In Texas, Seaway passes through the following 16 Texas counties: Grayson, Collin, Rockwall, Kaufman, Henderson, Navarro, Freestone, Leon, Madison, Grimes, Waller, Harris, Fort Bend, Brazoria, with terminal segments to Chambers and Jefferson counties.
Seven of these counties (highlighted above) are within the purview of the Region C Regional Water Planning Group. Region C is responsible for water planning in the DFW area.
At least three aquifers are crossed by the pipeline to its refinery destination: the Trinity, Carrizo Wilcox and the Gulf Coast.
The Trinity is a major aquifer for DFW water supplies. 
Water is not the sole risk for counties. Counties are having to resort to lawsuits to recover expenses for repairing roads that were damaged as the result of pipeline construction. 
1. ^Texas Water Development Board http://www.twdb.state.tx.us/
2. ^Kaufman County reaches settlement with pipeline company for damage to county roads http://inforney.com/local-news/item/5212-kaufman-county-reaches-settlement-with-pipeline-company-for-damage-to-county-roads