In Colorado, it is generally illegal for most people to capture and use rain water or snow melt coming off their roofs. To some, this may appear wrong-headed; isn't it efficient and sensible to use small amounts of water where it falls? The reasons behind the prohibition are complicated legal principles that form the foundation of our entire water law system.
Last year, state Sen. Chris Romer, D-Denver, proposed to allow homeowners to collect run-off from their houses, but the proposal was defeated by water users' groups, citing concerns that run-off capture will impair legally recognized and highly prized water rights belonging to municipalities, agricultural users and individuals. This year, we can expect another legislative proposal to press the same issue.
State Sen. Jim Isgar, D-Hesperus, has announced he will support a measure allowing certain landowners to capture and use roof water. This proposal is smaller in scope than last year's bill, but will again send the Legislature digging into the building blocks of state water law.
Run-off cannot be collected in Colorado under a deeply entrenched legal principle called "prior appropriation" of water. To oversimplify a highly complex system, our water law says water users must get into an orderly line of priority. Whoever "appropriated" (meaning captured and used) water from a stream first has the highest priority on that stream, and so on down the line. Any holder of water rights - including municipalities, corporations and individuals - is assigned a priority date measured by its first use of water. The earliest priority water rights in the state date from the early 1800s, before statehood.
The importance of the priority system shows up when there is not enough water in the stream system to satisfy all the water users in a particular year. In that circumstance - which is every year in most Colorado watersheds - those with earlier priority dates get to take their share of water before the next person in line. The last in line is often left high and dry.
Water rights are attached to a particular stream system, which is made up of a major river and all its feeder streams and sources. Most stream systems in Colorado are "over-appropriated," meaning all of the water in that system - and more - is spoken for. Locally, the La Plata is severely over-appropriated and segments or tributaries of other local rivers can be at certain times of the year. The disputes and bargaining among water rights holders in line for a scarce resource are understandably vigorous and complex.
So where does roof runoff come into the picture? It, too, is part of the priority system because it, too, is part of the state's waters. Colorado law presumes all water in the state "finds its way to the stream in the watershed in which it lies." In other words, all water in the state, with very few exceptions and including water coming from above, is part of a particular river system and, therefore, is governed by the priority system and can only be used after adjudication by the court.
Sen. Isgar's proposal is meant to apply only to landowners with wells that are exempt from the prior appropriation system. Exempt wells are generally small wells for limited uses that serve landowners without access to municipal water systems. Because of the size and usually rural location of these wells, they are deemed to have minimal or no impact on river systems and therefore are not subject to the prior appropriation system. By limiting itself this way, Isgar's proposal is modest in comparison with Romer's earlier proposal. Nonetheless, even this relatively simple proposal challenges bedrock legal principles.
Proponents of roof water capture argue it is an efficient use of resources and doubt the water collected has any noticeable impact on the levels of rivers and reservoirs. They may point out that a primary use of captured water is likely to be watering of lawns and gardens, which effectively returns the water to the system. Opponents argue Colorado water law is a complex architecture that has painstakingly evolved over 150 years to allow maximal use of a scarce resource. To preserve the precarious balance we have struck, opponents would argue it is important to observe the component principles scrupulously.
Again this year, the Legislature will be drawn into delving into historical and foundational features underlying our management of the state's waters. Although the amounts of water at issue may be small, the legal niceties involved are formidable.
Kate Burke is an associate attorney at Maynes, Bradford, Shipps & Sheftel, LLP, in Durango.