AWRI Information Services Center

Fremont Lake Watershed Modeling

 
Three tools were used as part of this project to further identify areas of concern in the Fremont Lake Watershed. Click the modeling name below to learn more about the results each of the models predicted for Fremont Lake. For a complete version of the modeling results read Chapter 4 of the Baseline Study of Fremont Lake and its Connecting Waterways report. 

PLOAD

L-THIA NPS

ISAT


PLOAD

The U.S. EPA's Pollutant Loading Model (PLOAD) calculates pollutant loadings for sub-basins using the different land use and cover periods (1978, 1998, and 2005), hydrologic soil groups, and precipitation. The PLOAD model results demonstrate across the board increases from 1978 to 2005 in total nitrogen, total phosphorus, and total suspended solids for the Fremont Lake Watershed. This increase is a result of the change in land use and cover (increase in urban/built up lands) and could also be due to changes in the amount of precipitation. 

 

Fremont Lake 2005 PLOAD
 Total Nitrogen
Fremont Lake 2005 PLOAD
Total Phosphorus
Fremont Lake 2005 PLOAD
Total Suspended Solids

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LTHIA-NPS

The U.S. EPA's Long-Term Hydrologic Impact Assessment and Nonpoint Source Pollutant (LTHIA-NPS) model was used to evaluate stormwater runoff status in the Fremont Lake Watershed. The model runs for the LTHIA-NPS program were intended to be compared to the PLOAD outputs for the Fremont Lake Watershed. The LTHIA-NPS model shows that during a rain event, the highest volume of runoff comes from Daisy Creek, Fremont Drain, and Brooks Creek sub-basins.

Fremont Lake 2005 LTHIA-NPS
 Runoff Volume for Average Annual Rainfall
Fremont Lake 2005 LTHIA-NPS
 Runoff Depths for Average Annual Rainfall

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ISAT
 
The National Oceanic and Atmospheric Administration Coastal Services Center developed the Impervious Surface Analysis Tool (ISAT) as a modeling program designed to determine the total percentage of impervious surface area within a watershed area. Impervious surfaces are mainly constructed surfaces—rooftops, sidewalks, roads, and parking lots—covered by impenetrable materials such as asphalt and concrete. Stormwater washes over these impervious surfaces and carries pollutants directly to the nearest body of water. The watershed sub-basins within the Fremont Lake Watershed with the highest percentage of impervious surface area determined by the ISAT model were Daisy Creek, Fremont Drain, and Brooks Creek.
 

Fremont Lake 2005 ISAT
 Impervious Surface Analysis

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Page last modified March 30, 2010