Arroyo Colorado

About the Watershed

Where is the Arroyo Colorado?
Located in the Lower Rio Grande Valley of South Texas.
Its headwaters are southwest of the city of Mission and it drains into the Lower Laguna Madre.
It is a sub-watershed of the Nueces-Rio Grande Coastal Basin, also known as the South (Lower) Laguna Madre Watershed (Hydrologic Unit Code 12110208).
How big is the Arroyo Colorado?
It is approximately 706 square miles (1,828 square kilometers) or 451,840 acres (182,853 hectares).
It is approximately 90 miles long.
Average range of width is 40 to 200 feet.
Average depth range can be as shallow as 2 feet or as deep as 13 feet.
How do we use the Arroyo Colorado?
Primarily as a floodway and a conduit for wastewater conveyance.
For commercial barge traffic and as a recreational area for boating and fishing.
An important nursery and foraging area for numerous marine species.
Predominate land use within the watershed is agriculture (~330,000 acres) with a rapidly growing urban populations.
What feeds the Arroyo Colorado?
It has a freshwater segment (Segment 2202) and a tidally influenced marine segment (Segment 2201).
Perennial (year-round) flow is sustained mainly by flows from municipal wastewater treatment facilities.
Irrigation return flows and urban runoff supplement the flow on a seasonal basis.
What are impairments in the Arroyo Colorado?
Segments 2201 and 2202 are listed as impaired for high bacteria levels.
Segment 2201 is also listed as impaired for low dissolved oxygen.
Nutrient concentrations (nitrogen and phosphorus compounds) are high in both segments.

Additional maps, imagery and census data are also available.