Puerto Rico TMDL and Implementation Plan Development


Developing Effective TMDL Strategies through Detailed Analysis of
Existing Data and Use of Public Domain Watershed Modeling Tools

End Client: US EPA Region 2 (in partnership with RTI International)

Paradigm led the development of 18 TMDLs for 7 large watersheds covering a diverse landscape across the island of Puerto Rico.  The TMDLs were developed for copper, lead, and mercury and required the detailed analysis of meteorological conditions as they varied significantly across the island. 

Paradigm developed a continuous simulation model using Loading Simulation Program – C++ (LPSC) to calculate existing metals loads from each watershed.  Detailed trends analyses were conducted to understand pollutant dynamics (see figure).  The analysis provided insights into the trends in observed metals concentrations in impaired waterbodies annually, seasonally, and any patterns observed based on rainfall and flow data.  Used in combination with the modeling results, Paradigm successfully worked with EPA and Puerto Rico Environmental Quality Board to develop equitable and achievable allocation scenarios and implementation plans.