure 1 and figure 2 and show the different degrees of critical period manage ment we implement based on a combination of conditions. For the San Antonio Pool, the area indexes are the J-17 Index Well, Comal Springs, and San Marcos Springs. However, for the Uvalde Pool the area index is only the J-27 index well. Therefore, required reductions increase as aqui fer levels or springflows decrease, depending on which pool is in CPM. For example, Stage 1 of

In addition, all municipal, industrial and irriga tion well owners are required to submit monthly withdrawal reports to the EAA for tracking of their pumping. These reports are reconciled at the end of the year to ensure permit holder compliance with the CPM reductions. What are the stages of permit reductions and when are they declared? The CPM Plan is divided into five stages of escalating, reduced-pumping requirements, each triggered by declining aquifer levels or springflow discharge rates as calculated

Who does this apply to? CPM stage reductions apply to all Edwards Aquifer well owners and groundwater permit holders authorized to pump more than three acre-feet annually. This applies to industrial, irrigation, and municipal users, including water utilities authorized to pump Edwards groundwa ter for delivery to their respective customers.

The EAA Critical Period Management (CPM) Plan helps sustain aquifer and springflow levels during times of drought by temporarily reducing the authorized withdrawal amounts of Edwards groundwater permit holders. By curbing pump ing from the aquifer during periods of little or no rain, this program is designed to slow the rate of decline in aquifer levels and spring dis charges until such time that it does rain, and the aquifer can recharge itself.

9

8