**Barton Springs Meadow**

This scenario is intended to represent a meadow that may include
cultivation of herbaceous, non-grass animal feeds (IR4 generalized crop
group #18 including forage, fodder, straw, and hay). The USDA census of
agriculture (USDA 1997, 2002) indicates that hay of varying types is
grown extensively in Travis and Hays Counties (Table 6). Discussions
with extension agents in Hays and Travis counties indicated that some
cultivation of sorghum hay, hay grazer, and sweet sorghum does occur in
the Barton Springs Segment (BSS) of the Edward Aquifer. Bermuda grass is
also planted but is primarily for grazing and not harvested (Perez
2006). Most of this type of crop is for livestock grazing (Davis, 2006).
Crop parameters for this scenario were chosen to be reflective of hay
and grass in the BSS.

Soils were selected based on the extent within herbaceous planted areas
(USGS 2003) in BSS and the potential to yield high-end runoff and
erosion. Based on a geospatial analysis of soils (USDA 2006) and land
use data (USGS 2003) for herbaceous planted areas, Brackett soils were
chosen to represent meadow areas in the BSS (Table 5). It should be
noted that much of the Planted/cultivated land is highly managed
pastureland. Therefore, the location of Brackett soils was also
cross-checked with aerial photography (TWDB 2004) and a local expert to
ensure that the soil chosen coincided with herbaceous planted areas
where pesticides would reasonably be applied. A local soil expert
confirmed that Brackett soils are extensive soil types of meadows in the
BSS (Perez, 2006)

The Brackett series was selected because it is a benchmark soil, is
highly representative of meadow areas in the BSS, and represents the
90^th^ percentile of vulnerability, drainage, erodibility, and slope.
The Brackett series account for 4.5% of natural herbaceous areas (Table
5). Brackett is a Hydrologic Group C soil which account for
approximately 49% of natural herbaceous soils in drainage. Brackett
soils have a USLE K factor of 0.37 which includes the 90^th^ percentile
of these soils in erodibility (Table 5). Slopes range from 1 to 60
percent (Soil Survey Staff, 2006); however the most typical range for
the Brackett series in rangeland areas is 1-8 percent (USDA 2006; USGS
2003). Soil parameters for the "Brackett-Rock outcrop-Comfort complex, 1
to 8 percent slopes" were selected from Soil Data Mart to parameterize
this scenario since this soil type is the most extensive soil collocated
with herbaceous planted areas within the Brackett series (USDA 2006;
USGS 2003). Data from Hays County were selected since the majority of
this landcover is located in this county.

The meteorological station selected for this scenario is located in
Austin, Texas. This station is the closest available weather station
that includes data required for 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   | 25       | Mid point of range (20-30), PRZM        |
| of              |          | Manual, Figure 5.2 (EPA 1998).          |
|                 |          |                                         |
| Evaporation     |          |                                         |
| (ANETD)         |          |                                         |
+-----------------+----------+-----------------------------------------+

+-----------------+----------+-----------------------------------------+
| **Table 2. PRZM |          |                                         |
| 3.12 Erosion    |          |                                         |
| and Landscape   |          |                                         |
| Parameters for  |          |                                         |
| Barton          |          |                                         |
| Springs -       |          |                                         |
| Meadow.**       |          |                                         |
+-----------------+----------+-----------------------------------------+
| **Parameter**   | *        | **Source/Comments**                     |
|                 | *Value** |                                         |
+-----------------+----------+-----------------------------------------+
| Method to       | 4 (MUSS) | Default value.                          |
| Calculate       |          |                                         |
| Erosion         |          |                                         |
| (ERFLAG)        |          |                                         |
+-----------------+----------+-----------------------------------------+
| USLE K Factor   | 0.37     | Brackett-Rock Outcrop-Comfort Complex   |
| (USLEK)         | tons     | Soil (USDA 2006).                       |
|                 | EI^-1^\* |                                         |
+-----------------+----------+-----------------------------------------+
| USLE LS Factor  | 0.69     | 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 = |
|                 |          | 0.4 (EPA 2004).                         |
+-----------------+----------+-----------------------------------------+
| USLE P Factor   | 1        | No contour plowing assumed.             |
| (USLEP)         |          |                                         |
+-----------------+----------+-----------------------------------------+
| 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)     | 4 %      | Brackett-Rock Outcrop-Comfort Complex   |
|                 |          | Soil Slope range 1-8% (USDA 2006).      |
+-----------------+----------+-----------------------------------------+
| Hydraulic       | 356 m    | Default value for Pond (EPA, 2004)      |
| Length (HL)     |          |                                         |
+-----------------+----------+-----------------------------------------+
| Irrigation Flag | 0        | Cris Perez, NRCS - District             |
| (IRFLAG)        |          | Conservationist                         |
|                 |          |                                         |
|                 |          | Date: 3-16-06, Phone: 512-392-4050 x3   |
+-----------------+----------+-----------------------------------------+
| \* EI = 100     |          |                                         |
| ft-tons \* in/  |          |                                         |
| acre\*hr        |          |                                         |
+-----------------+----------+-----------------------------------------+

+-----------------------+--------------+------------------------------+
| **Table 3. PRZM 3.12  |              |                              |
| Crop Parameters for   |              |                              |
| Barton Springs -      |              |                              |
| Meadow.**             |              |                              |
+-----------------------+--------------+------------------------------+
| **Parameter**         | **Value**    | **Source/Comments**          |
+-----------------------+--------------+------------------------------+
| Initial Crop (INICRP) | 1            | Default value                |
+-----------------------+--------------+------------------------------+
| Initial Surface       | 3            | Cris Perez, NRCS - District  |
| Condition             |              | Conservationist              |
|                       |              |                              |
| (ISCOND)              |              | Date: 3-16-06, Phone:        |
|                       |              | 512-392-4050 x3              |
|                       |              |                              |
|                       |              | Residue is left on a field   |
|                       |              | until the next year.         |
+-----------------------+--------------+------------------------------+
| Number of Different   | 1            | Set to number of crops in    |
| Crops (NDC)           |              | simulation. Default value.   |
+-----------------------+--------------+------------------------------+
| Number of Cropping    | 30           | Set to weather data in       |
| Periods (NCPDS)       |              | meteorological file: Austin, |
|                       |              | TX (W13958).                 |
+-----------------------+--------------+------------------------------+
| Maximum rainfall      | 0.25         | Table 5-4 PRZM manual for    |
| interception storage  |              | moderate density crops (EPA, |
| of crop (CINTCP)      |              | 1998). Consistent with       |
|                       |              | alfalfa scenarios.           |
+-----------------------+--------------+------------------------------+
| Maximum Active Root   | 41           | Cris Perez, NRCS - District  |
| Depth (AMXDR)         |              | Conservationist              |
|                       |              |                              |
|                       |              | Date: 3-16-06, Phone:        |
|                       |              | 512-392-4050 x3              |
|                       |              |                              |
|                       |              | Roots reach 8-16".           |
+-----------------------+--------------+------------------------------+
| Maximum Canopy        | 100          | Cris Perez, NRCS - District  |
| Coverage (COVMAX)     |              | Conservationist              |
|                       |              |                              |
|                       |              | Date: 3-16-06, Phone:        |
|                       |              | 512-392-4050 x3              |
+-----------------------+--------------+------------------------------+
| Soil Surface          | 3            | Cris Perez, NRCS - District  |
| Condition After       |              | Conservationist              |
| Harvest (ICNAH)       |              |                              |
|                       |              | Date: 3-16-06, Phone:        |
|                       |              | 512-392-4050 x3              |
|                       |              |                              |
|                       |              | Residue is left on a field   |
|                       |              | after harvest.               |
+-----------------------+--------------+------------------------------+
| Maximum Canopy Height | 152 cm       | Cris Perez NRCS - District   |
| (HTMAX)               |              | Conservationist              |
|                       |              |                              |
|                       |              | Date: 3-16-06, Phone:        |
|                       |              | 512-392-4050 x3              |
|                       |              |                              |
|                       |              | (Max height: 4-5 ft)         |
+-----------------------+--------------+------------------------------+
| Date of Crop          | 01/03/61     | Cris Perez, NRCS - District  |
| Emergence             |              | Conservationist              |
|                       |              |                              |
| (EMD, EMM, IYREM)     |              | Date: 3-16-06, Phone:        |
|                       |              | 512-392-4050 x3              |
|                       |              |                              |
|                       |              | Grass is planted February    |
|                       |              | --March, It is first         |
|                       |              | harvested April-May. The     |
|                       |              | crop may be cut 1-2 more     |
|                       |              | times until September.       |
+-----------------------+--------------+------------------------------+
| Date of Crop Maturity | 01/04/61     |                              |
|                       |              |                              |
| (MAD, MAM, IYRMAT)    |              |                              |
+-----------------------+--------------+------------------------------+
| Date of Crop Harvest  | 01/09/61     |                              |
|                       |              |                              |
| (HAD, HAM, IYRHAR)    |              |                              |
+-----------------------+--------------+------------------------------+
| Maximum Dry Weight    | 0.0          | Not used in scenario.        |
| (WFMAX)               |              |                              |
+-----------------------+--------------+------------------------------+
| SCS Curve Number (CN) | 84, 79, 82   | Gleams Manual Table H-4,     |
|                       |              | meadow, hydrologic group C,  |
|                       |              | good condition (USDA, 2000)  |
+-----------------------+--------------+------------------------------+
| Manning\'s N Value    | 0.110        | San Antonio Hay/Grass        |
| (MNGN)                |              | (I93HGHGC). This file        |
|                       |              | incorporates tillage and has |
|                       |              | a cover code (2)             |
|                       |              | representing first year      |
|                       |              | meadow/hay. According to     |
|                       |              | Cris Perez, these fields are |
|                       |              | tilled for new crops in      |
|                       |              | Jan/Feb.                     |
+-----------------------+--------------+------------------------------+
| USLE C Factor (USLEC) | 0.000 --     | San Antonio Hay/Grass        |
|                       | 0.004        | (I93HGHGC)                   |
+-----------------------+--------------+------------------------------+

+---------+-------------------+---------------------------------------+
| **Table |                   |                                       |
| 4. PRZM |                   |                                       |
| 3.12    |                   |                                       |
| Bracke  |                   |                                       |
| tt-Rock |                   |                                       |
| O       |                   |                                       |
| utcrop- |                   |                                       |
| Comfort |                   |                                       |
| Complex |                   |                                       |
| Soil    |                   |                                       |
| Par     |                   |                                       |
| ameters |                   |                                       |
| for     |                   |                                       |
| Barton  |                   |                                       |
| Sp      |                   |                                       |
| rings - |                   |                                       |
| me      |                   |                                       |
| adow.** |                   |                                       |
+---------+-------------------+---------------------------------------+
| **Para  | **Value**         | **Source/Comments**                   |
| meter** |                   |                                       |
+---------+-------------------+---------------------------------------+
| Total   | 43 cm             | NRCS Soil Data Mart Database, Hays    |
| Soil    |                   | County, for Brackett-Rock             |
| Depth   |                   | outcrop-Comfort complex, 1 to 8       |
| (CORED) |                   | percent slopes.                       |
|         |                   | (<                                    |
|         |                   | http://soildatamart.nrcs.usda.gov/>). |
|         |                   |                                       |
|         |                   | According to an extension agent (Cris |
|         |                   | Perez), meadows reside on a variety   |
|         |                   | of soils. Brackett is one of the more |
|         |                   | extensive soil types of meadows in    |
|         |                   | this area.                            |
|         |                   |                                       |
|         |                   | Additional data were listed for a     |
|         |                   | 4^th^ HORIZN. However, these were not |
|         |                   | included in this soil profile since   |
|         |                   | the 4^th^ HORIZN is composed of       |
|         |                   | bedrock.                              |
|         |                   |                                       |
|         |                   | PRZM Scenario Guidance (2004).        |
|         |                   |                                       |
|         |                   | Adjusted using the relationship % OC  |
|         |                   | = % Organic Matter/1.724 (Doucette    |
|         |                   | 2000).                                |
+---------+-------------------+---------------------------------------+
| Number  | 3                 |                                       |
| of      |                   |                                       |
| H       |                   |                                       |
| orizons |                   |                                       |
| (       |                   |                                       |
| NHORIZ) |                   |                                       |
+---------+-------------------+---------------------------------------+
| Horizon | 10 cm (HORIZN =1) |                                       |
| Th      |                   |                                       |
| ickness | 5 cm (HORIZN =2)  |                                       |
| (THKNS) |                   |                                       |
|         | 28 cm (HORIZN =3) |                                       |
+---------+-------------------+---------------------------------------+
| Bulk    | 1.4 g/cm3 (HORIZN |                                       |
| Density | =1)               |                                       |
| (BD)    |                   |                                       |
|         | 1.4 g/cm3 (HORIZN |                                       |
|         | =2)               |                                       |
|         |                   |                                       |
|         | 1.4 g/cm3 (HORIZN |                                       |
|         | =3)               |                                       |
+---------+-------------------+---------------------------------------+
| Initial | 0.28 cm3/cm3      |                                       |
| Water   | (HORIZN =1)       |                                       |
| Content |                   |                                       |
| (THETO) | 0.28 cm3/cm3      |                                       |
|         | (HORIZN =2)       |                                       |
|         |                   |                                       |
|         | 0.251 cm3/cm3     |                                       |
|         | (HORIZN =3)       |                                       |
+---------+-------------------+---------------------------------------+
| Comp    | 0.1 cm (HORIZN    |                                       |
| artment | =1)               |                                       |
| Th      |                   |                                       |
| ickness | 5 cm (HORIZN =2)  |                                       |
| (DPN)   |                   |                                       |
|         | 4 cm (HORIZN =3)  |                                       |
+---------+-------------------+---------------------------------------+
| Field   | 0.28 cm3/cm3      |                                       |
| C       | (HORIZN =1)       |                                       |
| apacity |                   |                                       |
| (THEFC) | 0.28 cm3/cm3      |                                       |
|         | (HORIZN =2)       |                                       |
|         |                   |                                       |
|         | 0.251 cm3/cm3     |                                       |
|         | (HORIZN =3)       |                                       |
+---------+-------------------+---------------------------------------+
| Wilting | 0.164 cm3/cm3     |                                       |
| Point   | (HORIZN =1)       |                                       |
| (THEWP) |                   |                                       |
|         | 0.164 cm3/cm3     |                                       |
|         | (HORIZN =2)       |                                       |
|         |                   |                                       |
|         | 0.142 cm3/cm3     |                                       |
|         | (HORIZN =3)       |                                       |
+---------+-------------------+---------------------------------------+
| Organic | 1.16 % (HORIZN    |                                       |
| Carbon  | =1)               |                                       |
| Content |                   |                                       |
| (OC)    | 1.16 % (HORIZN    |                                       |
|         | =2)               |                                       |
|         |                   |                                       |
|         | 0.73 % (HORIZN    |                                       |
|         | =3)               |                                       |
+---------+-------------------+---------------------------------------+

  -------------------- ----------- ----------- ------------ ---------- --------- -------- ------- -------- -------- --------
  **Table 5. Soils                                                                                                  
  co-located with                                                                                                   
  planted/cultivated                                                                                                
  herbaceous areas of                                                                                               
  the Barton Spring                                                                                                 
  Segment based on                                                                                                  
  USDA 2006 soils data                                                                                              
  and USGS 2003 land                                                                                                
  use data. Bold font                                                                                               
  indicates a                                                                                                       
  benchmark soil.**                                                                                                 

  **Soil**             **Total     **%         **Drainage   **KF**     **Slope   **pH**   **OM    **Sand   **Silt   **Clay
                       Acreage**   Area^a^**   Class**                 (%)**              (%)**   (%)**    (%)**    (%)**

  Doss                 1,501       18.6        D            0.32       1 - 5     8        2       7        49       44

  Krum                 1,139       14.1        D            0.32       0 - 1     8        2       26       29       45

  Sunev                774         9.6         B            0.32       0 - 1     8        2       18       52       30

  **Denton**           **421**     **5.2**     **D**        **0.32**   **1 - 3** **8**    **3**   **6**    **48**   **46**

  **Brackett**         **367**     **4.5**     **C**        **0.37**   **1 -     **8**    **2**   **34**   **38**   **28**
                                                                       12**                                         

  **Austin**           **367**     **4.5**     **C**        **0.32**   **1 - 3** **8**    **3**   **7**    **48**   **45**

  Heiden               352         4.4         D            0.32       1 - 3     8        3       22       28       50

  **Bolar**            **343**     **4.2**     **C**        **0.32**   **1 - 3** **8**    **2**   **34**   **37**   **30**

  **Lewisville**       **322**     **4.0**     **B**        **0.32**   **0 - 1** **8**    **2**   **8**    **51**   **41**

  **Houston Black**    **311**     **3.8**     **D**        **0.32**   **1 - 3** **8**    **3**   **17**   **28**   **55**

  Purves               310         3.8         D            0.32       1 - 5     8        3       23       29       48

  Tarpley              216         2.7         D            0.32       1 - 3     7        3       30       30       40

  Anhalt               199         2.5         D            0.32       1 - 3     7        3       26       29       45

  Volente              194         2.4         C            0.32       1 - 8     8        3       7        54       39

  **Crawford**         **186**     **2.3**     **D**        **0.32**   **0 - 1** **7**    **2**   **22**   **28**   **50**

  Seawillow            180         2.2         B            0.32       1 - 3     8        1       35       34       31

  Gruene               165         2.0         D            0.28       1 - 5     8        2       28       29       43

  Branyon              120         1.5         D            0.32       0 - 1     8        3       22       28       50

  Real                 115         1.4         D            0.28       1 - 8     8        6       36       34       31

  Speck                115         1.4         D            0.32       1 - 3     7        2       34       37       30

  Rumple               96          1.2         C            0.32       1 - 8     7        2       34       37       30

  Castephen            69          0.9         C            0.32       3 - 5     8        2       34       32       34

  San Saba             68          0.8         D            0.32       1 - 2     8        3       18       29       53

  Comfort              45          0.6         D            0.32       1 - 8     8        6       28       29       43

  Medlin               32          0.4         D            0.32       1 - 8     8        2       22       28       50

  Oakalla              27          0.3         B            0.32       0 - 1     8        4       18       48       34

  **Tarrant**          **13**      **0.2**     **D**        **0.32**   **5 -     **8**    **5**   **22**   **28**   **50**
                                                                       18**                                         

  Orif                 10          0.1         A            0.28       0 - 1     8        2       82       9        9

  Boerne               7           0.1         B            0.28       1 - 3     8        1       65       20       16

  Patrick              7           0.1         B            0.32       2 - 5     8        2       28       29       43

  Tinn                 7           0.1         D            0.32       0 - 1     8        3       22       28       50

  Urban land           5           0.1         D            0.00       0 - 5     0        0       0        0        0

  Alluvial land        2           0.0         A            0.15       0 - 1     8        1       90       0        5

  Eddy                 2           0.0         C            0.32       3 - 6     8        1       38       36       26

  Eckrant              0           0.0         D            0.32       8 - 40    8        7       22       28       50

  ^a^ percent of all                                                                                                
  soils located in                                                                                                  
  herbaceous planted                                                                                                
  areas.\                                                                                                           
  OM, pH, Sand, Silt,                                                                                               
  Clay values based on                                                                                              
  "representative"                                                                                                  
  values in Soil Data                                                                                               
  Mart.                                                                                                             
  -------------------- ----------- ----------- ------------ ---------- --------- -------- ------- -------- -------- --------

  ------------------------------- ----------- ----------- ------------ -----------
  **Table 6. Acreage of hay crops                                      
  in Hays and Travis Counties, TX                                      
  (USDA 1997, 2002). NA is not                                         
  available.**                                                         

  **Crop**                        **HAYS**                **TRAVIS**   

                                  **1997      **2002      **1997       **2002
                                  Harvested   Harvested   Harvested    Harvested
                                  Acres**     Acres**     Acres**      Acres**

  Hay - All Hay Including         NA          7657        NA           20471
  Alfalfa, Other Tame, Small                                           
  Grain, And Wild                                                      

  All Haylage, Grass Silage, And  140         229         769          357
  Greenchop                                                            

  Forage - Land Used For All Hay  NA          7855        NA           20367
  And All Haylage, Grass Silage,                                       
  And Greenchop                                                        

  Other Haylage, Grass Silage,    NA          229         NA           357
  And Greenchop                                                        

  Other Tame Hay                  8287        5358        14020        16737

  Small Grain Hay                 600         NA          943          2219

  Wild Hay                        840         1228        NA           1411

  Alfalfa Hay                     65          NA          NA           104
  ------------------------------- ----------- ----------- ------------ -----------

**References\
**

Davis, B. 2006. Texas Cooperative Extension. Hays County Extension
Agent. Agriculture and Natural Resources. Personal communication. 17
March 2006.

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. 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.

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.

Perez, C. 2006. NRCS - District Conservationist. Personal communication.
March 17 & 20, 2006.

Soil Survey Staff, Natural Resources Conservation Service, United States
Department of Agriculture. Official Soil Series Descriptions \[Online
WWW\]. Available URL:
\"http://soils.usda.gov/technical/classification/osd/index.html\"
\[Accessed 6 March 2006\].

Texas Water Development Board (TWDB), Texas Natural Resource Information
System ([http://www.tnris.state.tx.us/]{.underline}). 2004. 1-Meter
Aerial Photography for Travis and Hays Counties. Accessed March 3, 2006.

USDA 2000. Knisel, W.G., and Davis, F.M., 2000, GLEAMS: Groundwater
Loading Effects of Agricultural Management Systems, Version 3.0:
Agricultural Research Service, U.S. Department of Agriculture,
Publication No. SEWRL-WGK/FMD-050199, 191 p.

USDA. 1997. 1997 Census of Agriculture. U.S. Department of Agriculture,
National Agricultural Statistics Service. Accessed March 2006. Online
at: http://www.nass.usda.gov/index.asp.

USDA. 2002. 2002 Census of Agriculture. U.S. Department of Agriculture,
National Agricultural Statistics Service. Accessed March 2006. Online
at: <http://www.nass.usda.gov/index.asp>.

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. 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.