State of Green Bay: Impairments from Total Phosphorus and Total Suspended Solids

1
State of Green Bay Impairments from Total
Phosphorus and Total Suspended Solids

Victoria A. Harris UW Sea Grant Institute FWWA
Conference March 14, 2007
2
State of Green Bay

• Largest of lakes bays at 120 mi length, but much
  shallower, warmer and eutrophic
• Flushing time
• Lake Michigan 99 yrs.
• Green Bay lt 1 yr.
• Fox-Wolf River basin contributes the largest
  proportion of pollutants to the lake
• 26 of TP tributary load
• 57 of PCB tributary load
• 44 of total Hg tributary load
• Water quality status - poor grading to good

Good
Fair
Poor Declining
ERSC, UW-Madison
3
Green Bays Trophic Gradient

• Hypereutrophic conditions in the southern bay
  (AOC), meso-trophic conditions in the middle bay,
  oligotrophic conditions in the northern bay,
  similar to the lake
• Trophic Indicators in lower Bay
• TP Status poor
• TSS Status poor
• Chlorophyll Status poor
• Water clarity Status poor
• NH3 water column meets standards but toxicity
  in sediments

Lower Green Bay AOC
Fox River
ERSC, UW-Madison
4
GBMSDSampling Stations
5
Status - Poor Trend - deteriorating

• Southern Green Bay AOC exceeds the RAP/STAC
  target by 360
• Average TP concentrations increased by 22.5 in
  lower Green Bay post zebra mussels, while Fox R.
  loads remained about same
• 34 - 49 of phosphorus increase attributable to
  lower lake levels

6
Lower Green Bay Chlorophyll a (Algae)

• Current chl a concentrations are above the target
  levels of RAP and STAC
• Chl a concentrations have significantly decreased
  since zebra mussels were
• introduced into Green Bay (32.2 in zone 1
  49.9 in zone 3)

7
Lower Green Bay Total Suspended Solids

• 12.7 decrease in average TSS post-zebra mussel
  invasion in zone 1

8
Lower Green Bay Secchi Depth (Water Clarity)
9
State of the Bay Indicators

• Trophic state (TP, TSS, NH3, chlorophyll, water
  clarity)
• Chemicals of concern (PCBs, Hg and other toxins)
• Drinking water
• Fish consumption advisories
• Fish populations
• Benthic Macroinvertebrates
• Aquatic nuisance species
• Waterfowl use
• Coastal wetlands
• Beach closures
• Recreational Use (boat registrations and fishing
  licenses)
• Land Use

10
Great Lakes Water Quality Agreement
-

• Restore chemical, physical and biological
  integrity of Great Lakes ecosystem
• Identify Areas of Concern
• geographic areas where Great Lakes beneficial
  uses are prohibited or impaired
• Enlist States and Provinces to prepare and
  implement Remedial Action Plans

11
Impaired Uses due to TP and TSS in Lower Green Bay

• Nuisance and harmful algal blooms (blue-green
  algae)
• Poor aesthetics, closed beaches
• Lost tourism, lower property values
• Taste and odor problems for drinking water
• DO fluctuations, hypolimnetic anoxia
• Ammonia toxicity in sediments
• Poor water clarity, loss of SAV
• Altered food webs, degraded benthic, fish and
  wildlife communities

SAV Loss Water Celery
12
Waterfowl

• Historically, Green Bay was an important
  migratory stopover
• Half million ducks harvested per year in market
  hunting era
• 1997 maximum daily count on lower Green Bay was
  40,000 diving ducks

13

• Number of ducks, particularly diving ducks,
  seriously declined from the 1960s through the
  1980s
• A 1977 US FWS Estuary Study concluded the bay had
  become food limited for migrating waterfowl due
  to declining benthic invertebrate populations and
  the loss of submerged aquatic vegetation

14
Suspended solids and algae limit sight-feeding
predator fish
15
Before 1985, 600,000 cubic yards dredged every
year to maintain navigation channelIn recent
years, only 85,000 to 100,000 cubic yards of
sediment is dredged every year
Renard Island CDF
East River empties into port turning basin
16
 
 
17
Total phosphorus loads for the Fox-Wolf basin
including Duck Creek
Data and graph from TMDL draft report, 2005
18
RAP Recommendation Reduce total phosphorus load
from Fox River to Green Bay by 50
Fox River
Apple Creek
19
(No Transcript)
20
RAP Recommendation Reduce total suspended
solids load from Fox River to Green Bay by 50
Agricultural land erosion
Construction site erosion
21
State of The Bay Acknowledgments

• RAP Science and Technical Advisory Committee
• Green Bay Metropolitan Sewerage District
• WDNR
• U.S. Fish and Wildlife Service
• U.S. EPA
• UW Aquatic Sciences Center
• UW Environmental Remote Sensing Center
• Bay-Lake Regional Planning Commission