Notable Water Law Cases (2000-2025)
Clean Water Act
Supreme Court ruled that the Clean Water Act does not authorize EPA to impose "end-result" requirements in discharge permits, limiting EPA's authority to hold permittees responsible for water quality in receiving waters without specifying concrete compliance steps.
📍 California | Supreme Court Decision
Interstate Dispute
Supreme Court ruled 5-4 that the federal government must consent to any settlement between states over the Rio Grande Compact. The decision strengthened federal authority in interstate water negotiations and has implications for Colorado River negotiations.
📍 Texas, New Mexico, Colorado | Rio Grande Compact
Tribal Water Rights
Supreme Court held that the 1868 treaty did not require the United States to take affirmative steps to secure water rights for the Navajo Nation, despite the tribe's reservation along the Colorado River.
📍 Arizona, Colorado River | Supreme Court Decision
Interstate Dispute - Groundwater
Landmark Supreme Court decision extending equitable apportionment doctrine to groundwater for the first time. The Court ruled that Mississippi does not have absolute ownership of groundwater in the Middle Claiborne Aquifer; instead, the water is subject to equitable apportionment between states.
📍 Mississippi, Tennessee | Middle Claiborne Aquifer
Interstate Dispute
Supreme Court denied Florida's request for water allocation caps on Georgia's usage of the Apalachicola-Chattahoochee-Flint River Basin. Court found Florida failed to provide clear and convincing evidence that Georgia's water use caused the collapse of Florida's oyster fisheries.
📍 Florida, Georgia | ACF River Basin
Interstate Compact
Supreme Court resolved disputes over the Yellowstone River Compact, specifically regarding Wyoming's change from flood to drip irrigation technology. The Court held that technological changes not expressly forbidden by the compact were permissible.
📍 Montana, Wyoming, North Dakota | Yellowstone River
Federal Reserved Rights
Colorado water courts recognized a unique groundwater right based on federal law for Great Sand Dunes National Park, following an uncontested trial, establishing important precedent for federal reserved water rights in national parks.
📍 Colorado | Federal Reserved Rights
Federal Reserved Rights
Groundbreaking settlement agreement recognized federal reserved water right for Black Canyon of the Gunnison National Park after decades of litigation, balancing interests of the United States with state, irrigation, environmental, and other stakeholders.
📍 Colorado | Multi-party Settlement
Interstate Dispute
Tribal Water Rights
Supreme Court approved settlement regarding Fort Mojave and Colorado River Indian Reservations and ruled in favor of Quechan Tribe's claims. The Court adjusted specified water amounts for several parties to the longstanding Colorado River dispute that began in 1952.
📍 Arizona, California, Nevada | Colorado River
Federal Reserved Rights
Settlement recognized instream flow rights for the Forest Service on every major stream in the Rio Grande River Basin, representing a significant success in protecting federal reserved water rights for environmental purposes.
📍 New Mexico, Colorado | Rio Grande Basin
State Adjudication
Washington State initiated one of the first adjudications to include both surface water and groundwater, requiring domestic well owners to appear in court to protect their groundwater rights. This represents a major shift in groundwater management.
📍 Washington | Groundwater & Surface Water
Federal Reserved Rights
One of the largest water adjudications, covering 87% of Idaho's water. Federal courts addressed virtually every major reserved right claimed by Forest Service, National Park Service, Fish & Wildlife Service, BLM, and Bureau of Reclamation. Awarded reserved rights for Hells Canyon NRA, six Idaho Wild and Scenic Rivers, and approximately 2,000 stock watering claims.
📍 Idaho | Snake River System
Clean Water Act
Supreme Court dramatically narrowed Clean Water Act jurisdiction by ruling that only wetlands with a "continuous surface connection" to navigable waters are protected. The decision rejected the EPA's "significant nexus" test and potentially removed federal protection from millions of acres of isolated wetlands, leaving their protection to state discretion.
📍 Idaho | Supreme Court Decision
Interstate Compact
Supreme Court found Nebraska knowingly violated the Republican River Compact by exceeding its water allocation during 2005-2006. Nebraska was ordered to pay Kansas $5.5 million in damages and partial disgorgement. The Court also reformed accounting procedures to properly account for imported water from outside the basin.
📍 Kansas, Nebraska, Colorado | Republican River Basin
Clean Water Act
Supreme Court held that the Clean Water Act requires a permit when pollutants reach navigable waters through groundwater if the discharge is the "functional equivalent" of a direct discharge. The case involved Maui County's wastewater injection wells that discharged into the Pacific Ocean through subsurface pathways.
📍 Hawaii | Supreme Court Decision
Interstate Water Transfer
Supreme Court upheld Oklahoma's right to restrict water exports to Texas, ruling that the Red River Compact does not prohibit states from limiting out-of-state water sales. The decision affirms state sovereignty over water resources and has implications for water-scarce regions seeking to import water from neighboring states.
📍 Texas, Oklahoma | Red River Basin
Tribal Water Rights
Wyoming Supreme Court recognized the Wind River Tribes' (Eastern Shoshone and Northern Arapaho) federal reserved water rights with a priority date of 1868, the date of the treaty establishing the Wind River Reservation. This was one of the first state court adjudications to quantify tribal water rights using the practicably irrigable acreage standard.
📍 Wyoming | Wind River Reservation
Tribal Water Rights
Oregon Supreme Court affirmed that the Klamath Tribes hold federally reserved water rights with an 1864 priority date for hunting, fishing, gathering, and cultural purposes. The decision recognized instream flow rights necessary to support tribal fisheries and cultural practices, going beyond traditional agricultural uses.
📍 Oregon | Klamath Basin
Tribal Water Rights
After decades of litigation, New Mexico approved a comprehensive settlement for the Pueblos of Pojoaque, Nambe, San Ildefonso, and Tesuque in the Pojoaque Basin. The settlement provides for regional water infrastructure and quantifies tribal water rights, ending one of the longest-running water rights disputes in New Mexico.
📍 New Mexico | Pojoaque Basin
Tribal Water Rights
Historic settlement recognized Taos Pueblo's water rights and included provisions for watershed protection and water quality enhancement. The agreement balanced tribal water needs with existing non-Indian water users and environmental concerns in the Rio Pueblo and Rio Hondo watersheds.
📍 New Mexico | Taos Pueblo
Tribal Water Rights
Arizona settlement resolved water rights claims for the Gila River Indian Community, providing water delivery infrastructure and water supplies. The settlement was one of the largest tribal water settlements in history, addressing decades of water deprivation and enabling economic development.
📍 Arizona | Gila River Basin
Tribal Water Rights
New Mexico settlement recognized the Jicarilla Apache Nation's water rights in the San Juan River Basin. The agreement provided for infrastructure development and quantified tribal water rights, resolving longstanding disputes with non-Indian water users.
📍 New Mexico | San Juan River Basin
Tribal Water Rights
Washington adjudication recognized the Yakama Nation's treaty-based water rights for fishing, hunting, and gathering purposes. The decision extended Winters doctrine water rights to support tribal treaty-reserved activities beyond traditional agricultural purposes, recognizing instream flows for fish habitat.
📍 Washington | Yakama Reservation
State Sovereign Lands
Supreme Court ruled on whether Montana owns riverbeds under three dammed rivers, affecting rent payments from PPL Montana hydroelectric dams. The Court held that the federal government retained ownership of riverbeds that were not navigable at the time of statehood, limiting state claims to sovereign lands.
📍 Montana | Supreme Court Decision
Federal Reserved Rights
First Supreme Court case extending federal reserved water rights doctrine to groundwater. The Court protected water levels in Devil's Hole, a geothermal pool in Death Valley National Monument critical for an endangered pupfish species, against nearby groundwater pumping.
📍 Nevada | Death Valley
Interstate Dispute
South Carolina sought to invoke the Supreme Court's original jurisdiction over Catawba River water rights, alleging North Carolina water withdrawals harmed South Carolina. The Court denied South Carolina's motion to file a complaint, declining to hear the interstate water dispute.
📍 South Carolina, North Carolina | Catawba River
Interstate Compact
Kansas filed suit in the Supreme Court alleging Colorado violated the 1949 Arkansas River Compact through excessive groundwater pumping and inadequate river deliveries. The case involves complex issues of groundwater-surface water interaction and compact interpretation.
📍 Kansas, Colorado | Arkansas River Basin
Tribal Water Rights
California adjudication involving the Agua Caliente Band of Cahuilla Indians' groundwater rights in the Coachella Valley. The complex case addresses tribal reserved water rights in an over-drafted groundwater basin serving major agricultural and resort development.
📍 California | Coachella Valley
Tribal Water Rights
Washington State Legislature approved water rights compact with the Spokane Tribe, quantifying tribal water rights and providing funding for water infrastructure. The compact resolves claims to Chamokane Creek and groundwater on the Spokane Reservation.
📍 Washington | Spokane Reservation
Tribal Water Rights
Nevada district court adjudication determining water rights for the Walker River Paiute Tribe. The case addresses tribal reserved water rights and their priority in relation to other water users in the Walker River Basin, which flows into Walker Lake.
📍 Nevada | Walker River Basin
Tribal Water Rights
Ongoing Arizona general stream adjudication involving the Hopi Tribe, Navajo Nation, and other tribes in the Little Colorado River watershed. This massive adjudication addresses thousands of water right claims and has significant implications for tribal water security in an arid region.
📍 Arizona | Little Colorado River