Dry Fork Sink is one of Austin’s lesser known sinkholes which not many people know about. This news article will explain the environmental features of Dry Fork Sink. 
Dry Fork Sink is a karst sinkhole and recharge feature to the Barton Springs Edwards Aquifer located on a Kincheon Branch tributary. The total watershed tributary to the Dry Fork Sink is approximately 5,000 acres. (Ref: https://www.austintexas.gov/edims/document.cfm?id=117418)
A City of Austin-produced map shows that the flow path connecting to Dry Fork Sink is a flow path to Barton Springs. (Ref: https://www.austintexas.gov/edims/document.cfm?id=126059)
There are Critical Environmental Features in Dry Fork Sink as Dry Fork Sink is a Critical Environmental Feature. Dry Fork Sink has been identified by the City of Austin as a Critical Environmental Feature (CEF). [Ref: City of Austin Land Development Code, SOS ordinance section 25-8-514(B)]
This sink has been observed by the members of the Texas Speleological Survey and the Barton Springs/Edwards Conservation District staff to recharge the entire flow of Williamson Creek during some rain events. (Ref: https://www.austintexas.gov/edims/document.cfm?id=117418)
William Russell of the Texas Speleological Survey (TSS) initially reported this sinkhole to be a major recharge feature known as Dry Fork Sink in 1993. This feature was observed by the TSS and BS/EACD staff to absorb the entire flow of the tributary following some rain events. This site is adjacent to and upgradient of the community of Sunset Valley, which relies solely on water from the Edwards Aquifer for drinking water supplies. The site lies near the extension of a deep trough in the potentiometric surface and a line of faulting toward Barton Springs. (Ref: https://bseacd.org/uploads/Hauwert_COA_2004_BS-Groundwater-Tracing-Study-final_web.pdf)
A dye injected into Dry Fork Sink on June 17, 1997 was detected in Barton Springs in less than 30 hours. Tracings showed that runoff entering the Dry Fork Sink could reach Barton Springs in less than 30 hours. As part of the Watershed Protection Master Plan process, the Water Quality Protection mission identified the Dry Fork Tributary as a high priority area. (Ref: https://www.austintexas.gov/sites/default/files/files/Watershed/MasterPlan/Lundelius.pdf)
In 2003, researchers learned, for example, that dye injected into Dry Fork Sink on Kitcheon Branch -- a Williamson Creek tributary in Sunset Valley -- traveled the 41/2 miles to Barton Springs in less than 30 hours. Sunset Valley officials, mindful of the dangers facing the aquifer, have drastically changed their agenda in recent years -- from pro-growth (demonstrated by the string of big-box developments along Brodie Lane) to no-growth (evidenced by the city's ongoing legal entanglements with Lowe's). (Ref: https://www.austinchronicle.com/news/2003-05-16/159810/)
A site specific amendment to City Code Section 25-8-514 (Save our Springs Initiative) to allow construction of a pollution prevention device upstream of Dry Fork Sink in the Critical Water Quality Zone of Williamson Creek was posted in the Austin American-Stateman newspaper in 2008. (Ref: https://www.newspapers.com/newspage/357331218/)
In 2008, City Council amended a code to allow construction of a pollution prevention device in the critical water quality zone of the Williamson Creek Watershed. The pollution prevention device shall be located upstream of Dry Fork Sink in a remote area with no public access. The pollution prevention device shall be fenced. [Ref: City of Austin Land Development Code, SOS ordinance section 25-8-514(B)]
Dry Fork Sink is located behind 6804 Lost Valley, Austin, Texas, US 78745.
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