United States
      Environmental Protection
      Agency
Total Maximum Daily Loads
THSDLs
   TMDL at a Glance
   Diamond Lake TMDLs- pH and
   Dissolved Oxygen
   (approved April 2007)
   www.deq.state.or.us/wq/tmdh/umpqua.htm
   Factors causing impairment
   Aesthetics, fishing, and water contact recreation
   designated uses impaired due to elevated pH levels
   and reduced dissolved oxygen levels from excessive
   algal blooms
   Sources contributing to impairment
   Introduction of the tui chub, an invasive fish species,
   resulting in the removal of native aquatic organisms
   that typically control algae growth
   Restoration options
   Tui chub removal and educational efforts to prevent
   introduction of invasive species
   Stakeholder involvement
   Umpqua National Forest, Oregon Department of Fish
   and Wildlife, Oregon Department of Environmental
   Quality, Partners for Umpqua Watersheds, Oregon
   Wildlife Heritage Foundation, Oregon Division of
   State Lands, Oregon Department of Agriculture,
   Douglas County, PacifiCorp, watershed residents,
   local businesses, and several other state and federal
   agencies
   Status of waternody
   Restoration of aquatic life designated use after removal
   of tui chub; anticipated attainment of other water
   quality standards with potential delisting by 2010
   Benefits to stakeholders
   Improved water quality, recreational opportunities
   (fishing, boating, and swimming), and lake aesthetics,
   as well as increased tourism
Restoring  Diamond  Lake's Water  Quality and Trout

Fishery Through Invasive  Species  Removal  and

Education

The introduction of rainbow trout to the naturally fishless Diamond Lake attracted
both wanted and unwanted visitors, resulting in significant changes to the health of the
      lake and lake-based recreational tourism. Fishing enthusiasts visiting Diamond
      Lake brought an invasive fish species, the tui chub, to use as live trout bait. (Live
      bait is illegal in Oregon.) Over time, the exploding tui chub population not only
      took its toll on the rainbow trout fishery, but also on the overall water quality of
      the lake. The tui chub fed on larger herbivorous zooplankton—the microscopic
      organisms in the lake responsible for controlling algae growth—throwing the
      lake's nutrient cycling processes off balance. As a result, Diamond Lake suffered
      from excessive growth of toxic algae blooms that increased pH levels  and reduced
      dissolved oxygen (DO) levels. Diamond Lake could no longer support its aquatic
      life designated use and was often closed for recreation during summer months due
      to potential health risks.
      The Oregon Department of Environmental Quality (ODEQ) initiated the
      development of a TMDL to help Diamond  Lake restore  its aquatic life designated
      use. The TMDL analysis predicted that removing the tui chub from Diamond Lake
      would restore the lake's nutrient cycling processes and support the aquatic life
      designated use. Based on the TMDL recommendations, multiple stakeholders from
      the federal, state, and local levels collaborated to develop and implement a plan
      to remove the tui chub and restore the trout fishery. The biology and chemistry of
      Diamond Lake have shown significant improvement due to the removal of the tui
      chub. As a result, Diamond Lake is now both fishable and swimmable. Currently,
      Diamond Lake is meeting Oregon's water quality standards and ODEQ expects
      to remove Diamond Lake from the state's list of impaired waters in the next
      assessment cycle in 2010.

      How are TMDLs at work in Diamond Lake?
      Through the technical analysis, the Diamond Lake pH and DO TMDL provided
      stakeholders with a clearer understanding  of the external and internal loads
      of nutrients affecting the levels of pH, DO, and algal blooms in the lake. The
      final TMDL report provided an explanation of how changes to the biological
      community found in Diamond Lake due to the tui chub population changed
      how efficiently the lake cycled nutrients, resulting in excessive algal blooms. The
      computer model tailored to Diamond Lake used in the TMDL analysis estimated
      the percentage of tui chub that stakeholders would need to remove from the
                                             What  is a total maximum daily load  (TMDL)?
                                             It is a study or analysis that calculates the maximum amount of a pollutant that a waterbody can receive and still meet
                                             water quality standards. The TMDL establishes a pollutant budget and then allocates portions of the overall budget to
                                             the pollutant's sources. For more information on TMDLs, visit EPA's website at www.epa.gov/owow/tmdl.

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             lake to improve the lake's nutrient cycling and restore
             water quality. In addition, the TMDL analysis revealed
             that changes in trout stocking densities would also be
             necessary to attain water quality standards.

             What  is the current status of Diamond Lake
             as a result of the TMDL process?
             In 2005, partners mechanically and chemically removed
             approximately 103,000 pounds of tui chub from Diamond
             Lake. Monitoring data collected in Diamond Lake after
             the removal of the tui chub demonstrate that the lake now
             supports its aquatic life designated use. To monitor the
             health of Diamond Lake after the removal of the tui chub,
             the Oregon Department of Fish and Wildlife (ODFW)
             assessed the lake in 2007 and compiled the 2008 Lake
             Conditions Index Report. This report uses metrics related
             to water chemistry and biology to measure changes in
             the lake's condition. The 2008 report states that Diamond
             Lake's pH levels are near or below the 8.5 water quality
             criteria value and DO levels meet the water quality
             criteria appropriate for Diamond Lake on most days. In
             addition, the 2008 report states that chlorophyll a values
             decreased from a high of 50 ug/L before the rotenone
             treatment to less than 10 ug/L (the numeric water quality
             criterion associated with aquatic weeds and algae) after
             treatment. Figure 1 illustrates the changes in chlorophyll
             a values in Diamond Lake before and after tui chub
             removal.
             Stocked trout health has also improved since the
             eradication of the tui chub, according to ODFW
             assessment data. Before the removal of the tui chub,
             stocked trout had a growth rate and a survival rate of
                          I     I    I    I
                     Feb     Apr      Jun
Oct
             Figure 1. Reduction in algal blooms, as represented by chlorophyll a, before
             and after chub removal.
nearly zero. During the summer of 2007, stocked trout
grew an average of two inches per month. ODFW states
that trout growth rates are now similar to the growth
rates observed in the 1970s and 1980s—the decades
known as the hey days for fishing in Diamond Lake.
Data from two years after tui chub eradication and
trout restocking have shown signs of water quality
improvements in Diamond Lake. Benthic organisms,
an important food source for mature trout, increased
from less than 25 pounds per acre (Ibs/ac) in 2004—2006
to 200.6 Ibs/ac in 2007 and 168 Ibs/ac in 2008. Before
treatment of Diamond Lake in 2006, the bio-volume of
cyanobacteria was 24,407 cells per milliliter (cells/ml), or
25.7 percent of the bio-volume. Two years after treatment
of the lake, the bio-volume of cyanobacteria decreased to
49 cells/ml or 4.9 percent of the bio-volume. ODEQ will
use this information and other required data inputs to
run the model used in the TMDL analysis to determine
how these decreases translate into annual cyanobacteria
biomass (i.e., kilograms/year) reductions—the numeric
target established in the TMDL. The pH of Diamond Lake
also decreased from 8.5 to less than 7.8 during this two
year period.

How did local stakeholders benefit from the
TMDL process?
Removal of the tui chub from Diamond Lake provided
the lake's natural nutrient cycling processes to regain
its balance. As a result, both water quality and the lake's
biological communities showed improvement. It is
anticipated that these improvements will lead to Diamond
Lake's removal from the state's list of impaired waters in
2010.
In addition to water quality benefits, the restoration of
Diamond Lake has benefitted stakeholders in several
ways. Additional benefits that followed the restoration of
Diamond Lake include:
O Decreased human health risks. Before treatment
   of Diamond Lake to remove the tui chub, state
   officials closed the lake for recreation during summer
   months when the toxic blue-green  algae dominated
   the lake. Blue-green algae blooms produce toxins
   that are harmful to humans and animals. After
   implementation, blue-green algae went from the
   dominant algae type in Diamond Lake to only a small
   percentage of the algal community.
O Revived tourism to boost local economy. Diamond
   Lake recreational enthusiasts contribute approximately
   $3.5 million to the local economy each year. Restoring
   water quality and aquatic communities have helped to
   also restore Diamond Lake's reputation as a favorite
   destination for trout anglers. According to ODFW,
Diamond Lake-2

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   there were 72,085 angler trips in 2007. These trips
   generated an estimated $3.76 million in sales and
   $2.57 million in labor income in the area (based on the
   2006 value of the dollar). The Diamond Lake Resort,
   the third largest employer in the area, had a staff of
   80 when tourism was suffering most and has since
   increased the staff by over 60 percent due to the boost
   in lake-based tourism.
O  Improved aesthetics. Significant reductions in
   nuisance algae occurred and the lake increased
   from a visible depth of 10 feet to almost 50 feet after
   implementation.
O  Increased educational awareness to prevent spread
   of invasive species.
   It is illegal to use live bait for fishing anywhere in
   Oregon. The educational effort for Diamond Lake
   reminds visitors of that law through educational
   brochures and signage around the lake. In addition,
   partners conducted a boater survey to better
   understand boaters' habits and perceptions relating
   to the spread of invasive species. Educational efforts
   remind boaters and recreational enthusiasts of the
   simple steps they can take, such as washing boats and
   fishing equipment, to avoid giving aquatic hitchhikers
   a free ride to Diamond Lake.
"Anyone working in recreation does it for the
satisfaction, not for the money, but it is our
livelihood. When your lake has a problem, you
get involved to find a solution. Getting involved
answered a lot of questions for us about the area.
We found a solution  that had a huge ripple effect
both on the lake's ecosystem and on our local
economy."
                        —Rick Rockholts, Manager
                             Diamond Lake Resort
                           For more information on the Diamond Lake TMDL, contact
                         Paul Heberling, Oregon Department of Environmental Quality
                            heberling.paul@deq.state.or.us, (541) 440-3338 x224
           For more information on the Oregon TMDL Program, visit www.deq.state.or.us/WQ/TMDLs/TMDLs.htm
                                           &ER&
                                          December 2009
                                       EPA841-F-09-002T

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