There is an obvious mistake in my previous post . The date should read" By 1890" instead of 1990.
The Arroyo Colorado flows from the area southwest of Harlingen, Texas below La Feria and Mercedes, west thru Harlingen and over to the Laguna Madre in the East and into the Gulf of Mexico. It could be this is the arroyo your husband remembers being mentioned.
Please let me known if you would like to exchange more information.