Medicine Lake
Excess Nutrients
TMDL project:
Water Quality
Standards
Steering Committee Meeting #1
November 18th, 2008
Minnesota Pollution Control Agency
Minnesota Pollution Control Agency
Water Quality Standards
Water quality standards –
the fundamental benchmarks by which
the quality of surface waters is measured
(Minn. Rules Chapter 7050 and 7052 govern program)
http://www.pca.state.mn.us/water/standards/index.html
Minnesota Pollution Control Agency
Water Quality Standards
Water quality standards consist of 3 major
components:
1. Beneficial use
classifications for
waterbodies
2. Numeric and narrative
criteria that protect
those beneficial uses
3. Nondegradation requirements
to provide extra protection to
high quality waters
Minnesota Pollution Control Agency
1. Beneficial Use
Classifications
Use Class Beneficial Use
Class 1
Drinking Water
Class 2
2A
2Bd
2B
2C
2D
Aquatic life and recreation
Cold water fisheries, trout waters
Cool and warm water fisheries, drinking water
Cool and warm water fisheries
Indigenous fish and associated aquatic community
Wetlands
Class 3
Industrial uses and cooling
Class 4A
Agriculture and wildlife uses
Class 5
Aesthetics and navigation
Class 6
Other uses
Class 7
Limited resource value waters
Minnesota Pollution Control Agency
1. Beneficial Use
Classifications
Protection of aquatic life:
healthy, diverse, and
successfully reproducing
populations of aquatic
organisms (including fish and
invertebrates) are maintained
Protection of recreation:
conditions suitable for
swimming and other forms
of water recreation are
maintained for all surface
waters (except wetlands and
Class 7 waters)
Minnesota Pollution Control Agency
2. Numeric Water Quality
Standards
„Sets a specific concentration for a certain
pollutant in water that will allow
maintenance of beneficial uses
„All use classifications have numeric
standards associated with them
(except Class 6 – other uses)
„Ideally, if the numeric standard is not
exceeded, the beneficial use will be
protected
Minnesota Pollution Control Agency
2. Narrative Standards
„prohibit unacceptable
conditions in/on water
„ floating solids
„ scum
„ visible oil film
„ nuisance algal blooms
„are sometimes called “free forms”
„protect aesthetics
Minnesota Pollution Control Agency
Lake Nutrient Criteria
Development
„ Considers regional patterns & distributions;
„ Varying uses of lakes & differences among
deep & shallow lakes;
„ Consider fishery (aquatic life) requirements;
„ Shallow lakes – emphasis on plant communities
relative to P, chl-a, & Secchi;
„ Use of sediment cores to re-affirm regional
patterns & estimate background;
„ Accounts for lake user perceptions;
Minnesota Pollution Control Agency
„ Due to regional
diversity in lake
and watershed
characteristics
one single TP
value could not
be adopted for
the state
Minnesota Pollution Control Agency
Trophic Status of Lakes
„ the typical trophic status range of
reference lake data represents a starting
point for establishing criteria
Trohpic Status = overall health or level of productivity of
the lake
Reference Lake = representative lake in minimally
impacted watershed
Minnesota Pollution Control Agency
Carlson Trophic Status (TSI)
Minnesota Pollution Control Agency
Natural Background Conditions
and Regional Patterns
„ “55 Lakes Study” conducted in Minnesota
included lakes from the major ecoregions
„ Surface and deep cores were taken in all lakes
„ Core-sections corresponded to circa 1750,
1800, 1970, and 1993
„ Diatom reconstructions of pH, chloride, color,
acid neutralizing capacity, total phosphorus,
trace metals and organic contaminants were
conducted
Minnesota Pollution Control Agency
User Perceptions
„ Defining the relationship between user
expectations and lake water quality
measurements important
„ Methodology involves the use of an observer
survey and water quality data from the
ecoregion data set and Citizen Lake-Monitoring
Program.
„ Cross-tabulating water quality measurements
against observer survey categories provides a
basis for calibrating nuisance criteria.
Minnesota Pollution Control Agency
User Perceptions Data
Minnesota Lake Water Quality Assessment
Report: Developing Nutrient Criteria (Sept. 2005)
http://www.pca.state.mn.us/water/lakequality.html
Minnesota’s Lake Eutrophication Criteria.
Minnesota Pollution Control Agency
Ecoregion
(classification)
TP
Secchi
ppb
meters
12
20
30
3
6
9
4.8
2.5
2.0
20
40
60
6
14
20
2.5
1.4
1.0
WCP & NGP – Aquatic Rec. Use
(Class 2B)
65
22
0.9
WCP & NGP – Aquatic Rec. Use
(Class 2b) Shallow lakes
90
30
0.7
NLF – Lake trout (Class 2A)
NLF – Stream trout (Class 2A)
NLF – Aquatic Rec. Use (Class 2B)
CHF – Stream trout (Class 2a)
CHF – Aquatic Rec. Use (Class 2b)
CHF – Aquatic Rec. Use (Class 2b)
Shallow lakes
ppb
Chl-a
Minnesota Pollution Control Agency
Photo by: Terrie Christian—President, AMLAC