Letter Report by SWET, Inc. 1 August 8, 2006

Ms. Joyce Zhang South Florida Water Management District

3301 Gun Club Road West Palm Beach, Florida 33406

SUBJECT: Letter Report Entitled: Phosphorus Reduction Performance and Implementation Costs under BMPs and Technologies in th e Lake Okeechobee Protection Plan Area

Dear Joyce:

I have completed my re-evaluation of th e phosphorus (P) reduction performance and implementation costs that Dr. Harper and I prev iously submitted to Ms. Benita Whalen as a letter report on October 20, 2003. The primary purpose of this re-evaluation was to update the values in the previous report and include one additional agricultural land use category (ornamentals) and separate range/woodland past ures from unimproved pastures. The urban land use category was also broken out into more detail.

To complete these tasks, a workshop was organi zed and held with lead ing agricultural experts with specific knowledge of BM P implementation practices and effectiveness. The workshop was held in Gainesville, FL on May 23, 2006 w ith the following attendees: Joyce Zhang (SFWMD), Drs. Don Graetz and Tom Obreza (Soil Science, UF), Drs. Roger Nordstedt, Ken Campbell and Sanjay Shukla (ABE, UF), Dr. Ed Hanlon (Director, SWFREC, UF), and Dr. Patrick Bohlen, Director of Re search, MacArthur Agro-ecology Research Center. Dr. Ike Ezenwa (Agronomy, UF) was later contacted with regards to sand-land sugarcane production practices. The workshop was invaluable to determining the latest research and crop management practices for the primary crops grown in the Lake Okeechobee basins. The appropriate values for existing and BMPs pr actices for each agricultural land use were discussed in detail with updated values bei ng developed by group consensus. The following are the primary changes developed by the group:

1. Table 1 from the previous report was reorgani zed to eliminate conf usion for the listed primary land uses. Also, one of the land uses (ornamental), which was previously under other land uses, was considered signi ficant enough to be analyzed separately during this assessment.

2. The stormwater retention and wetland re storation BMPs were separated with significantly less emphasis being placed on wetland restoration P reductions due to

recent field data that show these restorati on projects are less effective than originally thought. It is also important to note that it is assume d that stormwater retention systems will not impact in-field water tabl es because if they did, then they could adversely affect P loads. Also, it is assumed that the retention ponds are not

constructed on fields with hist oric high P levels, or if they are the land is treated with alum prior to flooding.

3. Existing unit loads and BMP reductions fr om unimproved pastures were redone so

that there would be a difference betw een unimproved pasture and range/woodlandLetter Report by SWET, Inc. 2 pastures. The workshop group agreed that the typical definition of unimproved pasture has animal densities and grass and fertility practices somewhere in between the improved and range/woodland pastures cate gories. Table values were adjusted accordingly.

4. The land use category of ornamentals was added and assumed to be an intensive ornamental nursery operation, but it is recognized that ornamental field crops, such as caladiums, may also be mapped under this ca tegory. However, ornamental field crops would be more similar to row crops than nur series, and therefore it is suggested that for now the row crops table be used for ornamental field crops.

5. An assessment table for the land use categor y of field crops was added and assumed to be a hay field that is fertilized with P. The workshop group helped develop estimates for existing and BMP P reduction and cost estimates.

6. The workshop group found the previous P fertili zer rates for citrus to be high because P fertilization on citrus typically only occu rs over the first few years after planting. This change significantly reduced the poten tial P reductions for the fertility BMP.

7. There were a few other minor changes made to P reduction ranges and typical values and the estimated costs of implementation as suggested by the workshop group. Most of these changes were associated with stor mwater retention and the fertility BMP.

8. An assessment table was also developed fo r the urban land use category because of this land use’s importance in any watershed BMP implementation programs.

The overall findings from this assessment are provided in Tabl e 1 while the detailed updated assessments for the primary agricultural and urba n land uses are provided in Attachment 1. As before, it is anticipated that the implementation of owner and typical cost share BMPs in the urban and agricultural sectors will still provide approximately a twenty five (25) percent reduction in phosphorus loads in to the tributary streams w ithin the Okeechobee basin.

Additional reductions could be achieved by a more aggressive BMP implementation program

within the basin. The reductions shown are for what are called a “typical” BMP implementation level under a moderately aggressi ve program that assumes a limited amount of cost share support will be availabl e for farmers and urban landowners.

Table 2 provides estimates of the tons of P reduction that might be expected across the Okeechobee basin, excluding the Upper Kissimm ee Chain of Lakes basins, based on BMP efficiencies presented in Attach ment 1 and the most recent (2 006) land use data provided by the

District. This table uses the same unit lo ading estimates as presented in Table 1.

It is recommended that the values in this report be updated peri odically as additional research

and field data come available.

Sincerely,

Del Bottcher, Ph.D., P.E.

Enclosures: Table1, Table 2, and Attachment 1Letter Report by SWET, Inc.3Letter Report by SWET, Inc.4Attachment 1 - Letter Report by SWET, Inc. A- 1 

### ATTACHMENT 1

Current condition assumptions, existing P loads, pote ntial P load reductions, and costs of implementation for the pr imary land uses withi n the Okeechobee

basin.

(Updated 8/8/06)

Table of Contents for BMP Assessment Tables

Citrus A- 2

Cow Calf Production – Im proved Pasture A- 3

Cow Calf Production – Unim proved Pasture A- 4 Cow Calf Production – Rangela nd/Woodland Pasture A- 5

Dairies A- 6 Field Crops - Hayland A- 7

Ornamentals A- 8

Pineland A- 9 Row Crop A-10

Sod / Turf Farm A-11 Sugarcane – Sandland A-12

Urban A-13Attachment 1 - Letter Report by SWET, Inc.A-2Attachment 1 - Letter Report by SWET, Inc.A-3Attachment 1 - Letter Report by SWET, Inc.A4Attachment 1 - Letter Report by SWET, Inc.A-5Attachment 1 - Letter Report by SWET, Inc.A-6Attachment 1 - Letter Report by SWET, Inc.A-7Attachment 1 - Letter Report by SWET, Inc.A-8Attachment 1 - Letter Report by SWET, Inc.A-9Attachment 1 - Letter Report by SWET, Inc.A-10Attachment 1 - Letter Report by SWET, Inc.A-11Attachment 1 - Letter Report by SWET, Inc.A-12Attachment 1 - Letter Report by SWET, Inc.A-13