Hydralife Results: How City Park Golf, Denver's Historic Municipal Course, Managed Its Irrigation Pond Without Chemicals

City Park Golf Course is one of Denver's landmark municipal courses. Set within historic City Park and operated by the City and County of Denver Division of Golf, it was rebuilt in 2017 and reopened as a modern course carrying a long civic history. Keeping a course like that in shape is a public trust, and in 2024 the City's Director of Agronomy and Superintendent took on its irrigation pond with a new, biological approach. This is the story of that pond, and of a team willing to try something different on a flagship property.

A flagship municipal course

City Park Golf Course belongs to the City and County of Denver, and it is one of the busiest and most recognizable public courses in the city. After a full reconstruction in 2017, the course reopened with new turf and new infrastructure, and with the ordinary challenge that follows major earthwork: soil that has lost much of its living biology. The people who manage it answer to the public, which raises the bar on every decision, including how the water is handled.

An irrigation pond incoculated with phytoplankton to reduce nutrient load and provide a biostimulant to the soil.

The irrigation pond that runs the course

The heart of the irrigation system is a pond that was roughly twelve feet deep and that serves as the water source for the entire course. It is fed by effluent from a large wastewater treatment facility, which means it arrives carrying nitrogen and phosphorus. During watering the pond pumps about 1,200 gallons per minute across roughly eight hour cycles, drawing the water down a foot or more each night before it refills. By late summer 2024, with high nutrients and heat bearing down, the pond carried excess nuisance algae and was not thriving.

A team ready to try something new

The pond had been managed for years with chemical treatments, including copper and a diatom fertilizer. Copper algaecides work by killing algae, which returns the dead cells and their nutrient load to the water to feed the next round of growth. That copper is also irrigated into the course's turf. The City and County of Denver's Director of Agronomy and the course's Head Superintendent wanted to test a different idea: a natural, biological approach that works with the water's chemistry rather than against it. That willingness to experiment on a high profile public course is what made the project possible.

How the biological approach works

Hydralife produces live concentrated beneficial phytoplankton. Rather than treating a pond with copper or peroxide, the approach works by competitive exclusion and microaglae that promote wellness. The excess ammonia and phosphate that would otherwise feed nuisance and harmful algae become the food source for a beneficial phytoplankton community that grows quickly and holds nutrients below bloom thresholds. Paired with aeration, the living phytoplankton also significantly increases dissolved oxygen, which supports the health of the whole pond. Because City Park's pond was high in nutrients from it's effluent feed, it was a strong candidate for the method.

What Hydralife did

Late in the season, in July 2024, Hydralife met with the City's Director of Agronomy and the Head Superintendent, sampled the pond, and started a combined cleaning and inoculation program. 100 to 150 pounds of nuisance filamentous algae was removed from the end nearest the golf hole. Through late July and August, Hydralife applied inoculations of phytoplankton totaling around 100 gallons and natural sludge digesting bacteria to draw down the muck bed. Weekly sampling tracked both the effluent flowing in and the water in the pond.

The results

The chemistry moved quickly. At baseline in mid July the pond read ammonia at 0.5 ppm and phosphate at 0.5 ppm, with nitrite and nitrate both elevated. Within about two weeks, by August 3, ammonia and phosphate had each fallen to zero and the water was noticeably improved off the shoreline. The pond held its improved condition even as the effluent flowing in kept carrying ammonia at 0.5 to 1.0 ppm. That gap between the nutrient rich inflow and the far cleaner pond is the clearest evidence of the work: the phytoplankton was consuming nutrients as fast as they arrived, and doing it while the course drew more than 500,000 gallons a night for irrigation.

What the team took away

The City's Director of Agronomy and Head Superintendent reported that they had learned a great deal from the project, that they saw real improvement in water chemistry and clarity, and that they were pleased with the results. The Director of Agronomy expressed interest in bringing the program to additional ponds across the Denver golf portfolio, though the season turned before the work could expand. On a late season pond that had struggled under heat and heavy nutrients, a biological program returned it to a healthier, clearer, better oxygenated condition without adding chemicals.

A second benefit for the turf

Because the treated pond is the irrigation source, the benefit does not stop at the water. Every watering carries living, single celled phytoplankton, two to ten microns in size, out onto the course as bioavailable organic matter. For ground that lost much of its biology in the 2017 reconstruction, that steady delivery of living material is a natural biostimulant, feeding the soil with rich organics that it it cleaned from the water.

Managing a municipal pond, golf pond, agricutlure pond or irrigation pond?

Hydralife works with municipal courses, parks, and private ponds across Colorado, and effluent-fed irrigation ponds are where the approach performs best. If your pond is managing a high nutrient pond and wants a chemical free option, you can reach us at www.hydralife.org or service@hydarlifesolutions.com .