Maximum Beneficial Use: An Effort to Mix Recycled Water and Food Production

For Denver Urban Gardens, one of its most important goals is to provide inner-city children with school gardens, where they can grow their own fruits and vegetables. The organization, which operates more than 145 community gardens in the Denver area, works with local school districts, including Denver Public Schools, to create “garden-to-cafeteria” programs. The organization gives kids the opportunity to watch the seeds they plant turn into fresh, healthy food.

Both Denver Water and Denver Public Schools aim to follow the state’s requirement of putting water to its maximum beneficial use. Therefore, instead of using potable water to irrigate school grounds, schools aim to use recycled water.

However, under current state rules, those two goals cannot co-exist. Water regulations prohibit using recycled water on crops intended for human consumption. Because Denver Urban Gardens uses school irrigation water for the on-site gardens, and because Denver Public Schools would begin using recycled water for irrigation at those sites, Denver Urban Gardens could lose a portion of its forty school gardens.

In an effort to meet both goals, Denver Urban Gardens and Denver Water are working together to amend the state regulation to allow the cleanest recycled water to be used on food crops.  “It seems like [our goals] should be complimentary rather than mutually exclusive,” said Shannon Spurlock, Director of Public Affairs and Policy for Denver Urban Gardens.

Proposed Amendment

Pursuant to the Colorado Water Quality Control Act, Code of Colorado Regulation 84 (“Regulation”) sets forth requirements for the use of reclaimed, or recycled, domestic wastewater. The Regulation designates three types of recycled water. Category One is the least treated and most restricted, and Category Three is the most treated and least restricted. The Regulation sets standards for each category, including the maximum allowable level of E. coli. Category One allows the highest level and Category Three requires that “none [be] detected in at least [seventy-five percent] of samples in a calendar month.”  The Regulation also sets the maximum level of turbidity – or cloudiness – for each category.

The categories determine how the water may be used. For example, the Regulation allows users to apply all three categories to non-food crops, but it explicitly prohibits the use of any recycled water on “crops produced for direct human consumption, crops where lactating dairy animals forage, and trees that produce nuts or fruit intended for human consumption.”  That prohibition is where Denver Water and Denver Urban Gardens hope to make a change.

While it is too early in the amendment process to say exactly what the proposed change will be, the organizations are looking at potential changes to Regulation 84 to determine the best way to irrigate food crops with recycled water.

Potential for Pushback

Proponents are preparing for concerns from regulators, from community members, and from people in agriculture, but the concerns do not necessarily stem from the same reasons.  The organizations anticipate that the Commission and the public will have concerns about using recycled wastewater directly on food crops. However, amendment proponents plan to point out that other states already allow the use of disinfected, recycled water on food crops, and they are doing so without making people sick.

Take, for instance, Monterey County in California, where farmers have used recycled water to irrigate fruits and vegetables intended for raw consumption for nearly twenty years. In order to allay consumers’ fears of using recycled wastewater on food, researchers conducted an eleven-year pilot program to study the potential for contamination.  Finding no signs of such a danger, the area’s agricultural industry now heavily relies on recycled water.

Because amending the Regulation would also allow farmers to use recycled water on their own crops, proponents also point out that using recycled water would be a lucrative irrigation alternative. According to those in favor of the amendment, the change would allow farmers to cut down on their annual costs while getting the most out of their water rights.

Even so, farmers may have concerns over how recycled water might affect their water rights. Denver Water and Denver Urban Gardens hope to make it very clear that using recycled water would have no impact on existing rights as long as farmers continue to use the same designated amount of water. Therefore, changing the type of water they use on crops would not require them to apply for alterations to their existing rights and would allow them to continue to use their water rights fully.

Path Ahead

According to the Environmental Protection Agency, the United States only reuses about eight percent of wastewater. Proponents say tapping into this underutilized resource is a worthy goal, especially in places like Colorado, where droughts take a heavy toll on agriculture.

Denver Water and Denver Public Schools say they still have a long road ahead, but the first step is getting Commission’s permission to proceed.  At a May hearing, Colorado’s Water Quality Control Commission (“Commission”) opted to postpone its decision on whether to modify the Regulation until at least October. At that point, the Commission and the Water Quality Control Division will assess whether funding is available to go through the amendment process. After that, the organizations will come up with a proposed amendment, seek public input, and work with water experts and water districts to ensure that the recycled water is fit for its new purpose.

Even if the Commission sends the proponents back to the drawing board, they say they will continue their effort to amend the rules.  “This won’t be the end of the road regardless,” said Damian Higham, a recycled water specialist for Denver Water.

Whitney Phillips, J.D. Candidate, 2016, University of Denver Sturm College of Law

Image: A hydroponic greenhouse with micro irrigation in California, located ¼ mile from the Pacific Ocean’s Monterey Bay)Flickr user U.S. Dept. of Agriculture, Creative Commons.




Hudson Sangree, California looking to recycled water to ease drought concerns, THE SACRAMENTO BEE (April 14, 2014, 12:00 AM),

Interview with Bahman Sheikh, independent water consultant (March 23, 2016).

Interview with Damian Higham, recycled water specialist for Denver Water (March 24, 2016).

Interview with Shannon Spurlock, director of public affairs and policy for Denver Urban Gardens (February 4, 2016).


Reclaimed Water Control Regulation, 5 Colo. Code Regs. § 1002-84 (West 2016).
The Mission and History of Denver Urban Gardens, DENVER URBAN GARDENS,