The Lower Rio Grande Valley (LRGV) of South Texas contains an extensive stormwater conveyance canal system supported by culverts and crossings. This project examined representative canal segments in this system to determine the effects of stormwater conveyance structures and crossings as well as surrounding land use on water quality and the ability of the canal system to meet Texas freshwater surface water standards. Data collected for 18 physiochemical and nutrient parameters was used to generate summary statistics and perform analyses of variance and correlation analyses. The results of the analyses suggested that conveyance structures and crossings and land use significantly affected 12-13 water quality parameters. Box culverts in the canal system are more likely to affect water quality than bridge crossings or culverts placed above and below the water surface. Agricultural and residential land, roads, and trees and bushes planted on the canal boundaries effected water quality similarly, whereas the maintained, vegetated edges of canals had the greatest influences on water quality. Overall, water quality in the LRGV canal system meets federal and state standards and aquatic life criteria. The findings of our water quality survey provide significant information that could assist with municipal, county, and regional environmental compliance management.