On January 22, 2026, the final court proceedings occurred in litigation by Klamath Water Users Association challenging the Oregon Department of Environmental Quality’s (ODEQ) 2019 total maximum daily load (TMDL) for water temperature in the Klamath and Lower Lost River basins in Oregon.
KWUA led a coalition that included Klamath Drainage District, Van Brimmer Ditch Company, Ady District Improvement Company, and Tulelake Irrigation District in the case, which was filed because of concerns that the Temperature TMDL could lead to major capital and operational costs being incurred by KWUA members, as well as threatened negative impacts to irrigation water supply.
The Marion County Circuit Court agreed with the petitioners, finding the temperature TMDL to be unlawful, and on October 8, 2025, the Oregon Court of Appeals affirmed this ruling.
At the January 22, 2026 proceeding back in Marion County Supreme Court, all parties confirmed that the Temperature TMDL is of no effect.
The lawsuit by KWUA and KWUA members was one of a total of four cases that challenged two distinct TMDLs. The Court of Appeals’ rulings do mean that water management agencies can be assigned responsibilities regarding implementation in future TMDLs, but in the meantime, the Temperature TMDL, the target of KWUA’s case, is not in effect as a result of the litigation.
Background
TMDLs are driven by the federal Clean Water Act (CWA), which is largely administered by Oregon and many other states within their borders. Section 303 (c) of the CWA requires that states adopt water quality standards for the protection of beneficial uses of water. (For example, a water quality standard might be: 10 parts per billion of copper, for the protection of aquatic life.)
Section 303(d) of the CWA requires that states periodically publish lists of waters or water segments where their water quality standards are not being achieved. Section 303(d) of the CWA requires that the states prepare TMDLs for the waterbodies or segments on this “impaired waters” list.
A TMDL is a scientific evaluation of the total amount of loading of a given pollutant that a water body can hold and still meet water quality standards. (For a temperature TMDL, heat or heating is the “pollutant”). The TMDL also allocates this total loading among sources.
The CWA does not require implementation or enforcement of TMDL allocations (although they are effectively self-implementing for those sources who must have CWA point source discharge permits which are renewed periodically). However, Oregon state law requires that ODEQ and the Oregon Department of Agriculture prepare water quality management plans (WQMPs) for the implementation of the federally required TMDLs.
The Litigation
In January, 2019, ODEQ adopted a TMDL and a WQMP plan for nutrients. Langell Valley (LVID) and Horsefly (HID) Irrigation Districts filed legal challenges to this TMDL.
In December, 2019, ODEQ adopted the Temperature TMDL and WQMP. This TMDL was challenged by KWUA and members identified above and, in separate lawsuits, also by PacifiCorp and LVID and HID. PacifiCorp’s challenge was driven by concerns over the impacts of the TMDL on PacifiCorp’s operation of Keno Dam, which was at that time still owned and operated by PacifiCorp.
These three petitioners made several arguments. On March 18, 2022, the Circuit Court issued its decision in the cases. The Circuit Court agreed that the Temperature TMDL was invalid because of its use of California water quality standards for the Klamath River in California for calculations of maximum allocations.
The Circuit Court also agreed with well-developed arguments by LVID and HID that the Temperature TMDL and the Nutrient TMDL WQMPs both improperly assigned implementation planning responsibilities to water management agencies, such as irrigation districts. The TMDL characterized these types of agencies as “responsible parties,” a term that is not identified in Oregon law as being among those who can have implementation responsibility. Also, LVID and HID asserted that irrigation districts’ statutory authorities are limited and do not include the kind of TMDL implementation activities that were contemplated in the two TMDL WQMPs. In its Temperature TMDL lawsuit, the KWUA group asserted these same arguments.
ODEQ appealed. In October 2025, the Oregon Court of Appeals upheld the Circuit Court’s ruling that the Temperature TMDL was unlawful. However, the Court of Appeals ruled that a TMDL can properly assign implementation responsibilities to water management agencies.
Now What?
The Temperature TMDL is of no effect. Although KWUA achieved its goal in this case, the broader public interest context is unfortunate. States’ CWA obligation to prepare TMDLs is a major burden. States frequently are targets of citizen lawsuits by environmental organizations who seek court order requiring that the state complete a given TMDL, or a group of TMDLs, by a specific date. These cases are routinely successful, and the plaintiff organizations recover attorneys’ fees from the targeted state.
The Temperature TMDL was prepared under a court-imposed deadline in a citizen suit. KWUA believes that ODEQ could have prepared a more defensible product, but it did not have sufficient time to do so with its limited resources. As a result, the citizen plaintiffs received money, and, since the Temperature TMDL has been invalidated, nothing was actually accomplished.
The nutrient TMDL survived, but LVID and HID’s litigation challenging that TMDL is still viable. Because of its ruling on responsible parties, the Circuit Court did not, in its 2022 decision, need to reach certain arguments raised by LVID and HID. With the Court of Appeals now having ruled that LVID and HID can properly be assigned implementation responsibilities, the Circuit Court will need to address other issues that LVID and HID raised in their Nutrient TMDL lawsuit that concern the propriety of specific elements of the TMDL.
The Court of Appeals’ “responsible parties” ruling means that irrigation districts and other water management agencies can be assigned responsibilities under future TMDLs, at least for developing implementation plans for their areas. Several years ago,
KWUA compiled plans of this sort prepared by districts in other parts of the state, and those plans will be available for members.
In the Klamath Basin, excess nutrient concentrations are a problem. However, like LVID and HID, KWUA did and still does have concerns about specific elements of the Nutrient TMDL.
KWUA, in partnership with ODEQ and many other parties, has undertaken initiatives to address nutrient and other water quality concerns on a regional basis. KWUA believes these kinds of solutions are both more reasonable and more effective than a “command and control” mindset that emphasizes regulation for its own sake.
