• 1. Temperature TMDLs
    1. Temperature TMDLs

    I'm Salmo, a kokanee salmon. I was asked by the Lake Roosevelt Forum to tell you a little about Total Maximum Daily Load (TMDL) standards for temperature in Lake Roosevelt.

    TMDLs are part of setting water quality standards and implementing water improvement plans. These standards and plans let humans, fish and other species benefit from our precious rivers, lakes and streams. When I say benefit I mean using our waterways for things like drinking water, irrigation, recreation, power generation, flood control, and quality habitats for fish like me.

    With so many beneficial uses, it can be hard to balance everyone's needs and wants. To learn more about TMDLs, click on the TMDL Links icon below.

  • 2. Importance of Water Temperature
    2. Importance of Water Temperature

    Cool water is important to my health, and the health of other salmon and trout. We're all lumped into a category of fish biologists call salmonids. We're cold-blooded animals or ectothermic, which means our body temperature depends on our surroundings... and we like it pretty cold. If the water temperature gets too warm, it can harm us.

    Our lives are also closely tied to water temperatures. The right temperature is kind of like an alarm clock for us, signaling us when it's time to do something important. For example, many of us start spawning in the fall when water temperatures drop to just the right temperatures. And, rising springtime water temperatures may serve as a wake up call for us to migrate.

  • 3. Dam Locked
    3. Dam Locked

    In Lake Roosevelt, we're "dam-locked." That means that Grand Coulee Dam (and Chief Joseph Dam just below Grand Coulee) block us from going upstream. So our life cycle is completed within Lake Roosevelt and its tributaries.

    Before the dam was built, salmon species like steelhead and chinook migrated all the way to the ocean and back from this area. That's over 1,200 miles, talk about a journey!!!

    Salmon that live part of their life in the ocean are called anadromous fish. Even though I'm related to them, I'm called a resident fish because I stay within rivers, lakes and streams.

    Whether an anadromous or resident fish, scientists agree that water temperature is a very important habitat component for us. Our health depends on it !!!

  • 4. TMDLs and Water Temperature
    4. TMDLs and Water Temperature

    When thinking about water temperature in Lake Roosevelt, there are really two stories to tell. The first is what types of temperatures I and other species need and like. The second is how the temperatures up here affect the needs of my kin downstream. When setting TMDLs for water temperature, scientists and managers account for both.

  • 5. Species and Temperature
    5. Species and Temperature

    There are over 30 fish species in Lake Roosevelt. When considering habitat conditions, managers tend to focus on the needs of kokanee and redband/rainbow Trout. These fish are native to the area, which means we've been here for centuries.

    The temperatures we prefer vary between 5 and 17º Celsius (41-62.6ºF) for kokanee, and 12 to 18º Celsius (53.6-64.4ºF) for rainbow trout. Thankfully, temperatures in the lake generally fall in this range. The exception is the summer months. Because the lake is flat and not flowing rapidly, temperatures (particularly at the surface) can heat up beyond what's good for us. In August, the average surface temperature in Lake Roosevelt is about 21º Celsius (69.8ºF).

    To adjust for these conditions, we can swim deeper than we normally would. For those of us looking to meet our food and oxygen needs, managers and scientists are monitoring how this adjustment affects our health.

  • 6. Warm Temperatures
    6. Warm Temperatures

    Did you know that warm water is the most common reason why water bodies don't meet Water Quality Standards throughout the Northwest?

    Of the water bodies listed as "impaired" in Washington, Oregon, Idaho and Alaska, 29% had this designation because of warm water temperatures. These waters are placed on the 303(d) list and trigger the TMDL process. To learn about what 303(d) listing means and the TMDL process, click on the TMDL Links icon below.

    Of the 600 waters on the 303 (d) list in Washington, about 300 were listed for temperature. The length of the Columbia from Canada to the ocean is on this list.

  • 7. TMDL Criteria
    7. TMDL Criteria

    Because of this listing, a temperature TMDL is being developed. EPA was asked by state and tribal governments to take the lead in coordinating development of temperature TMDLs for the Columbia and Snake Rivers. The main reasons for this are that there are federally owned hydroelectric projects on the Columbia, and there are inter-state and tribal issues involved.

    To understand how EPA is developing the temperature TMDL, you need to think about the length of the Columbia from the Canadian border to the ocean.

    The key concept is that the water from Canada to the ocean naturally warms up. This is particularly true in the summer when it's hot. So for the water downstream to be cooler, Lake Roosevelt's water needs to be the coolest of the cool. Technically, that's why Ecology has set a temperature criteria of 16º Celsius (61ºF) in Lake Roosevelt. In the lower Columbia, it's 20º Celsius (68ºF).

    The graphic shows the temperature criteria created for three reaches of the Columbia. This criteria uses "natural conditions" as a reference point. These conditions reflect environmental conditions before human changes. The criteria sets an allowable amount that human activities can warm the river above natural conditions.

  • 8. Causes of Increased Temperatures
    8. Causes of Increased Temperatures

    As part of the TMDL process scientists studied the Columbia and Snake system to understand what causes increased temperatures. They analyzed everything from global warming to paper mills.

    They found that the biggest influence on temperature is hydroelectric reservoirs. Scientists estimate that the reservoir (Lake Roosevelt) behind Grand Coulee can increase water temperature in the Columbia River by as much as 6 degrees Celsius above natural conditions, the most of any of the facilities. Hydroelectric facilities are grouped into the category of non-point source pollution. Other examples of non-point source pollution are erosion and removal of shading vegetation next to waterways.

    Another source of pollution is called point source. These are discharges directly into the water, like waste water treatment plants and paper mills. There are 202 point source discharges in this part of the Columbia, but as the graphic shows, the effect of all these point sources combined is minor compared to the effect of reservoirs behind hydroelectric projects.

  • 9. Cooling the Water
    9. Cooling the Water

    There are challenges to cooling the water in Lake Roosevelt and downstream. If you read about the operations of Grand Coulee dam, you'll learn about the many factors that the US Bureau of Reclamation and other agencies consider when deciding how much water should be in the lake, how fast it moves through and how much goes downstream, all of which can affect temperature. These operational decisions are done to support other beneficial uses of Lake Roosevelt such as flood control, power generation, fishery needs, irrigation and recreation.

    So scientists are studying ways to cool the waters and protect other beneficial uses.

  • 10. Status of the Temperature TMDL
    10. Status of the Temperature TMDL

    So here's the status of the temperature TMDL. The EPA, working with a whole school of groups (Washington, Oregon, Idaho, the Colville Confederated Tribes, the Spokane Tribe of Indians and other federal and local agencies and interested parties) has completed a DRAFT TMDL for the Columbia and Snake Rivers. The TMDL mathematically allocates how much the temperature needs to be reduced at each source to help meet water quality standards.

    Because of the challenges managers and scientists face when trying to reduce temperature, EPA has started to develop (with everyone who is interested) a DRAFT Summary Implementation Strategy. EPA is planning to develop the TMDLs and the Implementation Strategy iteratively, which means they will work on them together and modify each as they learn new information.

  • 11. Summary Implementation Strategy
    11. Summary Implementation Strategy

    I'm happy to tell you that the DRAFT Summary Implementation Strategy includes an initial list of actions for improving temperature at the dams. Many of these actions are studies to help clarify issues, determine the feasibility of structural improvements, address environmental impacts, and quantify the benefits of improvement measures.

    For instance, they are studying if water at a lower depth can be released from Grand Coulee Dam. Remember, the water is cooler down there. But whether it'll make a difference is a complicated question. For instance, is the temperature difference and amount that can be sent downstream enough to make a difference? As importantly, if cooler water is taken downstream, will Lake Roosevelt heat up and cause a problem for me and my friends?
    Photo shows the confluence of Snake & Columbia rivers.

  • 12. TMDL Studies
    12. TMDL Studies

    Once completed, the studies should tell us whether the level of improvement at the dams, called for by the TMDL, can be reached.

    I should probably mention that the Clean Water Act also says that if a beneficial use is not attained due to the presence of dams then adjusting the water quality standards may be an option. But that is the case only if it's not feasible to restore the river to its original condition, or to operate the dam system in a way that would allow for the beneficial use.

    To revisit the standards, a Use Attainability Analysis (UAA) would be initiated. A UAA is generally done when the standard can not be met all the time. The analysis will help determine if species such as myself can have our needs met when this situation occurs and, if not, what to do.

  • More to Come
    More to Come

    My fish sense is that you'll be hearing a lot more about temperature in Lake Roosevelt and on the whole Columbia and Snake Rivers in the years to come.

    Like I said, there are no simple answers. But I'm confident that by continuing to work together improvements can be made that help Lake Roosevelt and the rest of the Columbia.

    To learn more about temperature TMDLs, click on the TMDL Links icon below.