4.3.4.1 Livestock
Manure applied due to grazing, feeding operations, and winter feeding areas were major bacterial sources in this study. Livestock population at the county and watershed level was estimated using agricultural census/GIS layers data (USDA, 2006). The county animal census population was equally distributed per total land-area basis to determine the fraction of total livestock in the study watershed. The USDA data were compared with Kansas Department of Agriculture farm facts data from the Kansas Department of Agriculture (KDA, 2004a). The AUs in feedlots within the watershed were estimated using active feedlot data (both federally permitted feedlots >1000 AUs and state registered feedlots > 300 AUs) from the Kansas Department of Health and Environment (KDHE) (Jepson, 2005). Permitted and registered livestock were subtracted from the total number of animals in the watershed to estimate the net grazed livestock population. Animal stocking rates in the
pastureland was also validated using county-wide livestock population data (KDA, 2004b). Animals in the pasturelands could be brought from feedlots, barnyards and leasing agreements for grazing during the warm season (generally from April to September). However, the stocking rate of the animals in the pastureland was assumed to be maintained.
The populations of all animals in the watersheds were estimated based on 1000-kg AUs. The Rock Creek watershed was populated with 558 beef animal units (AU) in the pastureland (based on stocking rate), 104 beef AUs in the feedlots, and 223 beef AUs in the winter feeding areas (40% of 558), which was modeled in this study to represent the current scenario of the watershed. Similarly, Deer Creek watershed was estimated with 311 beef AUs in the pastureland (based on stocking rate), 73 beef AUs in the feedlots, and 124 of the beef AUs in the winter feeding areas, which was modeled
in this study to represent the current scenario of the watershed. About 8.5% of the livestock source loads were considered direct point loads in this study whereas 17% was considered for the sub- watershed where permitted feedlots were located. Manure production (26.4 kg day -1 AU-1) and fecal coliform bacteria concentration (13x1010 cfu day-1 AU-1) for each beef animal were estimated based standard production rates (ASAE, 2000). The bacteria concentration was converted into model-input units of colonies forming units (cfu) per gram of dry-weight manure using standard mean manure moisture content (86% moisture; ASAE, 2000).
4.3.4.2 Human
Digital orthophoto quarter quadrangles (State of Kansas, 2002) of the watershed was
digitized depending on the physical context, roads, and type of houses to represent each septic system in the watershed. Each rural house was assumed to have one septic system, resulting in a total of 107 septic systems for the Rock Creek watershed and 229 septic systems for the Deer Creek watershed. About 20% of the estimated septic systems were assumed failing in the watershed for modeling in this study. The number of failing septic systems may vary with in the watershed depending on the type of design, construction, and operation and maintenance (KDHE, 2000).
Each septic system was assumed to be used by three persons in the household that can contribute about 0.32 m3 of sewage effluent per day (USEPA, 2001). The failing septic systems in the watershed were modeled using 90% land application method and 10% direct point load. Parajuli, et al. 2006 found higher model sensitivity when applying septic effluent as direct point load method than land application method. The fecal bacteria concentration in failing septic system was taken as 6.3x106 cfu 100 mL-1 (Overcash and Davidson, 1980).
4.3.4.3 Wildlife
No comprehensive wildlife inventory was available for the Rock Creek watershed. The wildlife population density was estimated based on the information received from the Kansas Department of Wildlife and Parks (KDWP). The 2002 summer road-kill indices survey data from KDWP furbearer biologist (Peek, 2005) for Kansas were used to estimate small-mammal populations in the watershed. The information include various wild-animal species: raccoon, opossum, striped skunk, coyote, badger, bobcat, red fox, gray fox, swift fox, beaver, mink, muskrat, river otter, spotted skunk, weasel, armadillo, woodchuck and percupine. The population of raccoon, opossum, striped skunk, and coyote constituted about 81% of the total small mammals in Kansas. Population of the predominate large mammal (white-tailed deer) in the watershed was estimated based on expert
opinion from the KDWP big-game coordinator (Lloyd, 2006). Similar data were collected for the predominate indigenous avian species (turkey) from the KDWP small-game coordinator (Pitman, 2006); migratory birds (duck geese, sandhill crane) from the KDWP waterfowl research biologist (Kraft, 2006)
In order to estimate the animal units of each wildlife species in the watershed, the population data were first distributed over the potential habitat for each species. Small mammals and turkey population data were counted from a road survey. Most of the small mammals were counted dead at the road shoulder. The sight distances of 5 m for small mammals and 50 m for turkey from each side of the road were assumed, and the population density of each species was estimated as number of animal per unit area using total length of the road driven during survey. For deer, the number of deer harvested in northeastern Kansas was estimated and equally distributed in the total land area of northeastern Kansas to get the deer density. Migratory birds (duck, geese, and sandhill crane) are available in the watershed for about seven months of the year (Jan-March and Sept-Dec). The Kansas population of these wildlife species was equally distributed over the water surface area and wetland area to get their population density. The population density in the watershed was estimated based on the available water surface area.
The Rock Creek watershed was populated with 60 turkey AUs, 24 deer AUs, 7 small mammal AUs, and 36 migratory bird AUs which was modeled in this study to represent the current scenario of the watershed. Similarly, Deer Creek watershed was populated with 41 turkey AUs, 16 deer AUs, 5 small mammal AUs, and 27 migratory bird AUs which was modeled in this study to represent the current scenario of the watershed. About 10% of the wildlife source loads were
considered direct point loads in this study. Animal weights were estimated based on the information received from “mammals of Kansas” (Timm et al., 2007) and personal communication (Pitman, 2006). It was estimated that about 0.80 kg ha-1 day-1 dry weight of total wildlife manure is applied in the different landuses of the watershed depending on the wildlife species, specific seasons, habitat and feeding areas (pastureland, woodland, cropland) which is a source of fecal coliform bacteria simulated in this study.