The Great Lakes Water Balance
Data Availability and Annotated Bibliography
By Brian P. Neff and Jason R. Killian

Introduction | Hydrological Information | Forecasts and Summary

Introduction

Great Lakes hydrologic data are collected and compiled by many government agencies in both the US and in Canada. Based on this hydrologic information, water balances are calculated for the Great Lakes system. In reality, the Great Lakes water balance is actually the combination of six distinct water balances; one for each Great Lake and Lake St. Clair. The term "water balance" is defined herein as an accounting of the inflow to, outflow from, and storage in, a hydrologic unit, such as the Great Lakes (Langbein and Iseri 1983). The mathematical expression of a water balance is: water in equals water out, plus or minus change in storage. 

Many different processes contribute to these three components. Inflows to the Great Lakes are the sum of five specific elements; direct precipitation, runoff, ground water seepage, flow through the connecting channels and through the diversion of water into the Great Lakes basin. Water leaves the system four ways; through the connecting channels and the St. Lawrence River, evaporation, consumptive use and by way of diversions of water out of the watershed. Change in storage is a function of change in lake level, but can be affected by thermal expansion or contraction of the water bodies. 

The purpose of this work is to describe the source and location of all major datasets that can be used to quantify the three components of the Great Lakes water balance. Additionally, this report contains annotated bibliographies of selected interpretive studies of Great Lakes hydrology. It should be noted that the scope of this work does not attempt to provide an exhaustive inventory of all existing datasets. This discussion is intended to be limited to wide-ranging, long-term hydrologic records

References

• Bibliographies of selected references

• Full reference list

• Sources of Hydrological data and information

This report is prepared by USGS in cooperation with the Great Lakes Commission.

The Great Lakes Commission is a  multi-agency, multi-disciplinary, multi-faceted team approach to addressing the science and policy of a Great Lakes water management regime will produce such application-oriented products as a water use web site, updated annual water use inventories, ecological evaluations of the system, and an integrated binational role for future Great Lakes-St. Lawrence endeavors.