CA WATER LAW SYMPOSIUM: An overview of California water rights

California water law is complex, governed by both state and federal law, part property law and part environmental law. Adding to this complexity is the existence of a large number of federal, state and local agencies which play a role in the allocation and management of the state’s water resources.

At the 2019 California Water Law Symposium, Professor Dave Owen from UC Hastings gave the following overview presentation of California water rights, including types of water rights, governing agencies, and sources of regulatory authority, as well as a brief overview of the 2014 Sustainable Groundwater Management Act.

Dave Owen began with a precipitation map of California, noting that the precipitation occurs primarily in the north and in the mountains; significant parts of California are very dry and all of California is quite dry in the summer months.  Those precipitation patterns are reflected in the state’s river systems; there are rivers and surface waterways over most of the state, but most of the flow is concentrated in the Sacramento River valley and on the Northwest Coast.

One of the challenges that creates for California water is that the population centers are primarily in the southern part of the state and along the coast, and one central challenge of California water law and California engineering has been figuring out how to facilitate the movement of water from the places where it naturally occurs to state’s major population centers.  The primary use of water is for agriculture, which faces similar challenges because the primary agricultural regions of the state are relatively dry.

In order to deal with this hydrology, the state has built massive amounts of infrastructure designed to move water around the state from places where it naturally occurs to places where it is needed.  The map on the slide is just a partial showing of the different water infrastructure systems that have been built.

The point here is first, there’s a lot of infrastructure and a tremendous amount of engineering went into this, but also, a lot of what California water law does is facilitate this movement of water around the state,” said Mr. Owen.  “Then another important and central task of California water law is to figure out how to deal with the environmental impacts of taking water out of the places where it naturally occurs and putting it someplace else.”

He then presented a map (lower, left) that shows the land surface area that provides surface water to Los Angeles, noting that he could show similar maps for other California cities as a lot of them have similarly huge reach.  “The point is that water falling on the slopes of the Trinity Alps in far northern California can very easily wind up being drunk in San Diego or Los Angeles,” he said.  “We’re that interconnected.”

When water falls on the ground, much of that water then infiltrates into the ground until it hits the water table, which is the level at which all the pore spaces are filled with water rather than air, Mr. Owen explained.  It then typically flows laterally, generally very slowly, sometimes comes back into surface water or sometimes sits and is eventually pumped out through wells. Aquifers are productive subsurface deposits that are filled with water and from which water can be pumped.

There are a lot of aquifers in California; some are quite deep and hold tremendous amounts of water, so a lot of water needs are met with groundwater rather than surface water, particularly during drought years.

It’s important to also understand that California’s water systems are changing because of climate change.  The most important reservoir that the state has is the Sierra Nevada snowpack; it is getting smaller, and it’s likely to get considerably smaller in years to come as the impacts of climate change increase.

This is a fundamental challenge which basically makes everything else we do in California water law more difficult than it would otherwise be,” said Mr. Owen.


California water rights can be divided up into surface water rights and groundwater rights.

Surface water rights

Mr. Owen addressed surface water rights first.   There are two major types of surface water rights:

Riparian rights which are rights held by landowners whose property is adjacent to a waterway; they are entitled to a reasonable use of water by virtue of their ownership of the land.

Appropriative rights are established based on temporal priority rather than land ownership, which means that the first person to take water out of the river system and put it to beneficial use has a more senior right than those who come along later.  Those with the senior water rights take their full amount before those with junior rights get to take anything.  Appropriators since 1914 are required to get a permit from the State Water Resources Control Board.

He acknowledged there are other types of surface water rights, but riparian and appropriative water rights are the most important ones.

Now you might wonder why California has both riparian and appropriative water rights, as they might seem a little bit incompatible in some ways.  “The short answer is that in the 19th century when other Western states were pretending that riparian rights never existed, the California Supreme Court was a stickler and said no, we have to respect existing riparian rights, so we’ll simply have to have both,” he said.  “And that’s created challenges for California water lawyers ever since, but it is the law of the state.

Groundwater rights

There are also different kinds of groundwater rights:

A correlative water right is a water right held by an overlying landowner that entitles that overlying landowner to a reasonable share of the aquifer, given the needs of other competing correlative users.

Appropriative water rights are assigned on the basis of temporal priority and they can be held by anybody, not just an overlying landowner.  But, in theory, you can only have an appropriative right to groundwater if the needs of the overlying users have already been met, so these rights are subordinate to overlying rights.

Prescriptive rights exist in some parts of California.  It is similar to adverse possession for land.  “There are some places where so much pumping was occurring that essentially everybody was trampling on everybody else’s right, and to sort out this situation, the California courts created this category of prescriptive rights that essentially allows them to diverge from what would have been a system under correlative or appropriative rights and create a new and sort of pragmatic solution to the challenge,” he explained.

Federal water rights

There are water rights in California and elsewhere in the US that are created by federal law; the most important type is what’s known as a reserved right.  A reserved right is created when the federal government reserves federal land for some specific purpose, like an Indian reservation or a National Park.  The amount of the reserved right depends on the primary purposes of that reservation; in other words, the federal government reserves enough water rights to satisfy the reservation’s purposes.  These rights can apply to surface water or groundwater and importantly, they are not lost through non-use.

Where these exist, as a practical matter, they are pretty powerful rights,” Mr. Owen said.


Water law is partly property law and partly regulatory law, so who is in charge?  Who governs water law?

The federal, state, and local governments all have significant roles, said Mr. Owen.

State agencies traditionally have some level of primacy in the field of water law.  The slide is just a partial list of state tasks that highlights the most important ones; among those important tasks are establishing the criteria for obtaining a water right, regulating water use under those rights, managing the State Water Project, and implementing both federal and state environmental laws.

The federal government has many roles; Mr. Owen listed some of them.  The federal government holds reserved water rights, but also has its own water rights.  The federal government through the Bureau of Reclamation manages federal water projects in California, the largest being the Central Valley Project.  The Federal Energy Regulatory Commission (FERC) licenses hydropower projects and implements federal environmental laws.

Local government also has a role, depending on the type of local government.  One type of local government the water district, which is a government entity whose purpose is to supply water, either as a wholesaler or as a retailer; these entities typically hold water rights and then deliver water either to other suppliers or directly to consumers.

Cities and counties are very important; sometimes they are the water supplier, so there can be an overlap between the roles of cities, counties, and water districts.  Cities and counties also plan land use which is very important for determining levels of demand for water, patterns of groundwater recharge, and how water moves across the landscape. Both cities and water districts are increasingly getting involved in groundwater governance.


Mr. Owen then turned to the sources of regulatory authority.

State authority

The California Constitution states that all water rights must be reasonably used, or that rights only extend to uses that are reasonable.

This is bedrock principle for water lawyers, but it’s different from what we do with land,” he said.  “We don’t say that your right to own land ceases if you make some sort of frivolous use of your land, but with water, that is a bedrock legal principle.  Cases under the reasonable use doctrine don’t come up all that often, but for state regulators, this has been an important background source of authority to regulate water uses.”

There is also the public trust doctrine, which is an important part of any water law course and has some practical implications, although not quite as important as some make it out to be.  “The public trust doctrine basically says that some resources including water are held in trust by the state for the benefit of the people, and so in California that means that navigable waterways are trust resources which the state is supposed to manage for several public purposes, including things like navigation, facilitated waterborne commerce, and environmental protection,” he said.  “The doctrine operates both as a constraint on the range of things the state can do with its waterways, and also as a source of regulatory authority.”

There’s also statutory law, both state and federal, that deals with water allocation.  The most important compilation of this law is the California water code, which has a lot of different provisions.  Some of the most important ones deal with water quality provisions, applying for water rights, the criteria for obtaining the water right, and the criteria for changing or transferring that water right.

The California Fish and Game Code also have provisions for protections when stream beds are going to be altered or diversions are going to be taken out of streams and some important provisions for protecting fisheries below dams.

The California Environmental Quality Act or CEQA is an environmental analysis statute that requires state and local agencies to study and disclose the impacts of discretionary projects they are undertaking that might have significant environmental impacts.  It also requires them to identify and adopt if feasible mitigation measures and alternatives that with avoid significant environmental impacts.  It’s a very important procedural statue that also has some substantive bite for water project planning and development.

Federal authority

There are also some different key federal law provisions.

The National Environmental Policy Act or NEPA is the federal counterpart to CEQA; the requirements are essentially the same with some subtle differences except that NEPA has no substantive requirements, Mr. Owen said.  It only requires disclosure and analysis of environmental impacts; it does not require their avoidance.

The Clean Water Act is important to California water management in several different ways:  One is that simply by protecting water from discharges of pollutants, it keeps water cleaner, makes more of the resource available use, and protects environmental quality.  In addition, under the Clean Water Act, the state of California sets water quality standards which are levels of water quality that we attempt to achieve in our waterways, and those water quality standards then get integrated into water right permits.

Some of the most important constraints in water pumping out of the Sacramento-San Joaquin Bay Delta, for example, ultimately come because of water quality standards set under the federal Clean Water Act,” he said.

The federal Endangered Species Act is important as there are a lot of different threatened and endangered species in the state’s waterways, such as salmon and steelhead trout which tend to migrate over huge areas, so it is difficult to do something major with California water without somehow affecting endangered species, he noted.  The Endangered Species Act, some of its key constraints apply directly to the federal government and do not apply to state and local governments; it also prohibits anybody, not just the federal government, from ‘taking’ listed species which basically means harming or killing members of that species.

As a practical matter, these constraints have been very important to water pumping in the Central Valley and the management of a lot of other California rivers,” noted Mr. Owen.

There is also the Federal Power Act which gives the Federal Energy Regulatory Commission authority over hydropower project licensing and relicensing decisions.  “That means that the Federal Power Act is at the center of controversy over things like the Oroville Dam or the dams on the Klamath River or smaller hydroelectric projects throughout the state,” he said.

Lastly, the federal Safe Drinking Water Act is less an environmental statute and more of a public health statute, meaning its focus is not so much on conditions out there in the environment as it is on what comes out of the tap, but the basic goal of the statute is to ensure that managers of public water systems monitor the quality of water that they are delivering to consumers, and meet certain standards in that water quality, he said.


Mr. Owen then gave a quick overview of the Sustainable Groundwater Management Act.  To understand the significance of this statute, it helps to go back a little bit and know what groundwater law was in this state not so long ago, he said.

He presented a slide with quotes from groundwater law in the 19th century which referred to groundwater regulation as the ‘dark arts theory of groundwater regulation’, the idea being that ‘we can’t touch this stuff, nobody understands it and we’re not even sure we want to.’

In California, groundwater remained essentially unregulated at the state level.  In some places, local governments did very sophisticated and effective things to regulate groundwater, such as in Southern California, and courts sometimes were involved in adjudicating groundwater rights, but in the central valley, the state’s primary groundwater using region, there were many areas where there was essentially no regulation at all.  For a long time, people liked it that way, at least within those regions as they felt like it kept them somewhat safe from government regulation.

Many of us wondered if there would ever be statewide groundwater regulation,” Mr. Owen said.  “That was simply an impossible political dream that could never actually occur.

It’s not for lack of importance, he said. Groundwater is crucially important throughout this state and particularly in places like the Southern San Joaquin Valley.  “We have significantly overdrawn some of our groundwater resources, which means we have been taking groundwater out of many areas of the state faster than it is naturally replenished, and that in turn causes big problems.  As you lower groundwater levels, it costs more to pump the water because you have to pay for more energy and sometimes you have to dig deeper wells. If you can’t afford to dig a deeper well, you’re out of luck, you don’t have any water anymore.  If you can still get water out of the well, the quality of that water often gets degraded as we get deeper into the aquifers.  There are environmental impacts because that water is no longer recharging into surface water ways, and then finally of course, the water is gone because we’ve used it now and pumped it out, it’s not there for potential future use.”

So for all of these reasons, at the end of 2014, the state finally enacted the Sustainable Groundwater Management Act which is designed to provide a statewide system for groundwater regulation.

Mr. Owen then gave a brief overview of the legislation.

  • Local groundwater management, state oversight and support:  Even though it is a state statute, it still envisions a primary local role in implementing the law, so the idea is that local governments will take the lead in implementing SGMA and the state will provide oversight and support.
  • Formation of groundwater sustainability agencies:  The legislation provides for the creation of Groundwater Sustainability Agencies (or GSAs) which are local agencies that will take the lead in regulating groundwater use.
  • Creation of groundwater sustainability plans: The Groundwater Sustainability Agencies are required to create Groundwater Sustainability Plans (or GSAs) which are plans to bring groundwater into sustainable levels of use.
  • Groundwater Sustainability Plans must achieve sustainability goals by 2040 or 2042.

One last important thing to know about SGMA that isn’t mentioned here is that SGMA is an additive statute, or in other words, it’s in addition to whatever regulatory requirements existed for groundwater,” Mr. Owen said.  “It is not designed to occupy the field so it doesn’t replace the previous regime of groundwater rights and it doesn’t displace other regulatory programs or environmental laws with some fairly limited exceptions.”


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