Lake Mapping Program

Introduction

The lake mapping program was developed as a cooperative initiative between the Nebraska Game and Parks Commission and the U.S. Bureau of Reclamation (BOR) to provide detailed survey information on Nebraska's lakes and reservoirs. Each year a list of proposed lakes and reservoirs is submitted by biologists across the state and reviewed by a committee to determine the lakes of highest priority. A number of factors are taken into consideration including Aquatic Habitat Projects, lake conditions, fish communities, and angler use. The overall goal of the program is to provide fisheries managers with detailed information to be used in management and monitoring of Nebraska's lakes. Detailed bathymetric lake maps are also produced and made available to the public on the NGPC web site.

Primary uses of lake mapping data

Fisheries Managers:

Anglers:

Hunters:

Other State and Federal Agencies:

Making the lake maps

An outline of the lake is created from an aerial photo and a series of survey transects are drawn perpendicular to the shoreline. This information is loaded onto a laptop computer and will serve as a guide to ensure a sufficient amount of data is collected during the survey.

Data is collected in the field using a specially designed survey boat equipped with a GPS receiver, laptop computer, and depth sounder.

Using computer software the GPS and depth sounder are linked together on the laptop resulting in 3-dimensional points that contain a latitude, longitude, and depth. The position of the boat is displayed on a map containing the lake outline and transects allowing the driver to travel along each transect collecting points.

In addition to the boat survey, a GPS base station is set up at a known latitude, longitude, and elevation in close proximity to the lake. This base station will communicate with roving receivers carried in backpacks which are used to get an elevation of the water allowing the points collected on the boat to be converted from depths to real elevations. The roving receivers can also be used to map habitat structures and exposed shorelines during low water conditions.

Data is collected in the field using a specially designed survey boat equipped with a GPS receiver, laptop computer, and depth sounder.

Once all of the data has been collected for a lake, each transect must be edited to remove any bad points that where collected. These bad points are usually caused by some type of interference such as aquatic vegetation or fish.

The next step is to import the points into a computer program, where they can be transformed into a detailed contour map of the lake. From this map general information about the lake can be derived including the volume, area, and depth.

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