Wastewater Discharge Impacts On Estuary Nutrient Dynamics

from Two Downstream Watersheds:Río Piedras and Río Grande de Manatí

Co-Principal InvestigatorsCristina I. Maldonado Morales -UPRRP

Limarie J. Reyes Torres -UPRRPKhrisia A. Torres Camacho-UPRRP

CIAM 6117

Research Problem

● Wastewater discharges is one of the most severe environmental problems affecting water bodies (including estuaries) in Puerto Rico.

● Contribute significant amounts of nutrients (nitrogen (N) and phosphorus (P)) causing water quality degradation:○ eutrophication○ accelerated plant growth○ algae blooms○ low dissolved oxygen (hypoxia)○ death of aquatic animals

Research Problem● Wastewater treatment plants (WWTPs) and failing septic systems are

sources of N and P into aquatic systems.

● In Puerto Rico:○ Only 65% of the population is connected to sewer service from the

Puerto Rico Aqueduct and Sewer Authority (PRASA).

○ The exact amount of existing septic systems is unknown.

○ Accurate quantity measures of wastewater entering our estuaries is unknown.

○ Little is known about the damage and water quality deterioration occurring in estuaries due to wastewater discharges.

Goals and Objectives● Main Goal: assess and compare the effects of anthropogenic nutrient inputs (N and P) from

wastewater discharges of two different watersheds into two estuarine ecosystems.

○ Objective 1: Determine if external sources of nutrients derived from wastewater are present in both watersheds.■ Hypothesis: External sources will be present in both watersheds.

○ Objective 2: Determine if the N and P loads will be higher in one watershed when comparing one another.■ Hypothesis: N and P loads will be higher in the Río Piedras watershed.

○ Objective 3: Determine if N and P gradients exist and evaluate their patterns.■ Hypothesis: N and P gradients exist and will decrease from upstream to

downstream.

Goals and Objectives● Gather sound scientific information that aids in the development and

implementation of policies to:○ Improve wastewater disposal management strategies.

○ Protect and restore water quality in watersheds and estuaries.

● This research project aligns with the goals and strategies of the UPR Sea Grant 2014-2017 Strategic Plan as research focused on the area of Healthy Ecosystems and Habitats - Estuaries○ Coastal water quality degradation

○ Influence of anthropogenic activities on coastal ecosystems

Methods:Sampling SitesRio Piedras Watershed and Río Grande de Manatí Watershed

www.recursosaguapuertorico.com

Rio Piedras Watershed

Google Earth

DRNA Watershed data

Drainage Basin Area: San Juan/49km2 (DNER)

Climate: Moist Subtropical ((DNER)

Average Rainfall: 77”(rainy season); 53”(dry season) (DNER)

Geology: mostly volcanic (DNER)

Population: 259,595 (Census)

Land Use: 77% Urban, 21% Forest/Pastures,

0% Agriculture (USFS)

Wastewater Discharges: PRASA: One WWTP, effluent to Atlantic Ocean (avg. of 56.6 mgd)

Non-PRASA: USGS, EQB data show sewage discharges from

septic tanks (DNER)

Data sources:DNER-Department of Natural and Environmental Resources of Puerto Rico,2004Census-“Junta de Planificación” 2010 CensusUSFS-United States Forest Service, 2011

DRNA Watershed data

Río Grande de Manatí Watershed

Drainage Basin Area: Orocovis, Barranquitas, Ciales,

Manatí and Barceloneta/608 km2(DNER)

Climate: Moist Subtropical (DNER)

Average Rainfall: 77”(rainy season); 53”(dryseason) (DNER)

Geology: Karst, volcanic (DNER)

Population: 127,000 (DNER)

Land Use: 60% Forest and Pasture,

5% Urban,6% Agriculture(UPRRP-GSP)

Wastewater Discharges: PRASA: Three WWTPs

Watershed no longer meets the applicable water quality standards for Puerto Rico (EQB)

Google Earth

DRNA Watershed data

Data sources:DNER-Department of Natural and Environmental Resources of Puerto Rico,2004EQB- Enviromental Qulality Board, 2010UPRRP-GSP- N. Valentín,UPRRP Graduate School of planning,2010)

Sampling Sites: Río Piedras Watershed

Modified from Department of Natural and Environmental Resources of Puerto Rico Watershed Data

Sampling Sites: Río Grande de Manatí Watershed

Modified from Department of Natural and Environmental Resources of Puerto Rico Watershed Data

Methods: Phosphorus and Nitrogen determination

Hach, Total Phosphorus Test Kit Hach, Total Nitrogen Test KitLaMotte 2020we KitPortable Turbidity Meter

http://www.hach.com/phosver-3-phosphate-reagent-powder-pillows-25-ml-pk-100/product?id=7640196804 http://www.lamotte.com/en/water-wastewater/instrumentation/1970.html

http://www.hach.com/drb200-digital-reactor-block-15-x-16-mm-vial-wells-115-vac/product?id=7640453262#http://www.hach.com/nitrogen-total-tntplus-lr/product?id=7640209878http://www.hach.com/total-nitrogen-reagent-set-lr-tnt/product?id=7640209858

● Total Nitrogen Persulfate Digestion Method

● Measures all forms of nitrogen present in the

water samples

● Acid Persulfate Digestion Method ● Measures all forms of phosphorus

present in the water samples

● Measures how much the material suspended in water decreases the passage of light through the water.

Methods: Data Collection and Analysis

Nutrient Loads and Discharge data

● WWTP discharge values will be taken from the National Pollutant Discharge Elimination System permits

● Watershed discharge values will be taken from the USGS streamflow data sampling points

Analysis● Monthly and annual

○ average discharge values○ nutrient concentrations ○ nutrient loads

● T test to determine significant differences ○ nutrient and river discharges ○ dry and rainy seasons

Activities/Timetables2016 J F M A M J J A S O N D

Public Outreach x

Water sampling x x x x x x x x x x x x

Data Analysis x x

Web page creation x x

2017 J F M A M J J A S O N D

Public Outreach x

Water sampling x x x x x x x x x x x x

Data Analysis x x x x

Final Report / Paper publication

x x x

1. Raised awareness by public outreach. 2. Results will have short, medium and long term impacts because the data collected can be

used to: ○ Evaluate how nutrient flows vary in the watershed depending on the decrease or

increase of wastewater discharges. ○ Compare past and future studies in the two watersheds with our data.

3. Data collected can be used by government agencies, the academia and other interested parties.

4. By providing a better understanding of the watersheds’ nutrient dynamics, this study will aid

in the development of appropriate technologies and management strategies that will protect and restore coastal ecosystems and resources

Potential Benefits

Budget Summary

Total Request $ 28,676.64

Major Expenses $ 16,276.64 (Permanent equipments and wages)

Match Funding $ 30,000

Thank you for your attention

Photos by USGS, Caribbean Water Science Center Hydrologic Technicians

Río Piedras Río Grande de Manatí