Lake Stratification - US Army Corps of Engineers

Project Overview

Lake stratification monitoring site

The US Army Corps of Engineers (Pittsburgh District) maintains and operates reservoirs in Pennsylvania, West Virginia, and New York. The dams are constructed for selective withdrawal, with output gates at multiple levels in the water column.

Monitoring the yearly evolution of temperature stratification is a critical component in many lake management and research programs due to its pronounced effects on aquatic chemistry and biology. Lake stratification develops seasonally when surface water becomes warmer (and less dense) than deeper water. This results in temperature-dependent density differences that prevent mixing and form isolated layers of water, each with their own distinct chemistry.

Among the more common concerns is the depletion of oxygen in the deeper layers of stratified lakes during the summer months. Below the thermocline, dissolved oxygen is insufficient to support most aquatic life. The Corps of Engineers wanted a way to monitor and control the lake temperature at various stratification levels.

System Description

Data buoy deployment

The release of overly warm surface water, or oxygen-depleted bottom water, at selective withdrawal dams, could devastate downstream fish populations. At a number of reservoirs across Pennsylvania, real-time, on-line temperature stratification data is acquired using suspended from buoys. Every hour, data loggers transmit this temperature data via license-free radio telemetry to a host computer running software. iChart automatically posts the data to WQData.com on a password-protected website.

With the easy, online access provided by the NexSens system, dam operators and reservoir managers can release water from different depths selectively in order to maintain acceptable water quality conditions downstream of the reservoirs. Additionally, tracking stratification data throughout the year provides long-term data sets that aid in research efforts and the development of best management practices.