With Yampa River water temperatures exceeding 75 degrees on back-to-back days, the river was closed to all recreators through a voluntary closure Wednesday morning.

Written in a 2019 ordinance, the city’s river policy states that the primary goal with a closure is to protect the health of the river’s aquatic wildlife. To achieve this, the city will impose a voluntary closure when the river drops below a river flow of 85 cubic feet per second, its dissolved oxygen levels average less than 6.0 mg/L at the Fifth Street Bridge for the preceding 48 hours or if maximum water temperatures at the Fifth Street Bridge exceed 75 degrees for two or more days in a row. 

The ordinance’s language for reopening the river is not as clear, leading to confusion as to when recreators can return to river use. The ordinance allows for a reopening once it is determined that conditions have improved for the health of aquatic wildlife, but with no specific standards on when that is achieved. 

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In recent years, conditions have fluctuated near the closure criteria thresholds, making it a challenge to determine when it was OK to reopen. This also caused a rift in communication between the city and commercial outfitters who were eager to hear of the river’s fate.

The question then became, should the Yampa River automatically open once closure criteria are no longer met?

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Colorado Parks and Wildlife’s response was no, the agency believes the fishery requires time to recover from the stress that high temperatures and low flows can impose on the aquatic wildlife. 

In working with CPW and local outfitters, the Steamboat Springs Parks and Recreation Department determined it was time to update the language of the 2019 ordinance and draft specific requirements for reopening the Yampa River. 

Impacts on aquatic wildlife

It is believed that angling activities and recreational tubing on the river while the water is experiencing times of high-end temperatures lead to the degradation of fish health and an increase in fish mortality rates. This can be caused either directly by hooking and handling fish or scaring them away from cooler areas of the water system. 

Low stream flows at this time of year cause the water to warm up quicker and can limit a fish’s ability to access an area with a high-quality habitat and cooler temperatures. Fish exposed to these types of stressful situations for a prolonged period may need more time to recover and require access to a habitat of higher quality to recover at all. 

The issue is, there is not enough data collected on how much time fish need to recover from these situations, leading to more confusion on what parameters to set. 

Reopening guidelines

The solution drafted by Lotic Hydrological and Steamboat Springs Parks and Recreation was presented to City Council at the end of 2023, and combined both the physical and biological ideology into reopening criteria. 

The physical benchmarks for a river reopening include: 

• The daily minimum streamflow, assessed as a one-hour rolling average, is greater than or equal to 85 cfs, according to the U.S. Geological Survey. 
• The two-day dissolved oxygen average concentrations are greater than 6.0 mg/L at the Fifth Street Bridge. 
• The daily maximum water temperature, assessed as a one-hour rolling average, is below 75 degrees, measured at the Fifth Street Bridge. 

The framework suggests that biological information be used as an auxiliary to the physical benchmarks that would be the primary driver for a reopening. This suggestion is due to uncertainty revolving fish recovery time after elevated water temperature events.

To achieve this, the framework lays out several biologically relevant metrics that are meant to add a semi-quantitative perspective on fish behavior and stress levels. 

The framework also requires the use of the Yampa River Water Temperature Forecast Tool, which was developed by Lotic in 2023. The forecast tool produces a five-day projection for the daily minimum streamflow and maximum water temperature in the Yampa River. It creates the data based on a probability distribution of 200 predictions for each day of the forecast period. 

Once the tool and the city determine it is time to close the river, a forecast horizon will be set. The forecast horizon is the date when data will be gathered to determine whether the river can reopen or not. The horizon is recommended to be set at two to four days following the closure.

Along with the forecast horizon is the Earliest Potential Reopen Date, called the EPR, which is established as the forecast horizon plus one day. This means, if it is determined that the river is ready to reopen on the forecast horizon day, then it will become available again to users the following day. 

If closure criteria is met on forecast horizon day, the process restarts with reviewing outputs from the forecasting tool each day until reopening criteria are met. 

Looking ahead, City Parks and Recreation Director Angela Cosby said Thursday afternoon that the department is actively discussing plans to reopen the river and said, if the forecast is correct, the river may reopen as early as this weekend. 

As of 3:45 p.m. Thursday, river temperatures recorded at the Fifth Street Bridge read 69.44 degrees. The river has not exceeded 75 degrees in that area since just after 7 p.m. Wednesday, according to the U.S. Geological Survey.

“We commissioned a study and we are following those procedures,” Cosby said Thursday. “Right now as we follow that, we are evaluating reopening for the weekend if the weather comes in as expected the rest of today and tomorrow. If we get the rain and cool temperatures that the forecast calls for, we’ll likely be reopening for the weekend. If it turns out to be warmer and drier than anticipated, we’ll likely be keeping it closed.”