The Raymondville Drain collects stormwater runoff and return flows from subwatershed with predominant agriculture activity. The North Floodway pilot channel constantly drains WWTP effluent and during large storm events, collect excess runoff from urbanized areas of Hidalgo County and agriculture land in Cameron and Willacy County. The Hidalgo Main Drain carries urban stormwater runoff from central and northern Hidalgo County, and agricultural runoff from northeast Hidalgo County and Willacy County.

Background Information

The Raymondville Drain and the Hidalgo Main flow into the Lower Laguna Madre Bay assessment unit (AU) 2491_01 which is impaired for low dissolved oxygen (DO). The North Floodway flows into the Lower Laguna Madre AU 2491_02 which is impaired for low DO and bacteria.

The project area is comprised of subwatersheds associated with the Raymondville Drain, the Hidalgo Floodway, and the IBWC pilot channel (IBWC North Floodway). These major waterways contribute freshwater and stormwater to the Laguna Madre. This project will begin the assessment of these subwatersheds. It is anticipated that these three distinct subwatersheds will need to be assessed, quantified, and identified as separate major watersheds in the Lower Rio Grande Valley.

Project Overview

In an effort to address the concerns and impairments of the Lower Laguna Madre(2491) assessment units 01 and 02, the watersheds of the Raymondville Drain, the Hidalgo Floodway, and the IBWC Floodway must be characterized to identify potential causes and sources. This project will identify existing data and identify data gaps for characterization as well as identify a path forward by selecting an analytical method for estimating pollutant loads. This project will also engage, educate, and solicit input from stakeholders on the goals, objectives, and indicators for addressing the impairments and concerns. Ultimately, it is the goal of this project to partially accomplish Element A and initiate Element E of EPA’s nine elements for watershed-based plans found in the Handbook for Developing Watershed Plans to Restore and Protect our Waters.
This project will start the watershed characterization by acquiring existing data from various sources, identifying potential causes of water quality impairments and issues, identifying potential sources of pollution and relative contribution, and completing an inventory of data. Through the IBWC, Hidalgo County Drainage District No. 1 and the Willacy County Drainage District, UTRGV will gathered all the flow and waters quality data that these agencies have collected over the years. This data will be analyzed, categorized and evaluated (based on reliability and accuracy) to identify information that can be used to assess current conditions. A conceptual model will be developed to show the linkage between the water quality problems and sources of impairments. This analysis, to the extent possible, will include a spatial and temporal exploration of water quality problems and sources of pollution in the watershed. Identification and analysis of existing data will assist in determining data gaps and what data needs to be collected in the future. Additionally, the existing data and new data will drive the selection of the analytical method that will be used for estimating pollutant loads.

The Lower Rio Grande Valley North and Central Watershed Characterization-Phase 1 was completed August 31, 2022. A contract to conduct Phase II Characterization of the North and Central Watershed was executed September 1, 2022.  Phase II characterization will involve a combination of: quarterly sampling events to measure water quality and stream discharge; and 2) continuous monitoring to measure hydrologic and water quality parameters.

Workgroups Meeting Schedule

Steering Committee and Workgroup Meetings

Outreach Activities 

Resources

Public Participation Plan for the North and Central Lower Rio Grande Valley Watershed Protection Plan

Quality Assurance Project Plan (QAPP)

Existing Data Report

Interim Data Analysis Report 02-21

Funding
Funding provided by the Texas Commission on Environmental Quality as part of a Clean Water Act Section 319(h) Grant.

Contact Info