Surface-Water, Water-Quality, and Ground-Water Assessment of the Municipio of Ponce, Puerto Rico, 2002-2004

By Jesús Rodríguez-Martínez, Luis Santiago-Rivera, José M. Rodríguez, and Fernando Gómez-Gómez


In cooperation with the


Scientific Investigations Report 2005-5243


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The U.S. Geological Survey in cooperation with the Municipio Autónomo de Ponce conducted a comprehensive surface- and ground-water resource assessment, and bacteriological analysis of rivers and streams within the territorial limits of this municipio. The main objective of this study was to acquire a database that will help the municipal government of Ponce ensure an adequate supply of drinking water at present and meet future demand. The study consisted of the evaluations of the surface-water resources, streams sanitary conditions, and ground-water resources.

The surface-water assessment portion of this study focused on analysis of low-flow characteristics in local streams and rivers, because the supply of safe drinking water was a critical issue during recent dry periods. Low-flow characteristics were evaluated for three index stations based on graphical curve-fitting techniques and log-Pearson Type III frequency curves. Estimates of low-flow characteristics for 27 partial record stations were generated using graphical-correlation techniques. Flow duration characteristics for the continuous- and partial-record stations were estimated using the relation curves developed for the low-flow study. Stream low-flow statistics document the general hydrology under specific-land use, water-use, and climatic conditions.

A survey of streams and rivers utilized 27 sampling stations to evaluate the sanitary conditions of about 130 stream miles. River and stream samples for fecal coliform and Escherichia coli analyses were collected on two occasions at base-flow conditions to identify potential sources of contamination. Bacteriological analyses indicate that a significant portion of the rivers and streams in Ponce comply with the fecal coliform sanitary quality goal established for inland surface waters in July 1990 by the Puerto Rico Environmental Quality Board. Long-term monitoring of bacterial concentration of surface waters at three sampling stations in the municipio of Ponce have been in compliance with the water-quality goal for fecal coliform concentration established in July 1990. Long-term monitoring of bacterial concentration of surface water at another sampling station has mostly exceeded the fecal coliform sanitary quality goal established in July 1990. Approximately 40 percent of the rivers and streams reaches, particularly in the headwaters of the main rivers, comply with the water-quality goals of the Puerto Rico Environmental Board of fecal coliform for inland waters, as amended in 2003.

Potential sources of fecal contamination in urbanized areas include illegal discharge of waste water to storm-water drains, overflows from sewer mains into the storm-sewer drains, ruptured sewer mains, and leakage from sewer mains into the local aquifer. In rural areas, the potential sources of fecal contamination include gray-water discharge from residences and commercial establishments along stream channels, septic tank leakage or overflows, fecal contamination directly into streams by unfenced livestock, and runoff from restrained animals and poultry pens near stream courses.

Geologic, topographic, soil, hydrogeologic, and streamflow data were compiled in a database and used to divide the municipio of Ponce into six hydrogeologic terranes. This integrated database then was used to evaluate the ground-water potential of each hydrogeologic terrane. Lineament-trace analysis was used to help assess the ground-water development potential in the hydrogeologic terrains containing igneous rocks. This study indicates that further ground-water development in the municipio of Ponce is hindered by the potential of water-quality deterioration caused by the occurrence of brackish and saline ground water, particularly in the coastal plain.






Description of the Study Area

Physical Features

General Geology

Previous Studies

Chapter A: Surface-Water Resources Assessment of the Municipio of Ponce, Puerto Rico, 2002-2004

Purpose and Scope


Results and Interpretation

Low-Flow Characteristics at Continuous-Record Gaging Stations

Low-Flow Characteristics at Partial-Record Stations

Flow-Duration Characteristics

Drainage-Basin Area/Discharge Relation

Map Features

Reservoir Sites

Flood-Prone Areas

Salt Water Wedge at Streams

Public-Supply Water Filtration Plants and Waste-Water Treatment Facilities

Chapter B: Sanitary Quality of Surface Water During Base-Flow Conditions in the Municipio of Ponce,
Puerto Rico, 2002
Purpose and Scope

Field-Data Collection

Analytical Techniques

Stream Ranking Rationale

Results and Interpretation

Río Inabón Basin

Río Bucaná Basin

Río Matilde Basin

Chapter C: Hydrogeologic Terranes and Ground-Water Resources in the Municipio of Ponce,
Puerto Rico, 2002-2004
Purpose and Scope
Recent Impacts on the Ground-Water Flow Pattern in the Municipio of Ponce

Hydrogeologic Terranes

Base-Flow Measurements

Ground-Water Quality

Oxygen-18 and Deuterium Composition

Streamflow Seepage Surveys

Mechanisms of Salinization and Delineation of Saline Ground-Water Zones

Lineament-Trace Analysis

Delineation of Potentiometric Surface

Estimates of Ground-Water Withdrawals

Results and Interpretation

Hydrogeologic Terranes

Ponce Hydrogeologic Terrane 1 (PonHT1)

Ponce Hydrogeologic Terrane 2 (PonHT2)

Ponce Hydrogeologic Terrane 3 (PonHT3)

Ponce Hydrogeologic Terrane 4 (PonHT4)

Ponce Hydrogeologic Terrane 5 (PonHT5)

Ponce Hydrogeologic Terrane 6 (PonHT6)

Ground-Water Quality

Oxygen-18 and Deuterium Composition

Mechanisms of Salt Water Encroachment and Delineation of Saline Ground-Water Zones

Lineament-Trace Analysis

Potentiometric Surface

Ground-Water Withdrawals

Summary and Conclusions1

Cited References




1.Streamflow and bacteriological data collection sites, selected hydrologic features, and sanitary classification of streams with drainage to or within the municipio of Ponce, Puerto Rico

2.Hydrogeologic terranes, selected subbasins, potentiometric surface of the coastal aquifer, lineament traces, and selected well locations within the municipio of Ponce, Puerto Rico


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The citation for this report, in USGS format, is as follows:


Rodríguez-Martínez, Jesús, Santiago-Rivera, Luis, Rodríguez, J.M., and Gómez-Gómez, Fernando, 2005, Surface-water, water-quality, and ground-water assessment of the municipio of Ponce, Puerto Rico, 2002-2004: U.S. Geological Survey Scientific Investigations Report 2005-5243, 96 p., 2 pls.


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