Project Title: Analysis of Historical Water-Quality Data

Project Start Date: 2001 Project End Date: 2005

Web Sites: data available at SOFIA

Location (Subregions, Counties, Park or Refuge): Everglades National Park (ENP), Big Cypress National Preserve (BCNP), Loxahatchee National Wildlife Refuge (LNWR), Biscayne Bay National Park (BBNP)

Funding Source: USGS's Greater Everglades Science Initiative (PBS); CESI in 2001.

Principal Investigator(s): Benjamin McPherson

Project Personnel: Ronald Miller

Supporting Organizations: NPS; USFWS

Associated / Linked Projects:

Overview & Objective(s): The project provides a review and analysis of historical water-quality data in BCNP and ENP and other DOI lands in south Florida. This information will help establish water-quality standards and baseline conditions in the parks, and will help evaluate the potential effects of CERP on water quality. Objectives include: (1) assemble water quality data; (2) review and edit the data and provide a working data base; (3) analyze and evaluate the data and prepare interpretative reports on baseline water-quality conditions and trends in BCNP, ENP and other DOI lands, so as to provide a basis for evaluating how CERP might affect water quality in these park and refuge lands.

Status: Active; on-going

Recent & Planned Products: Major tasks and products include: (1) a reviewed and edited database of historical water-quality constituents in BCNP, ENP and Loxahatchee National Wildlife Refuge (LNWR). This task has been completed and the databases provided to NPS and FWS and made available on the SOFIA web site; (2) an interpretative report on water quality for the period of record for BCNP and ENP. A draft report has been completed, reviewed, and submitted for publication as USGS Water Resources Report and as a Fact Sheet. Results from the report were presented at the April 2003 GEER conference as a poster and abstract; (3) a second interpretative report is planned in 2004 that summarizes baseline water-quality conditions and trends in LNWR; (4) a data base of historical water quality and a third report are planned for Biscayne Bay National Park (BBNP) in 2005.

Relevance to Greater Everglades Restoration Information Needs: For Everglades restoration it is essential to know historic baseline water-quality conditions, how water quality may have changed, and what are the current conditions. The project provides information to assess these aspects of water quality, including seasonal and long-term trends, and potential sources of water quality problems in the parks and refuge.

Key Findings: Major results from the analysis of the historic water-quality data include:

• Some of the long-term trends in sulfate and total phosphorus were likely attributable to high percentages of less-than and zero values and to changes in reporting levels over the period of record, rather than to real environmental changes.
• High spikes in nutrient concentrations were evident during dry periods, and attributable to increased canal inflows of water that is nutrient-rich relative to marsh inflows, to increased nutrient releases from breakdown of organic bottom sediment, or to increased build-up of nutrient waste from concentrations of aquatic biota and wildlife in remaining ponds.
• Concentrations of total phosphorus generally are higher in BICY (median values, 1991-2000, were mostly above 0.015 mg/L) than in EVER (median values, 1991-2000, below 0.01 mg/L), probably because of higher phosphorus in natural sources such as shallow soils, rocks, and ground water in the Big Cypress region than in the Everglades region.
• Concentrations of chloride and sulfate, on the other hand, are higher in EVER (median values in Shark River Slough, 1991-2000, mostly above 2 mg/L sulfate and 50 mg/L chloride), than in BICY (median values, 1991-2000, less than 1 mg/L sulfate and at most sites less than 20 mg/L chloride), probably because of the canal transport system that conveys more water from agricultural sources into EVER than into BICY.
• Concentrations of pesticides rarely exceeded aquatic life criteria in BICY and EVER. Atrazine was the only pesticide that exceeded the criteria (in 2 out of 304 samples). The pesticides p, p'-DDE, lindane, and heptachlor expoxide exceeded criteria in canal bed sediments in 16, 2, and 1 percent of the samples, respectively.