Does Durango need a new water treatment plant?

Residents paying for Lake Nighthorse facility, but no construction timeline set

Enlarge photo

David Holub/Durango Herald illustration

Water rates for Durango residents increased steeply in recent years to pay for upgraded infrastructure, including a new water treatment plant at Lake Nighthorse, that a local water engineer says may not be necessary.

But city staff said the Ridges Basin Water Treatment Plant, estimated to cost $55 million, is necessary to serve a growing population, allow the city to update its existing water treatment plant and provide a backup source if the Florida and Animas rivers became polluted or run low.

City water users saw rates increase by 55 percent in 2015 and 10 percent each year in 2016 and 2017. The city originally planned a 32 percent water increase in 2016 and a 2 percent increase in 2017, but the price was scaled back because needs were being met.

Some customers have paid hundreds of dollars for water and stopped watering their lawns as a result of the increased rates.

John Simpson, a water engineer in Durango, is concerned residents are paying for a plant based on outdated data and with no immediate date set for when it will be built.

It’s unclear what water rates would have been had the Ridges Basin plant not been factored into the city’s infrastructure improvement plan. That’s because additional capital items would need to be added, including a major reconstruction to the existing plant to provide for continued operation, according to an email from City Manager Ron LeBlanc. The email was sent in response to several questions asked by The Durango Herald; LeBlanc said several staff members contributed answers to the questions.

While a timeline for the project has not been set, the city is in negotiations with the La Plata-Archuleta Water District and other partners to build the proposed plant, the email said. Both the city and the district own water in Lake Nighthorse, and they could split the cost of a new plant based on water usage.

It’s possible the plant could be built in the next five to 10 years, said water district manager Ed Tolen. But the city will likely determine the timing of the project, he said.

The timeline of the project depends on the construction of a sewage treatment plant in Santa Rita Park, land acquisition, design of a new plant, completion of an updated water master plan and voter approval of a city bond needed to build the plant. Paying cash is not feasible.

“We can only reasonably oversee construction of one plant at a time,” LeBlanc’s email said.

The need for the new water treatment plant was identified in a 2007 water master plan. It predicted the city would need to serve about 40,000 customers per day with 21.9 million gallons of water by 2040. The city water system currently serves about 22,000 people.

The existing plant can treat only 14 million gallons per day, and the master plan recommends a second plant to meet peak seasonal needs.

Simpson said the city’s water master plan should be revisited and updated before the city puts resources into a new water treatment plant.

“I don’t want this council to be known for forcing the citizens to pay for a ‘Water Treatment Plant to Nowhere,’” Simpson wrote in an email to the mayor in May.

It’s possible the city may not need as much water as projected in 2007 because Durango is expected to grow more dense versus sprawl outward, which means fewer lawns and less irrigation, which really drives water use, Simpson said.

“It’s time to really look at demands now and maybe adjust,” he said.

Simpson used as an example a water master plan written for Montrose, a town on the Western Slope about 100 miles north of Durango, which estimates that the city will need a maximum of 14 million gallons per day to serve 40,000 people.

The city of Durango’s 2007 master plan found average daily demand for water declined from 1970 to 2005. Annual audits show fairly flat water usage from 2006 to 2016, ranging from about 3.2 million to 3.9 million gallons per day on average.

“As we have grown in population, our demands keep dropping as people stop watering yards,” Simpson said.

The decline in usage during the last few years could be attributed to wet summers, said Dave Ferguson, water treatment plant superintendent.

The city plans to update its water master plan after the stormwater master plan is complete, which was budgeted to happen this year.

In addition to increasing capacity and providing redundancy, a new water treatment plant will allow the city to upgrade its water treatment plant near Goeglein Gulch Road, city staff wrote in their email.

Simpson questions whether enough study has gone into upgrading the existing plant to meet city needs.

“If taking the plant off line is required, then why doesn’t every town in the nation have two plants?” he asked in an email.

It would be difficult to update the plant because it needs to keep running 24/7.

“It could be done, but it would be exceptionally ugly, convoluted and high-risk,” Ferguson said.

The plant has too many single points of failure, where there is not an alternative pipe for the city to use while they replace existing pipe, and so the city would have to put in a lot of temporary bypass piping to update the pipe.

“The work area would be so busy you couldn’t move around,” Ferguson said.

The city also plans to make the Ridges Basin plant a backup if the Florida and Animas rivers were compromised by wildfire or drought.

“Durango is extremely fortunate to be at the base of high mountains, having a large drainage basin, and not having any competing municipalities downstream,” Simpson said.

In addition to the rivers, there are groundwater sources and the existing city reservoir that could be used, he said.

When people aren’t irrigating during the winter, the city uses about 2 million gallons per day. At that rate of consumption, the reservoir can supply the city for about 40 days, Ferguson said.

The city’s water rates are based on a 2014 study that took into account a list of construction projects not yet built, including their timing and estimated cost. The study anticipated the first phase of the Ridges Basin Water Treatment Plant construction starting in 2017.

The city expects to collect data for the updated rate study in 2018 and update it in 2019, LeBlanc said in his email.

When water rate increases were introduced, Durango City Council intended to encourage water conservation through a tiered system. The fee structure charges customers at a higher rate for the more they use, and the fee structure goes up during the summer when water usage is highest, according to the city’s website.

But that may not be the best strategy, because if the city saves water from the rivers this year, it does not benefit residents next year, and it may encourage people to put in impermeable surfaces instead of grass, and grass helps manage runoff, Simpson said.

What’s more, residents are largely unaware of when they have crossed from one water billing tier to the next.

“People don’t know where they are in the system; they just get this big, fat bill,” Simpson said.

mshinn@durangoherald.com

A water engineer in Durango questions whether the city of Durango needs to build a new water treatment plant. John Simpson is concerned residents are paying for a plant based on outdated data and with no immediate date set for when it will be built. City residents have seen their water rates increase by 55 percent in 2015 and 10 percent each year in 2016 and 2017 to pay for it. Enlarge photo

Jerry McBride/Durango Herald file

A water engineer in Durango questions whether the city of Durango needs to build a new water treatment plant. John Simpson is concerned residents are paying for a plant based on outdated data and with no immediate date set for when it will be built. City residents have seen their water rates increase by 55 percent in 2015 and 10 percent each year in 2016 and 2017 to pay for it.

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