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Modeling Lake Data

Numerous lakes are monitored each year through the MPCA’s lake monitoring program, Clean Water Partnership (CWP) Program and related assessment efforts by county government, watershed districts, lake associations and others. An important part of these assessments includes analyzing and reporting on the data that has been collected. The following provides access to two commonly used lake eutrophication models. Models provide a quantitative framework for interpreting monitoring data and a basis for predicting changes in water quality based on various characteristics of the lake and its watershed.

The Minnesota Lake Eutrophication Analysis Procedure (MINLEAP) is a computer program (model) designed to predict eutrophication indices in Minnesota lakes based upon lake surface area, mean depth, watershed area and ecoregion in which the lake is located. This model was developed by Bruce Wilson (MPCA) and Dr. William Walker, Jr. in 1988, and was originally written in BASIC but was later converted to a Windows format in 1997 by Wade Gillingham (MPCA). The current version of MINLEAP (1.xx) is a 16-bit program developed on Windows 95 and Beta tested on Windows 3.1. This version should be compatible with both operating systems and newer versions of Windows as well.

• MINLEAP Overview

The program formulates water and phosphorus balances and uses a network of empirical (regression equations) models to predict lake phosphorus, chlorophyll-a, and transparency values. The program is intended primarily as a screening tool for estimating lake conditions with minimal input data and for identifying "problem" lakes. Included in the program output are: (1) statistical comparisons of observed and predicted phosphorus, chlorophyll-a, and transparency values; (2) uncertainty estimates; and (3) estimates of chlorophyll-a interval frequencies (nuisance frequencies) for observed and predicted conditions. The model should be used to approximate lake water quality expectations, acknowledging that individual lakes may deviate greatly for regionally defined patterns.

MINLEAP is routinely used in the MPCA’s lake water quality studies and is recommended as a starting point for modeling efforts on these or similar projects. In more complex projects that may include observed data from several adjoining lake basins, chains of lakes, and/or where tributary loading data are available, a more complex model such as the US Army Corps of Engineers (USACE) BATHTUB model is recommended. BATHTUB is an empirical model that was developed based on data from USACE reservoirs. As such, it is a good tool for modeling reservoirs, chains of lakes, lakes with multiple inlets or situations where more detailed nutrient and water budgets are required. BATHTUB is used routinely in CWP studies and will also be used as a part of assessments for developing nutrient-based Total Maximum Daily Load studies. A related data-reduction tool entitled FLUX is routinely used in CWP for reducing tributary flow and concentration data and making unbiased estimates of pollutant loading. Both tools are available on the USACE Web site.

MINLEAP Installation

MINLEAP is distributed as a self-extracting executable file named:

• SETUP.EXE

1. To install:
   Create a new directory from File Manager or Explorer, or from the DOS command line by typing MD\ [directory name]
2. Copy the file to the new directory.
3. Execute the program by double clicking SETUP.EXE from Explorer or File Manager, or type SETUP.EXE from the DOS command line.

The file should self-extract into three files:

MNLPXXXX.EXE - the program file; XXXX stands for the current version number.
MINHELP.HLP - the program help file
EAGLE.MNL - a test case
UPGRADES.TXT - a list of upgrades made to the original version

Execution:
To run the program, simply double click MNLPXXXX.EXE from Explorer or File Manager, or create a new program icon: Windows 3.1
1) create a new group by clicking [File] [New], or open an existing group.
2) open the file manager
3) position the windows so both the program group and file manager can be seen.
4) drag the MNLPXXXX.EXE file to the new program group.

Windows 95
1) open Microsoft Explorer
2) drag MNLPXXXX.EXE to the wallpaper

Disclaimer:
MINLEAP is intended for research and not for business application.

MINLEAP is provided "AS IS" without warranty of any kind, either express or implied, including fitness for a particular purpose. In no event shall the authors of this software be liable for any damages whatsoever including direct, indirect, incidental, consequential,
loss of business profits or special damages.

For further information

• MINLEAP development refer to: Wilson, C. B. and W.W. Walker Jr. 1989. Development of lake assessment methods based upon the aquatic ecoregion concept. Lake and Reservoir Management. 5(2): 11-22. Or contact Bruce Wilson at 651-757-2828
• On Windows-based operation of MINLEAP or program bugs contact Wade Gillingham at 507-537-7163. Both may also be reached at the Minnesota Pollution Control Agency 1-800-657-3864.