Ecological and Beneficial Use Assessment of Farmington Bay Wetlands: Assessment and Site-Specific Nutrient Criteria Methods Development Phase I
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Resource ID
8369
Resource Type
Document
UGS Program
Wetlands
Title
Ecological and Beneficial Use Assessment of Farmington Bay Wetlands:
Assessment and Site-Specific Nutrient Criteria Methods Development Phase I
Author
Theron G. Miller, Ph.D. and Heidi M. Hoven, Ph.D.
Date
April 10 2007
Country
USA
Keywords
monitoring, assessment, EPA, wetland, core element, Farmington Bay, impounded, waterfowl, water quality, invertebrate, public shooting grounds, great salt lake, nutrient, water quality standards, UDWQ, Utah Division of Water Quality, The Institute for Watershed Science
Document Type
Report
Original Filename
WTLND0060.pdf
Geotechnical Database
Not Included
Abstract / Description
Executive Summary
Background and Purpose of Study
There has been a growing concern by waterfowl managers, scientists and citizen groups that the
nutrient load from wastewater discharges along the Wasatch front may be exceeding the
assimilatory capacity of the wetland and Farmington Bay ecosystems. Concurrent with this
growing concern, EPA has been encouraging states to develop methods for assessing wetland
condition. Utah DWQ applied for and received three Wetlands Protection Grants starting with
the 2004 field season. The primary objective of this study is to develop assessment methods that
will be used to perform §305(b)/303(d) assessments. This process will include establishing sitespecific
criteria for phosphorus. Total nitrogen never exceeded Utah’s narrative standard of 5 mg
L-1 and it was indeed often below instrument detection limits of 0.05 mg L-1. Therefore, although
the wetlands and Farmington Bay were nearly always nitrogen limited, it is unlikely that
treatment options would reduce ambient nitrogen concentrations and therefore change ecological
conditions of the Bay or wetlands. Additional evidence for this conclusion is the frequent
dominance of nitrogen-fixing Cyanobacteria throughout the Bay and wetlands, which would
negate any nitrogen removal in wastewater treatment systems.
This effort represents one of the first attempts by any of the states to establish water quality
standards and methods for wetlands 303(d) assessment. This is primarily because wetlands
assessment methods development is in its infancy and there is a dearth of data describing the
relationship between nutrient gradients and biological responses in wetlands, particularly Great
Salt Lake wetlands. Therefore, our goals are twofold: 1) test existing parameters outlined in
EPA’s various assessment modules and other potentially useful parameters for their utility in
assessing Great Salt Lake wetlands; and 2) Develop metrics and ultimately an Index of
Biological Integrity (IBI) that will identify thresholds of significant change (impairment) that can
be attributed to nutrients. These thresholds will then be used to set a site-specific water quality
standard for phosphorus and simultaneously used to determine beneficial use support status.
The initial wetlands study design focused on measuring nutrient attenuation along a longitudinal
gradient established by water passing through successive impoundments or at increasing
distances across the mudflats from POTW discharges. We identified reference (least impacted)
as well as target (nutrient enriched) sampling sites. Particular biotic parameters that we focused
on include: macrophytes (percent cover, stem height, species composition, tissue nutrient
concentrations and ratios, above ground biomass) phytoplankton and periphyton community
structure; macroinvertebrate community composition and shorebird nesting success and forage
preference studies. Abiotic factors in the water include total phosphorus (P), nitrate-nitrite (N),
ammonia, metal concentrations, pH, electrical conductance (EC), dissolved oxygen (DO) and
temperature. Sediment nutrient concentrations, organic carbon, pH and EC were also measured.
Several reports were prepared by individual contractors (see Appendices). This report
summarizes and assimilates the wetland reports and data and includes additional analyses
pertaining to wetland function and nutrient dynamics. Potential metrics are reviewed and
additional data gaps are identified that will increase the accuracy of the wetland assessment.
Marker lat / long: 40.927876, -112.014988 (WGS84)