Hays Trinity Groundwater Conservation District

HTGCD Mission Statement “Given the critical importance of water to life and of that part of the water cycle called groundwater to local families, agriculture, commerce, stream flows and wildlife habitat, the Hays Trinity Groundwater Conservation District works to conserve, preserve, recharge and prevent waste of groundwater within western Hays County. To help accomplish these goals the District is charged to gather information needed for sound decisions, to provide that information to citizens and local agencies, and to insure that groundwater is used efficiently and at sustainable rates.”

Texas Priority Groundwater Management Areas Hays Trinity became part of Hill County PGMA Hays Trinity became part of Hill County PGMA 2001 – HTGCD created by 77 th Legislature (S.B. 2) 2001 – HTGCD created by 77 th Legislature (S.B. 2) 2003 – HTGCD confirmed 2:1 in popular election 2003 – HTGCD confirmed 2:1 in popular election

Water Administration: Texas Water Code Chapter says: “Groundwater Conservation Districts created as provided by this chapter are the state’s preferred method of groundwater management.” Chapter says: “Groundwater Conservation Districts created as provided by this chapter are the state’s preferred method of groundwater management.”

Some Function of GCDs Provide for local control of GW resources in lieu of Rule of Capture (the right to pump all the GW you can with no consideration for the impact to other property owners or the eco-systems); Provide for local control of GW resources in lieu of Rule of Capture (the right to pump all the GW you can with no consideration for the impact to other property owners or the eco-systems); Establish GW resource management policy for jurisdiction; Establish GW resource management policy for jurisdiction; Establish GW rights and issue production permits Establish GW rights and issue production permits GCDs are accountable to electorate; GCDs are accountable to electorate;

Single Member Districts w/in HTGCD

Summary of What the District Does Not Regulate Single Household Wells- must register but not permitted or metered by the District; Single Household Wells- must register but not permitted or metered by the District; No inspection of single household wells without permission; No inspection of single household wells without permission; Wells used for conventional farming and ranching activities including such intensive operations as aquiculture, feedlots or poultry operations; Wells used for conventional farming and ranching activities including such intensive operations as aquiculture, feedlots or poultry operations; Wells used for the dewatering and monitoring of lignite production and oil & gas Wells used for the dewatering and monitoring of lignite production and oil & gas

There are over 6,650 wells in the District; District regulates less than 2%. (Exempt single family residential wells and agricultural wells may be drilled on any spacing and take water from permitted well owners and other exempt well owners)

Al Broun, P.G. District Geologist

Management Plan Goal : Maximize Development of the Trinity Aquifer and Maintain Sufficient Water in the Aquifer to Maintain 90% of Stream Leakage During A Repeat of Drought of Record.

Stratigraphy

Hays Trinity Groundwater Conservation District Trinity aquifer Water Budget Based on the TWDB Edwards-Trinity aquifer GAM (in acre-feet per year) Lower Trinity aquifer – Not Included in Model Sligo & Hosston Formations Sligo & Hosston Formations Middle Trinity aquifer Lower Glen Rose Formation Hensel Sand Cow Creek Limestone Pumping Springs & Seeps (Stream Leakage ) Springs & Seeps (Stream Leakage ) Upper Trinity aquifer Upper Glen Rose Formation Recharge (rainfall infiltration) Recharge (rainfall infiltration) Trinity aquifer Edwards aquifer Loss to Edwards Aquifer (Head Dependant Bounds) Loss to Edwards Aquifer (Head Dependant Bounds) Down-gradient Movement Out of HTGCD (Horizontal Exchange) Down-gradient Movement Out of HTGCD (Horizontal Exchange) Gains to Aquifer Storage (Storage) Gains to Aquifer Storage (Storage) Hammett Shale (aquitard)

TWDB Estimate of Useable Groundwater Total = 3,411 ac-ft per year Region K: 2,500 ac-ft per year Region L: 911 ac-ft per year Basis of Estimates:  TWDB Hill Country Trinity Aquifer GAM, 2000  TWDB State Water Plans for Region K & L [The GAM’s do not include the resources of the Lower Trinity (Sligo / Hoston)]

Geologic Map & Control Points

Lower Glen Rose, Woodcreek

Groundwater Usage HTGCD 2003 HTGCD2004 Region L 2003 Region K 2003 Region L 2004 Region K 2004 Annual Rainfall (Austin) ”52.68”25.45”25.45”52.68”52.68” Dripping Springs Water Supply Corporation Wimberley Water Supply Corporation AquaTexas/Woodcreek Woodcreek Golf Course Agricultural Usage Other Water Supply Corporations Residential, (5000 Exempt Wells) 1,8501, , ,129 Total (acre-feet) 4,2403,7852,4371,8032,1841,601 Lower Trinity Total less Lower Trinity Total less Lower Trinity3,9573,5022,3271,6302,0741,428 Available Water Available Water3,7133,7131,2132, ,500 Surplus/Deficit Surplus/Deficit(244)211(1114)870(861)1,072

Groundwater Usage Production in Acre-Feet HTGCD2003HTGCD2004HTGCD2005HTGCD2006 Annual Rainfall (Austin) ”52.68”22.33”34.70” Dripping Springs Water Supply Corporation (253)(51)(71)(193) Wimberley Water Supply Corporation (664)(564)(653)(693) AquaTexas/Woodcreek(591)(558)(666)(649) Woodcreek Golf Course (192)(72)(87)(113) Agricultural Usage (152)(152)(152)(152) Other Water Supply Cos ‘03&’04 were estimated based on connections (538)(538)(226)(376) Residential (~5,000 Exempt Wells) (1,850)(1,850) (2,032) [5,500] (2,139) [5,787] Total (acre-feet) (4,240)(3,785)(3,986)(4,315) Estimated Lower Trinity Usage Estimated Lower Trinity Usage Total less Lower Trinity Total less Lower Trinity(3,957)(3,502)(3,703)(4,030) Available Water in Upper and Middle Trinity Available Water in Upper and Middle Trinity3,7133,7133,7133,713 Surplus/Deficit in Upper and Middle Trinity Surplus/Deficit in Upper and Middle Trinity(244)21110(317)

groundwater management areas

What House Bill 1763 says Regionalizes decisions Regionalizes decisions Districts over regions Districts over regions Permitting target Permitting target

desired future conditions managed available groundwater (policy) + (science) = groundwater availability

Districts in GMAs decide Desired Future Conditions and deliver to TWDB TWDB provides estimates of Managed Available Groundwater to districts and regions Districts and regions include Managed Available Groundwater in plans

Example MAG Allocation Scenario (2006) DFC Modeling Results 3411 ac-ft Exempt Wells Residential (6650)2560 Agricultural152 MAG for Permitting699 Non-exempt Usage2125 (1425 ac-ft) Wimberley Valley Non-exempt Usage 1500 ac-ft Requested Non-exempt Irrigation Usage 600 ac-ft

Hays Trinity Groundwater Conservation District