The hydrology for the model uses data collected from a hydrological monitoring index station, NP205. This station is located at the northeastern edge of the western sub-population's habitat at ~ 180 centimeters above mean sea level (MSL). From the data gathered at this gauge, daily trends in hydrology for each cell within sub-population's habitat is modeled from 1976 to 1996. This period represents the time period covered by SIMSPAR in each modeled output.
There were some periods for which no records existed for station NP205. Where there were gaps in the data for less than 10 days, the water level was estimated using linear interpolation. For a 76 day gap from April to June of 1992, values were estimated by adding a 120cm to a reading obtained from station P34. P34 is located in the southeastern corner of the sparrow's habitat at an elevation of ~ 60 cm MSL. This technique was also used to fill in a gap during the Spring of 1989. Finally, the rainfall figures for January to July 1993 were not available, so 20 year mean rainfall figures were inserted.