RGV North and Central Watershed Protection Plan Development

Funding provided by the Texas Commission on Environmental Quality through a Clean Water Act § 319(h) grant from the U.S. Environmental Protection Agency.

This funding is to address non-point source (urban runoff, stormwater runoff) pollution problems.

The Lower Laguna Madre (LLM) is designated as an impaired waterway for high concentrations of bacteria and low dissolved oxygen (DO).

North and Central (NC) primary waterways (Raymondville Drain, Hidalgo Willacy Main Drain, and IBWC North Floodway) in the Lower Rio Grande Valley (LRGV) have not been characterized which can potentially be the flow water carriers of these contaminants into the LLM.

• Aquatic Life
• Laguna Atascosa Wildlife Refuge: Protects nearly 100k acres of habitat.
• Recreation activities: Fishing and Swimming

For more Low- Dissolved Oxygen Information visit:  MIT (2014) Dissolved Oxygen 

• Watershed Characterization Phase I (2019-2021) UTRGV: Thesis and  Research Publication. 
• Lower Laguna Madre - Fresh Water Flows (2021-2023) - RATES

• Watershed Characterization Phase II (2022-Present) - RATES
• WPP Development Phase I (Sep 1, 2024-Present) - RATES

• Raymondville Drain
• Hidalgo Willacy Main Drain
• IBWC North Floodway

• Project Duration: 24-36 months.

• Extend Phase I Lower Rio Grande Valley-North and Central Watershed Characterization (UTRGV).
• Real-Time Hydrologic System (RTHS): Leverages three RTHS commissioned by TWDB-FWF.
• Continuous water quality measurements: Dissolved Oxygen, Water Temperature, Specific Conductivity, and Nitrate.
• Quarterly water quality and hydrodynamic measurements: Dissolved Oxygen, Water Temperature, Conductivity, pH, Nitrate/Nitrite, Total Phosphorus, Total Nitrogen (TKN), and E. coli.
• Acoustic Doppler Current Profiler (ADCP) discharge transects and flow measurements to develop discharge rating curves as a function of stage height.

• QAPP Approved Fall 2024
• Water Quality Analysis: Bacteria and nutrients concentration along with flow data will be utilized to gather actual discharge loads, the total mass of a nutrient (i.e, TP, TKN, NO ₂ -NO ₃ ) being transported in the water over a given period.
• Load Duration Curves: tool driven by discharge loads and (i.e., high, medium, low) that allows to identify potential sources of pollution, address Total Maximum Daily Loads (TMDLs), and support the development of appropriate Base Management Practices (BMPs).
• Load Characterization: Implementation of a Spatial Analysis Tool called Spatially Explicit Load Enrichment Calculation Tool (SELECT), that predicts potential E. Coli discharge loads coming from multiple sources (i.e., Wastewater Treatment Facilities, On-Site Sewage Facilities, Wildlife and Stock) per subwatershed. The results help to address in danger areas and support the development of BMPs.

a. Step 1. Build Partnerships

• i. Working at watershed level requires cooperative efforts among local stakeholders and other partners.
• ii. Partner participation ensures commitments to solutions and makes resources and skill sets available.

b. Stakeholder Identification

• i. Those responsible for implementing watershed plan.
• ii. Those affected by implementation measures.
• iii. Those who can provide information on issues and concerns in watershed.
• iv. Those with knowledge of existing programs or plans that may be applicable (e.g. soil and water conservation districts, irrigation districts, other).
• v. Those who can provide technical and financial assistance in developing and implementing plan.

c. Meeting Objective

• i. Identify stakeholder groups for each of the 3 sub-watersheds within the LRGV N&C Watersheds:
  • Raymondville Drain
  • Hidalgo-Willacy Main Drain
  • US-IBWC North and Central Watershed
• ii. Secondary objective to identify and/or nominate a chairperson for each watershed group.
  • The rational being is that individual water sheds present unique challenges and concerns that must be addressed in WPP development.

d. Step 2 - Watershed Characterization

• i. Current project (Phase II Characterization).

e.

• i Phase 1 WPP Development
  • 1. Expanding data collection to characterize causes and sources of NPS contamination.
  • 2. Data will be applied to Quantify Pollutant Loads and Sources
  • a. Applicable to BMP development

1. Stakeholder Roles
   1. Chair
   2. Members
2. Stakeholders Engagement Goals
   1. Identification of Sources of pollution
3. Stakeholder Nominations
   1. Existing Appointments
   2. Open Seats
   3. Request for Nominations

• Continuous: Real-time water quality data taken over the total length of the project (18 months).
• Instantaneous: Six quarterly sampling campaigns over the length of the project.

Instantaneous data (from sampling campaigns) is being uploaded to TCEQ via the Surface Water Quality Monitoring Information System (SWQMIS) following their criteria and methodologies.

Equipment: YSI EXO-2, Acoustic Doppler Current Profiler (ADCP), Sampling Pole.

Frequency: Quarterly based, three out of six completed.

Results: Uploaded to TCEQ through SWQMIS. Data is publicly available through TCEQ's website.

Data Collection: flow, water quality parameters, bacteria and nutrients concentration.

TCEQ's maximum allowable bacteria concentration value for Primary Contact Recreation (PCR) 1 waterways is 126 coliforms/100mL. From the 58 observations made across the three waterways, the PCR 1 criteria has been exceeded 42 times.

• Primary Contact Recreation (PCR) 1: Water recreation activities, such as wading by children, swimming, water skiing, diving, tubing, surfing, and whitewater kayaking, canoeing, and rafting, involving a significant risk of ingestion of water.
• Primary Contact Recreation (PCR) 2: Water recreation activities that involve a significant risk of ingestion of water occur, but less frequently than for PCR 1. Will be designated where recreation occurs less frequently due to physical characteristics of the water body or limited public access.
• Secondary contact recreation (SCR) 1: Water recreation activities, such as fishing, commercial and recreational boating, and limited body contact incidental to shoreline activity, not involving a significant risk of water ingestion and that commonly occur.
• Secondary contact recreation (SCR) 2: Water recreation activities, such as fishing, commercial and recreational boating, and limited body contact incidental to shoreline activity, not involving a significant risk of water ingestion but that occur less frequently than for SCR 1 due to (1) physical characteristics of the water body and/or (2) limited public access.
• Noncontact Recreation (NCR): Activities, such as ship and barge traffic, birding, and using hike and bike trails near a water body, not involving a significant risk of water ingestion, and where primary and secondary contact recreation should not occur because of unsafe conditions. The recreation use for these water bodies is protected by the same criteria and indicators assigned to contact recreation waters— E. coli, and enterococci.

• Modeling QAPP approved Fall 2024.
• Modeling efforts pending.
• Water Quality Analysis: Bacteria and nutrients concentration along with flow data will be utilized to gather actual discharge loads, the total mass of a nutrient (i.e, TP, TKN, NO ₂ -NO ₃ ) being transported in the water over a given period.
• Load Duration Curves: tool driven by discharge loads and (i.e., high, medium, low) that allows to identify potential sources of pollution, address Total Maximum Daily Loads (TMDLs), and support the development of appropriate Base Management Practices (BMPs).
• Load Characterization: Implementation of a Spatial Analysis Tool called Spatially Explicit Load Enrichment Calculation Tool (SELECT), that predicts potential E. Coli discharge loads coming from multiple sources (i.e., Wastewater Treatment Facilities, On-Site Sewage Facilities, Wildlife and Stock) per sub-watershed. The results help to address in danger areas and support the development of BMPs.

In addressing water quality concerns, relying solely on modeling output from LDCs or SELECT may provide limited insights, as they primarily focus on estimating pollutant loads and identifying critical loading periods or areas. While these methods are useful for certain types of assessments, they lack the comprehensive predictive capabilities necessary for long-term water resource management and planning.

Limitations of LDCs and SELECT

• LDCs: LDCs are static and retrospective, providing information on historical pollutant loads but not offering predictions or detailed spatial insights on how changes in land use or management practices will impact future water quality.
• SELECT: The SELECT tool does not account for the dynamic nature of watershed hydrology and lacks the capability to simulate the temporal effects of changes in land use or climate on water quality.

• Integrating other water quality models, such as the Soil and Water Assessment Tool (SWAT), alongside LDCs or SELECT, would offer a far more detailed and predictive approach to managing water quality. SWAT, for instance, simulates the complex interactions between hydrology, land use, and nutrient cycling. Additionally, it can simulate the movement of nutrients and sediments across the landscape, test BMP effectiveness, and incorporate climate projections to model future water quality.

 RTHS Datahub 

 EPA-NAD Bank 

 TWDB Fresh Water Flows