Oregon Lake Inventory

Introduction

The Oregon Lake Inventory is a pilot project intended to update the Atlas of Oregon lakes. A goal is to eventually update the Atlas with new information and bathymetric maps using the web as the publishing medium. Currently there are ten lakes completed for the project. The lake list is at right and a geographic representation of locations is presented below.

Oregon Coast Lakes and Ecoregions

Oregon Ecoregions Map

Methods

Introduction

The Oregon Lake Inventory project is an effort to update the Atlas of Oregon Lakes, a seminal work that studied 100 lakes throughout Oregon. The Atlas was published in 1983 and since that time technology has improved to allow better data collection. The water quality and overall condition of lakes in Oregon has changed since 1983 as well. This project has two goals: The first is to update lake bathymetry and the second, to collect current water quality information.

The methods used to collect data for this project are outlined here.

Bathymetry

Historic bathymetric data collection was performed without the assistance of GPS equipment available today. Collecting bathymetric data for this project involved using a digital echosounder and very accurate GPS equipment. The result is a bathymetric map of very high accuracy.

The equipment used was a Biosonics DE series digital echosounder. The echosounder worked in tandem with a Corvallis Microtechnology GPS receiver coupled with real time position correction supplied by an antenna to receive the Coast Guard correction signal.

Detailed instructions on how the bathymetry data was collected can be found on the bathymetry project page.

GIS

GIS technology was used extensively during this project. Route planning prior to visiting the lake enabled complete coverage once in the field. GIS was used to mark equidistant transects that were followed when collecting data. After data were collected ArcView GIS was used to map the data points on the lake outline and create the shaded bathymetric maps.

ArcView was also used to map watersheds at each lake. Watershed area was delineated and the area inside was calculated. Vegetation types within the watershed were calculated by percent of watershed.

Water Quality

Water quality information was collected using a Hydrolab DataSonde 4 sampler to collect:

* Temperature (c)
* Dissolved Oxygen (% saturation)
* Dissolved Oxygen (mg/l)
* Conductivity (µS/cm)
* pH
* Oxidation Reduction Potential (mV)
* Turbidity (NTU's)
* Light (Photosynthetically Active Radiation µE/s/m)

Water samples were collected in bottles and analyzed in the laboratory for:

* Soluble Reactive Phosphorus (mg/m3)
* Total Phosphorus (mg/m3)
* Nitrate (mg/m3)
* Nitrous (mg/m3)
* Total Nitrogen (mg/l)
* Chlorophyll a (mg/m3)

Glossaries

Several online glossaries are avialable to answer questions about terms or methods related to water quality monitoring. Select any of the three links below to access the information.

http://waterontheweb.org/resources/glossary.html
Extensive information about aquatic studies

http://ga.water.usgs.gov/edu/dictionary.html
USGS Water Science for Schools glossary of terms

http://www.epa.gov/volunteer/lake/index.html
Volunteer lake monitoring protocol