**Barton Springs Turf**

This scenario is intended to represent turf areas (golf courses, parks,
sod farms, and recreational fields) in the Barton Springs Segment (BSS)
of the Edwards Aquifer. Because golf courses are expected to be the most
likely turf areas where pesticides may be applied, much of this scenario
has been parameterized to be reflective of golf course turf. NASS data
for 1997 and 2002 (USDA 1997, 2002) contained no record of sod harvest
in either Hays or Travis counties. Since there are several golf courses
located within the BSS (COA 2003), this scenario was parameterized to
represent turf on golf courses and may be generally representative of
other potential turf areas.

Crop parameters are based primarily on bermudagrass (*Cynodon* spp.)
since it is a primary turf grass for golf courses and athletic fields.
Within the vicinity of the BSS, bermudagrass is a common turf grass for
golf courses, specifically common and improved bermudagrass (personal
communication with Nick Smithamn). Bermudagrass is also used for lawns,
parks, playgrounds, and cemeteries. In the U.S., the distribution of
bermudagrass extends from across the Southern states, including: Texas,
California, New Mexico, Arizona, Oklahoma, Arkansas, Mississippi,
Alabama, Florida, Georgia, South Carolina, North Carolina, Virginia.
There are several different varieties of bermudagrass that are used for
golf course turf and sports fields, including: U-3, Tiflawn, Tifgreen,
Tifway, Santa Ana, Ormond, Tifdwarf, and Pee Dee (Duble 2004).
Bermudagrass grows on a wide variety of soils, from heavy clays to deep
sands; tolerating acidic, alkaline and saline conditions. Bermudagrass
does best on well-drained sites. Bermuda grass can survive low fertility
conditions but requires high nitrogen concentrations for production of
good quality turf (Duble 2004).

Soils were selected based primarily on the extent within golf courses in
BSS, with secondary emphasis placed on the extent within other turf
areas (parks and cemeteries). Based on a geospatial analysis of soils
(USDA 2006) and land use data (COA 2003), Brackett soils were chosen to
represent turf in the BSS (Table 5). It should be noted that the land
use classifications were not solely turf and may have included some
forested areas within golf courses and parks. Therefore, after soil
extents were computed, soils were cross-checked with aerial photography
to ensure that the soil chosen was representative of turf areas where
pesticides would realistically be applied (non-forested areas). The soil
series were also cross-checked with NRCS crop suitability ratings (USDA
2006) to ensure the series supported improved bermudagrass.

The Brackett series was chosen to represent turf areas in the BSS (Table
5) because it is a benchmark soil, is highly representative of golf
course areas in the BSS, and it represents the 90^th^ percentile of
vulnerability in drainage, erodibility, and slope. Brackett soils are in
Hydrologic Group C soils and are found in both the contributing and
recharge zones of the Edwards Aquifer. Bracket soils are the most common
soil found in golf course areas (USDA 2006; COA 2003) and the second
most common within the entire turf land cover class (golf courses,
cemeteries, parks, and greenways). Since this scenario is intended to
represent golf course type areas, Tarrant soils (also widespread) were
considered inappropriate for pesticide modeling since Tarrant soils
occur in predominantly forested areas of parks and golf courses where
pesticides would not likely be applied (based on analysis of soils and
aerial photos). Brackett soils have a USLE K factor of 0.37 which
includes the 90^th^ percentile of these soils in erodibility (Table 5).
The Brackett series is loamy, carbonatic, thermic, shallow Typic
Haplustepts. The soil consists of very shallow to shallow soils over
bedrock. They are well drained and moderately permeable soils that
formed in residuum over chalky limestone bedrock (USDA 2001). Slopes
range from 1 to 60 percent; however the most typical slope range for the
Brackett series on turf areas is 1-12 percent (USDA 2006; COA 2003).

Two zones are modeled for the purposes of PRZM scenarios: the cropped
zone and the soil zone. The cropped zone includes the region above the
soil surface. The soil zone includes the region below the land surface.
Turf, unlike most agricultural crops, can have a third important zone:
the thatch zone. The thatch zone is located between the cropped zone
(grass) and the soil. Thatch is made up of dead, undecomposed grass,
leaf, and root material. Thatch may be important in turf modeling
because it possesses hydrologic and pesticide fate properties which may
differ significantly from the other two zones described above. The
thatch zone may strongly influence movement of both water and pesticide
from the surface into the soil. Correctly representing the properties of
the thatch zone is therefore important to simulation of pesticide runoff
and leaching from turf areas. In order to appropriately model this
thatch layer, the soil zone is modified by adding a 2 cm deep layer of
thatch on top of the soil profile, with set properties (Table 4). A 2 cm
layer of thatch is typical for golf course fairways, but is probably
thicker than average for golf course greens (Mike Kenna, USGA, personal
communication). Modern greens built according to current USGA
specifications are designed to rapidly infiltrate water, and are built
upon sand/peat mixtures, with tile underdrainage. However, a large
fraction of the greens in this country are of the old-style push-up
variety, composed essentially of existing soil from the site, and
lacking underdrainage. For preliminary modeling purposes, turf will be
considered to be essentially generic, with no distinction made between
fairways, greens, tees, or residential lawns. For chemicals applied to
golf courses, the fraction of the total area composed of greens, tees,
and fairways may however be used to modify the results of a modeling
run, somewhat in the fashion of a percent cropped area (PCA) adjustment.
The approximate average percent areas (confirmed by Mike Kenna, USGA,
personal communication) are as follows: fairways, 23%; greens, 2%; tees,
2%. Thus if a pesticide is only used on greens and tees, for example,
the modeling results would be multiplied by a factor of 0.04. It is
possible that current PCA development efforts may produce PCAs for golf
courses, turf farms, and/or residential lawns that may also be used to
refine the results of modeling runs.

The meteorological station selected for this scenario is located in
Austin, Texas. This station is the closest available weather station
that includes the necessary data to run PRZM.

+---------------------+----------+-------------------------------------+
| **Table 1. PRZM     |          |                                     |
| 3.12 Climate and    |          |                                     |
| Time Parameters for |          |                                     |
| Barton Springs,     |          |                                     |
| TX.**               |          |                                     |
+---------------------+----------+-------------------------------------+
| **Parameter**       | *        | **Source/Comments**                 |
|                     | *Value** |                                     |
+---------------------+----------+-------------------------------------+
| Starting Date       | Jan. 1,  | Meteorological File from Austin, TX |
|                     | 1961     | (W13958)                            |
+---------------------+----------+-------------------------------------+
| Ending Date         | Dec. 31, | Meteorological File from Austin, TX |
|                     | 1990     | (W13958)                            |
+---------------------+----------+-------------------------------------+
| Pan Evaporation     | 0.69     | PRZM Manual Figure 5.1 (EPA 1998).  |
| Factor (PFAC)       |          |                                     |
+---------------------+----------+-------------------------------------+
| Snowmelt Factor     | 0.36     | PRZM Manual, Table 5.1 (EPA 1998).  |
| (SFAC)              |          |                                     |
+---------------------+----------+-------------------------------------+
| Minimum Depth of    | 25       | Mid point of range (20-30), PRZM    |
|                     |          | Manual, Figure 5.2 (EPA 1998).      |
| Evaporation (ANETD) |          |                                     |
+---------------------+----------+-------------------------------------+

+-----------------+----------+-----------------------------------------+
| **Table 2. PRZM |          |                                         |
| 3.12 Erosion    |          |                                         |
| and Landscape   |          |                                         |
| Parameters for  |          |                                         |
| Barton Springs  |          |                                         |
| Turf.**         |          |                                         |
+-----------------+----------+-----------------------------------------+
| **Parameter**   | *        | **Source/Comments**                     |
|                 | *Value** |                                         |
+-----------------+----------+-----------------------------------------+
| Method to       | 4 (MUSS) | Default value.                          |
| Calculate       |          |                                         |
| Erosion         |          |                                         |
| (ERFLAG)        |          |                                         |
+-----------------+----------+-----------------------------------------+
| USLE K Factor   | 0.37     | NRCS Soil Data Mart Database for        |
| (USLEK)         | tons     | Brackett-Rock outcrop-complex, 1-12%    |
|                 | EI^-1^\* | slopes, Travis County, TX.              |
|                 |          | (<http://soildatamart.nrcs.usda.gov/>). |
+-----------------+----------+-----------------------------------------+
| USLE LS Factor  | 1.34     | Calculated according to Haan and        |
| (USLELS)        |          | Barfield (1978) equation: LS =          |
|                 |          | ((λ/72.6)^m^)((430x^2^ + 30x +          |
|                 |          | 0.43)/6.613), where λ = slope length, x |
|                 |          | = SLP/100 and m = constant. In this     |
|                 |          | case, λ = 400 m (default value) and m = |
|                 |          | 0.5 (EPA 2004).                         |
+-----------------+----------+-----------------------------------------+
| USLE P Factor   | 0.5      | Set to 0.5 for 3-8% slopes(EPA 2004).   |
| (USLEP)         |          | Verified sediment loss with local       |
|                 |          | studies on turf areas.                  |
+-----------------+----------+-----------------------------------------+
| Field Area      | 10 ha    | Default value for area of standard farm |
| (AFIELD)        |          | pond.                                   |
+-----------------+----------+-----------------------------------------+
| NRCS Hyetograph | 4        | PRZM Manual, Figure 5.12 (EPA, 1998).   |
| (IREG)          |          |                                         |
+-----------------+----------+-----------------------------------------+
| Slope (SLP)     | 6 %      | Brackett-Rock Outcrop-Complex slope     |
|                 |          | range 1-12% (USDA 2006).                |
+-----------------+----------+-----------------------------------------+
| Hydraulic       | 356 m    | Default value for Pond (EPA, 2004)      |
| Length (HL)     |          |                                         |
+-----------------+----------+-----------------------------------------+
| Irrigation Flag | 1        | Nick Smithamn, Superintendent of Austin |
| (IRFLAG)        |          | Municipal Golf Courses, Date: 3-16-06,  |
|                 |          | Phone: 512-447-2616                     |
|                 |          |                                         |
|                 |          | 1 = year round                          |
+-----------------+----------+-----------------------------------------+
| Irrigation Type | 3        | Karen Stewart, Senior Water             |
| (IRTYP)         | (sp      | Conservation Specialist, City of Austin |
|                 | rinkler) | Water Utility, Date: 3/23/06, Phone:    |
|                 |          | 512-974-2978.                           |
|                 |          |                                         |
|                 |          | Irrigation Guidance for developing PRZM |
|                 |          | Scenario, Table 3; (June 15, 2005).     |
+-----------------+----------+-----------------------------------------+
| Leaching Factor | 0.1      | Irrigation Guidance for developing PRZM |
| (FLEACH)        |          | Scenario, Table 3; (June 15, 2005).     |
+-----------------+----------+-----------------------------------------+
| Fraction of     | 0.95     | Golf courses typically irrrigate ¼ to ½ |
| Water Capacity  |          | inch every night, no matter what, in    |
| when Irrigation |          | the summer. They may water less in the  |
| is Applied      |          | winter, every other night, and not when |
| (PCDEPL)        |          | a freeze is expected. (Karen Stewart,   |
|                 |          | Senior Water Conservation Specialist,   |
|                 |          | City of Austin Water Utility, Date:     |
|                 |          | 3/23/06, Phone: 512-974-2978.)          |
|                 |          |                                         |
|                 |          | Irrigation Guidance for developing PRZM |
|                 |          | Scenario, Table 3; (June 15, 2005).     |
+-----------------+----------+-----------------------------------------+
| Maximum Rate at | 0.053\   | ½ inch irrigation (see above for        |
| which           | cm       | PCDEPL)                                 |
| Irrigation is   | hr^-1^   |                                         |
| Applied         |          | Irrigation Guidance for developing PRZM |
| (RATEAP)        |          | Scenario, Table 1; (June 15, 2005).     |
+-----------------+----------+-----------------------------------------+
| \* EI = 100     |          |                                         |
| ft-tons \* in/  |          |                                         |
| acre\*hr        |          |                                         |
+-----------------+----------+-----------------------------------------+

+-----------------+----------+-----------------------------------------+
| **Table 3. PRZM |          |                                         |
| 3.12 Crop       |          |                                         |
| Parameters for  |          |                                         |
| Barton          |          |                                         |
| Springs -       |          |                                         |
| Turf.**         |          |                                         |
+=================+==========+=========================================+
| **Parameter**   | *        | **Source/Comments**                     |
|                 | *Value** |                                         |
+-----------------+----------+-----------------------------------------+
| Initial Crop    | 1        | Default value                           |
| (INICRP)        |          |                                         |
+-----------------+----------+-----------------------------------------+
| Initial Surface | 2        | 2 = cover crop. Cover crops are         |
| Condition       |          | typically planted on golf courses to    |
|                 |          | keep them green when bermudagrass goes  |
| (ISCOND)        |          | dormant (Karen Stewart, Senior Water    |
|                 |          | Conservation Specialist, City of Austin |
|                 |          | Water Utility, Date: 3/23/06, Phone:    |
|                 |          | 512-974-2978).                          |
+-----------------+----------+-----------------------------------------+
| Number of       | 1        | Set to number of crops in simulation.   |
| Different Crops |          | Default value.                          |
| (NDC)           |          |                                         |
+-----------------+----------+-----------------------------------------+
| Number of       | 30       | Set to weather data in meteorological   |
| Cropping        |          | file: Austin, TX (W13958).              |
| Periods (NCPDS) |          |                                         |
+-----------------+----------+-----------------------------------------+
| Maximum         | 0.1      | Taken from PAturf and FLturf scenarios. |
| rainfall        |          |                                         |
| interception    |          |                                         |
| storage of crop |          |                                         |
| (CINTCP)        |          |                                         |
+-----------------+----------+-----------------------------------------+
| Maximum Active  | 15 cm    | Nick Smithamn, Superintendent of Austin |
| Root Depth      |          | Municipal Golf Courses, Date: 3-16-06,  |
| (AMXDR)         |          | Phone: 512-447-2616                     |
+-----------------+----------+-----------------------------------------+
| Maximum Canopy  | 100      | Taken from PAturf and FLturf scenarios. |
| Coverage        |          |                                         |
| (COVMAX)        |          |                                         |
+-----------------+----------+-----------------------------------------+
| Soil Surface    | 2        | 2 = cover crop. Cover crops are         |
| Condition After |          | typically planted on golf courses to    |
| Harvest (ICNAH) |          | keep them green when bermudagrass goes  |
|                 |          | dormant (Karen Stewart, Senior Water    |
|                 |          | Conservation Specialist, City of Austin |
|                 |          | Water Utility, Date: 3/23/06, Phone:    |
|                 |          | 512-974-2978).                          |
+-----------------+----------+-----------------------------------------+
| Date of Crop    | 01/01/61 | Winter grass is planted on the greens   |
| Emergence       |          | so that they stay "green" year round.   |
|                 |          | The tees, fairways and roughs go        |
| (EMD, EMM,      |          | dormant from November to March (Nick    |
| IYREM)          |          | Smithamn, Superintendent of Austin      |
|                 |          | Municipal Golf Courses, Date: 3-16-06,  |
|                 |          | Phone: 512-447-2616).                   |
|                 |          |                                         |
|                 |          | The average first and last frost dates  |
|                 |          | of the winter season are November 10    |
|                 |          | and March 10, respectively (Karen       |
|                 |          | Stewart, Senior Water Conservation      |
|                 |          | Specialist, City of Austin Water        |
|                 |          | Utility, Date: 3/23/06, Phone:          |
|                 |          | 512-974-2978).                          |
|                 |          |                                         |
|                 |          | Dates set to model year round grass     |
|                 |          | coverage.                               |
+-----------------+----------+-----------------------------------------+
| Date of Crop    | 01/02/61 |                                         |
| Maturity        |          |                                         |
|                 |          |                                         |
| (MAD, MAM,      |          |                                         |
| IYRMAT)         |          |                                         |
+-----------------+----------+-----------------------------------------+
| Date of Crop    | 31/12/61 |                                         |
| Harvest         |          |                                         |
|                 |          |                                         |
| (HAD, HAM,      |          |                                         |
| IYRHAR)         |          |                                         |
+-----------------+----------+-----------------------------------------+
| Maximum Dry     | 0.0      | Not used in scenario.                   |
| Weight (WFMAX)  |          |                                         |
+-----------------+----------+-----------------------------------------+
| Maximum Canopy  | 2.5 cm   | Nick Smithamn, Superintendent of Austin |
| Height (HTMAX)  |          | Municipal Golf Courses, Date: 3-16-06,  |
|                 |          | Phone: 512-447-2616                     |
+-----------------+----------+-----------------------------------------+
| SCS Curve       | 74, 74,  | Table 2-2a, USDA 1986.                  |
| Number (CN)     | 74       |                                         |
|                 |          | Curve numbers are selected based on     |
|                 |          | Agood condition@ open space areas for   |
|                 |          | hydrologic soil group C. Same number    |
|                 |          | year round, since no cropping season.   |
|                 |          | This is consistent with other turf      |
|                 |          | scenarios (FL turf and PA turf).        |
+-----------------+----------+-----------------------------------------+
| Manning\'s N    | 0.110    | San Antonio Hay/Grass (I93HGHGC).       |
| Value (MNGN)    |          | Represents cover code 2 for first year  |
|                 |          | hay/grass, moderately dense cover.      |
+-----------------+----------+-----------------------------------------+
| USLE C Factor   | 0.000 -- | San Antonio Hay/Grass (I93HGHGC)        |
| (USLEC)         | 0.004    |                                         |
+-----------------+----------+-----------------------------------------+

+---------+-------------------+---------------------------------------+
| **Table |                   |                                       |
| 4. PRZM |                   |                                       |
| 3.12    |                   |                                       |
| "Bracke |                   |                                       |
| tt-Rock |                   |                                       |
| Ou      |                   |                                       |
| tcrop-C |                   |                                       |
| omplex" |                   |                                       |
| Soil    |                   |                                       |
| Par     |                   |                                       |
| ameters |                   |                                       |
| for     |                   |                                       |
| Barton  |                   |                                       |
| S       |                   |                                       |
| prings, |                   |                                       |
| TX -    |                   |                                       |
| Turf.** |                   |                                       |
+---------+-------------------+---------------------------------------+
| **Para  | **Value**         | **Source/Comments**                   |
| meter** |                   |                                       |
+---------+-------------------+---------------------------------------+
| Total   | 48 cm             | Brackett-Rock outcrop-complex, 1-12%  |
| Soil    |                   | slopes, Travis County, TX. NRCS Soil  |
| Depth   |                   | Data Mart Database                    |
| (CORED) |                   | (<                                    |
|         |                   | http://soildatamart.nrcs.usda.gov/>). |
|         |                   |                                       |
|         |                   | According to an extension agent       |
|         |                   | (Robert Martinez, phone: 512-454-2571 |
|         |                   | x3), golf courses between Bee Cave    |
|         |                   | and Austin TX reside primarily upon   |
|         |                   | Brackett soils.                       |
|         |                   |                                       |
|         |                   | Top horizon split in two and thatch   |
|         |                   | layer added as HORIZN 1. Soil         |
|         |                   | parameters of HORIZN 1 according to   |
|         |                   | EPA guidance on development of turf   |
|         |                   | scenario.                             |
|         |                   |                                       |
|         |                   | Additional data were listed for a     |
|         |                   | 5^th^ HORIZN. However, these were not |
|         |                   | included in this soil profile since   |
|         |                   | the 5^th^ HORIZN is composed of       |
|         |                   | bedrock.                              |
|         |                   |                                       |
|         |                   | PRZM Scenario Guidance (2004).        |
|         |                   |                                       |
|         |                   | Adjusted using the relationship % OC  |
|         |                   | = % Organic Matter/1.724 (Doucette    |
|         |                   | 2000).                                |
+---------+-------------------+---------------------------------------+
| Number  | 4                 |                                       |
| of      |                   |                                       |
| H       |                   |                                       |
| orizons |                   |                                       |
| (       |                   |                                       |
| NHORIZ) |                   |                                       |
+---------+-------------------+---------------------------------------+
| Horizon | 2 cm (HORIZN =1)  |                                       |
| Th      |                   |                                       |
| ickness | 10 cm (HORIZN =2) |                                       |
| (THKNS) |                   |                                       |
|         | 5 cm (HORIZN =3)  |                                       |
|         |                   |                                       |
|         | 31 cm (HORIZN =4) |                                       |
+---------+-------------------+---------------------------------------+
| Bulk    | 0.37 g/cm3        |                                       |
| Density | (HORIZN = 1)      |                                       |
| (BD)    |                   |                                       |
|         | 1.4 g/cm3 (HORIZN |                                       |
|         | =2)               |                                       |
|         |                   |                                       |
|         | 1.4 g/cm3 (HORIZN |                                       |
|         | =3)               |                                       |
|         |                   |                                       |
|         | 1.43 g/cm3        |                                       |
|         | (HORIZN =4)       |                                       |
+---------+-------------------+---------------------------------------+
| Initial | 0.47 cm3/cm3      |                                       |
| Water   | (HORIZN =1)       |                                       |
| Content |                   |                                       |
| (THETO) | 0.28 cm3/cm3      |                                       |
|         | (HORIZN =2)       |                                       |
|         |                   |                                       |
|         | 0.28 cm3/cm3      |                                       |
|         | (HORIZN =3)       |                                       |
|         |                   |                                       |
|         | 0.252 cm3/cm3     |                                       |
|         | (HORIZN =4)       |                                       |
+---------+-------------------+---------------------------------------+
| Comp    | 0.1 cm (HORIZN =  |                                       |
| artment | 1)                |                                       |
| Th      |                   |                                       |
| ickness | 5 cm (HORIZN = 2) |                                       |
| (DPN)   |                   |                                       |
|         | 5 cm (HORIZN = 3) |                                       |
|         |                   |                                       |
|         | 1 cm (HORIZN = 4) |                                       |
+---------+-------------------+---------------------------------------+
| Field   | 0.47 cm3/cm3      |                                       |
| C       | (HORIZN =1)       |                                       |
| apacity |                   |                                       |
| (THEFC) | 0.28 cm3/cm3      |                                       |
|         | (HORIZN =2)       |                                       |
|         |                   |                                       |
|         | 0.28 cm3/cm3      |                                       |
|         | (HORIZN =3)       |                                       |
|         |                   |                                       |
|         | 0.252 cm3/cm3     |                                       |
|         | (HORIZN =4)       |                                       |
+---------+-------------------+---------------------------------------+
| Wilting | 0.27 cm3/cm3      |                                       |
| Point   | (HORIZN =1)       |                                       |
| (THEWP) |                   |                                       |
|         | 0.164 cm3/cm3     |                                       |
|         | (HORIZN =2)       |                                       |
|         |                   |                                       |
|         | 0.164 cm3/cm3     |                                       |
|         | (HORIZN =3)       |                                       |
|         |                   |                                       |
|         | 0.145 cm3/cm3     |                                       |
|         | (HORIZN =4)       |                                       |
+---------+-------------------+---------------------------------------+
| Organic | 7.5 % (HORIZN =   |                                       |
| Carbon  | 1)                |                                       |
| Content |                   |                                       |
| (OC)    | 1.16 % (HORIZN    |                                       |
|         | =2)               |                                       |
|         |                   |                                       |
|         | 1.16 % (HORIZN    |                                       |
|         | =3)               |                                       |
|         |                   |                                       |
|         | 0.73 % (HORIZN    |                                       |
|         | =4)               |                                       |
+---------+-------------------+---------------------------------------+

  ---------------------------------------------------------------------------------------------------------------
  **Table 5.                                                                                             
  Soils                                                                                                  
  co-located                                                                                             
  with turf                                                                                              
  areas in the                                                                                           
  Barton                                                                                                 
  Spring                                                                                                 
  Segment                                                                                                
  based on                                                                                               
  USDA 2006                                                                                              
  soils data                                                                                             
  and COA 2003                                                                                           
  land use                                                                                               
  data.**                                                                                                
  ------------ ----------- -------- ------------ -------- ----------- -------- ------- -------- -------- --------
  **Soil**     **Total     **%      **Drainage   **KF**   **Slope**   **pH**   **OM\   **Sand   **Silt   **Clay
               Acreage**   Area**   Class**                                    (%)**   (%)**    (%)**    (%)**

  Tarrant      2,056.44    28.7%    D            0.32     0 - 50      8        5       22       28       50

  Brackett     1,556.57    21.7%    C            0.37     1 - 60      8        2       34       37       28

  Speck        1,393.72    19.4%    D            0.32     1 - 5       7        2       34       37       30

  Volente      615.26      8.6%     C            0.32     1 - 8       8        3       7        32       39

  Alluvial     488.06      6.8%     A            0.15     0 - 1       8        1       90       0        5
  land                                                                                                   

  Crawford     178.58      2.5%     D            0.32     0 - 2       7        2       22       28       50

  San Saba     156.55      2.2%     D            0.32     0 - 2       8        3       18       29       53

  Purves       90.19       1.3%     D            0.32     1 - 5       8        3       6        47       48

  Doss         86.66       1.2%     D            0.32     1 - 5       8        2       7        49       44

  Heiden       75.48       1.1%     D            0.32     1 - 8       8        3       22       28       50

  Denton       63.10       0.9%     D            0.32     1 - 5       8        3       6        48       46

  Bergstrom    55.76       0.8%     B            0.32     0 - 2       8        2       7        62       31

  Comfort      54.35       0.8%     D            0.32     1 - 8       8        6       28       29       43

  Ferris       49.02       0.7%     D            0.32     8 - 20      8        1       18       29       53

  Hardeman     48.20       0.7%     B            0.24     3 - 12      8        1       66       20       14

  Altoga       32.09       0.4%     C            0.32     2 - 8       8        1       7        48       45

  Eddy         26.77       0.4%     C            0.32     1 - 6       8        1       38       36       26

  Austin       26.67       0.4%     C            0.32     1 - 6       8        3       7        48       45

  Sunev        24.05       0.3%     B            0.32     1 - 3       8        2       34       37       30

  Bolar        20.17       0.3%     C            0.32     1 - 3       8        2       34       37       30

  Houston      15.65       0.2%     D            0.32     0 - 8       8        3       17       28       55
  Black                                                                                                  

  Lewisville   14.63       0.2%     B            0.32     0 - 2       8        2       8        51       41

  Krum         13.15       0.2%     D            0.32     1 - 3       8        2       26       29       45

  Patrick      12.24       0.2%     B            0.32     1 - 10      8        2       28       29       43

  Travis       5.36        0.1%     C            0.24     1 - 8       7        1       66       19       15

  Oakalla      4.46        0.1%     B            0.32     0 - 1       8        4       18       48       34

  Real         3.45        0.0%     D            0.28     1 - 8       8        6       36       34       31

  Gaddy        1.54        0.0%     A            0.17     0 - 1       8        0       84       7        10

  Rumple       1.11        0.0%     C            0.32     1 - 8       7        2       34       37       30

  Castephen    \<1         0.0%     C            0.32     3 - 5       8        2       19       48       34

  Gruene       \<1         0.0%     D            0.28     1 - 5       8        2       28       29       43

  Tarpley      \<1         0.0%     D            0.32     1 - 3       7        3       30       30       40
  ---------------------------------------------------------------------------------------------------------------

***Sensitive Parameter Uncertainties***

[Slope]{.underline}

Depending upon the specific golf course and upon the portion of that
golf course, slopes can range significantly. In order to obtain a slope
value that would be representative of a BSS golf course, the midpoint
was used for the slope range (1 to 12%) of the of Brackett soil with the
greatest extent on golf course areas. The slope value of 6% is
representative of a slope that would be found for a soil type that
overlaps with golf courses in BSS. Also, this selection is not disputed
by existing turf scenarios. The SLP values of FL turf and PA turf are 2
and 12, respectively. The slope of 6% for BSSTurf falls within this
range.

Since the overall slope of this soil type ranges from 1 to 60 percent,
the SLP value could be higher. If the overall slope range (1 to 60%)
were considered for the conceptual model of this scenario, the default
value of 12% (corresponding to hay crops and orchards) could be used.
This would result in a higher USLE LS factor, and thus, a higher runoff
potential.

[USLE C Factor and Manning's N Value]{.underline}

The RUSLE Project did not include data that were specific to an area
within the BSS. Therefore, USLE C Factor and Manning's N values were
selected from data representing the closest available climate station,
which was San Antonio. For USLEC and Manning's N values, the file for
San Antonio hay/grass. Sediment yield were compared to observed data for
golf courses in the area and are reasonable. Sediment yield are high end
relative to observed data.

**References**

City of Austin (COA). 2003. Unpublished Land Use Data.
http://www.ci.austin.tx.us/landuse/. Accessed 15 February 2006.

Duble, R.L. 2004. Bermudagrass, The Sports Turf of the South. Texas
cooperative extension. Posted 3/10/2004. Available at:
<http://extension-horticulture.tamu.edu/plantanswers/turf/publications/bermuda.html>

EPA. 1998. Carsel, R.F., J.C. Imhoff, P.R. Hummel, J.M. Cheplick, and
A.S. Donigian, Jr. PRZM-3, A Model for Predicting Pesticide and Nitrogen
Fate in the Crop Root and Unsaturated Soil Zones: Users Manual for
Release 3.0. National Exposure Research Laboratory, Office of Research
and Development, U.S. Environmental Protection Agency, Athens, GA.

EPA. 2004. Pesticide Root Zone Model (PRZM) Field and Orchard Crop
Scenarios: Guidance for Selecting Field Crop and Orchard Scenario Input
Parameters. November 15, 2001; Revisions July 2004.

EPA. 2005. Irrigation Guidance for developing PRZM Scenario. June 15,
2005.

Haan, C.T. and B.J. Barfield. 1978. Hydrology and Sedimentology of
Surface Mined Lands. Office of Continuing Education and Extension,
College of Engineering, University of Kentucky, Lexington, Kentucky
40506. pp. 286.

Martinez, R. 2006. NRCS officer for Travis County. Personal
Communication, March 22, 2006.

Smithamn, N. Superintendent of Austin Municipal Golf Courses. Personal
communication, March 16, 2006.

Stewart, K. Senior Water Conservation Specialist, City of Austin Water
Utility. Personal communication, March 23, 2006.

USDA. 2006. Soil Survey Areas of Hays Counties, Texas. U.S. Department
of Agriculture, Natural Resources Conservation Service (NRCS), Soil Data
Mart. March 1, 2006. Online at:
[http://soildatamart.nrcs.usda.gov](http://soildatamart.nrcs.usda.gov/).

USDA. 1986. Urban Hydrology for Small Watersheds. United States
Department of Agriculture, Natural Resources Communication Service.
Technical Release 55.

USDA. 2001. Official Series Description. Brackett Series. Information
from the website:
<http://ortho.ftw.nrcs.usda.gov/osd/dat/B/BRACKETT.html>.

USGS, National Mapping Division, Rocky Mountain Mapping Center. 2003.
Edwards Aquifer Land Use / Land Cover. Denver, Colorado.