Project Overview

Full Title
Stratification and Water Quality in the New Hope Arm of Jordan Lake, Chatham County, NC

Location
Chatham County

Cooperating Agencies
Town of Cary, NC

Project Chief
Mary Giorgino
giorgino@usgs.gov

Period of Project
2012 - 2019

Team Members
Jessica Cain
Ryan Rasmussen

Science Topic
Increased Population and Water Resources

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Stratification and Water Quality of Jordan Lake

Approach

To achieve the study objectives, the USGS will collect data:

At 4 locations in Jordan Lake
Biweekly during the months of April through October
April 2012 - October 2013 and April 2017 - October 2018

This schedule will result in 16 visits to each site per year and a total of 256 individual site visits during the study (4 sites x 16 visits/year x 4 years).

Water Column Stratification

Vertical profiles of water temperature, dissolved oxygen, pH, and specific conductance will be measured through the water column.

The vertical profile data will be used to evaluate the spatial and seasonal extent of the mixing system's effects on water-column stratification.

After the mixing system has been installed, the USGS also will attempt to quantify local circulation patterns in the lake induced by the mixing system using hydroacoustic techniques.

Water-Quality Characteristics

Secchi depth, the depth to 1 percent incident light, and turbidity will be measured near the water surface. Iron and manganese will be sampled from 2 depths that represent surface and bottom waters.

Nutrients and chlorophyll a will be analyzed from vertical-composite samples of the photic zone at all sites; nutrients also will be collected from bottom waters. At site 4, phytoplankton and taste and odor compounds (geosmin and 2-methylisoborneol) will be collected from photic-zone and bottom waters.

The USGS will document water-column and water-quality conditions in the study area before and after the vertical-mixing system is installed in a final report. Evaluation will focus on the spatial and temporal scope of mixing system's effects on lake stratification and concentrations of iron, manganese, nutrients, and taste and odor compounds.

Water-quality properties and constituents measured for the Jordan Lake study
Property or Constituent	Biweekly sampling at 4 sites April-October, 2012-2016
	Vertical profile	1 meter below surface	Photic-zone composite	1 meter above lake bed
Field Properties
Water temperature	X
Dissolved oxygen	X
Specific conductance	X
pH	X
Turbidity		X
Secchi depth		At surface
Depth to 1% incident light		At surface
Iron and Manganese
Iron, total		X
Iron, dissolved		X
Manganese, total		X
Manganese, dissolved		X
Nutrients
Nitrogen, ammonia			X
Nitrogen, total ammonia + organic			X
Nitrogen, nitrite + nitrate			X
Phosphorus, orthophosphate			X
Phosphorus, total			X
Phytoplankton and Taste and Odor Compounds
Chlorophyll a			X
Phytoplankton identification and enumeration			X(1)	X(1)
Geosmin			X(1)	X(1)
2-Methylisoborneol (MIB)			X(1)	X(1)

(1) Collected at site #0209799150

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