CITY, COUNTY, FEDERAL OFFICIALS ADDRESS
PACTOLA WATER RELEASES, DOWNSTREAM IMPACTS, WATER RESTRICTIONS
RAPID CITY, SD—City, county and federal officials gathered recently at Sioux Park along Rapid Creek to address recent water releases from Pactola and Deerfield Reservoirs, the increased stream flows in Rapid Creek through Rapid City, shared safety precautions and advice for the public engaged in activities in or near Rapid Creek, and the status of annual water restrictions.
In recent weeks, the Bureau of Reclamation has notified the City of Rapid City to increase water flows out of Pactola Reservoir and Deerfield Reservoir, in response to the Bureau’s management of both reservoirs and the flood control pool at Pactola Reservoir. The public often raises questions as to how the flows are managed, specifically why there may be more notifications by the Bureau to the City to release more water from Pactola and/or Deerfield at a time of increased rain or storm events in the areas.
Attending the press conference were officials with the City’s public works, parks and fire departments, US Bureau of Reclamation, Rapid City/Pennington County Water Rescue Team and Rapid City/Pennington County Emergency Management.
Below are responses to a number of issues and questions raised by the public regarding the frequent releases and impacts on Rapid Creek and the community:
QUESTION: Why is the City releasing water from Pactola Reservoir? Are there issues with Pactola Dam? Why must the water be released?
ANSWER: The Bureau of Reclamation, City of Rapid City, and US Army Corps of Engineers jointly administer the Pactola and Deerfield Reservoirs for municipal, irrigation, fisheries, wildlife, recreation, and flood control purposes. Additional releases are controlled by the Bureau of Reclamation and US Army Corps of Engineers to balance the managed water storage in the reservoir to maximize municipal and irrigation usage, but also to help manage potential flood events and decrease the risk of damage to the reservoirs and downstream banks. There are currently no issues with the Dams from the recent increased flows.
QUESTION: How is the decision made to release more water from Pactola Reservoir and Deerfield Reservoir?
ANSWER: The City of Rapid City works with the Bureau of Reclamation and the US Army Corps of Engineers to monitor incoming flows and storm events to regulate releases from the reservoir. The Bureau and Corps use that information to calculate release rates and notifies the City of Rapid City, which then adjusts the dam’s gates to meet the requests.
QUESTION: How does this year’s water releases compare to releases at the same time last summer?
ANSWER: The stored water levels in Pactola Dam are almost identical to the levels from last year. However, the amount of inflows – the amount of water running into Pactola Reservoir from the watershed above the Reservoir is higher than last year’s inflows at this same time last year. Median inflows are typically around 60 to 65 cubic feet per second. Because of the higher inflows, releases are approximately 60 CFS higher than last year. Median releases are approximately 80 CFS.
QUESTION: Why are the stream flows higher in Rapid City than where the water is released at Pactola Reservoir?
ANSWER: Flows of Rapid Creek through the Rapid City area is a combination of releases from Pactola Reservoir and from inflows from tributaries between Pactola Reservoir and Rapid City. In the last couple days, natural flows into Rapid Creek have increased approximately 10 CFS in comparison to water released from Pactola Reservoir.
QUESTION: Is there concern the increased releases will cause downstream damage to Rapid Creek stream banks?
ANSWER: The Bureau and the Corps of Engineers manage the releases of the water to minimize damage downstream and to assure that there is adequate available water storage space within Pactola Reservoir in the event of a large flood event. The controlled release of water allows for more water to be held at the reservoir in the event of future storm activity. Without regular controlled releases, much more water may need to be released, which would then cause potential damage to downstream banks.
QUESTION: With the increased releases and the recent rain events, Rapid Creek’s stream volume has increased. Is there concern about the public’s safety?
ANSWER: Residents are advised to use extreme caution around Rapid Creek with fast-moving waters and increased water levels. The public is advised to not walk, jog, bike or drive through flooded areas, such as low-lying areas of the City’s bike path. During storm events, flash-flood events and periods of high stream levels, the public is advised to heed warnings of public agencies. Do not cross barricades or avoid warnings of high water levels along Rapid Creek.
QUESTION: Can the public monitor Rapid Creek water levels?
ANSWER: The public can visit the following website to monitor the Rapid Creek stream gages. https://waterdata.usgs.gov/sd/nwis/rt
QUESTION: What does the website information mean?
ANSWER: Of the various data graph points, the most important content to review is the discharge in cubic feet per second at the various sites, such as below Pactola Dam, at Canyon Lake and at Founder’s Park. One cubic feet per second represents approximately 7.48 gallons of water per second or 448 gallons per minute of stream flow. Visitors to the website can see how the discharge rate of cubic feet per second has increased over a period of time. The gage height does not equal the stream depth of Rapid Creek at the site nor does it represent the speed of the water flowing at that site.
WATER RESTRICTIONS (STATUS)
City officials remind homeowners Rapid City’s annual water conservation measures are in effect from June 1-August 31.
No watering is allowed between 9 a.m. and 6 p.m. daily. Odd-numbered addresses are allowed to water on odd-numbered calendar days. Even-numbered addresses are allowed to water on even-numbered calendar days. No outside watering is allowed on the 31st day of any month.
Manual watering with a handheld hose or with a bucket, sprinkling can or other similar container is allowed.
Since the 1990s, the City of Rapid City has instituted mandatory water conservation measures. The purpose is to maintain a conservation philosophy among residents. Water conservation measures are utilized June 1-August 31 each year under normal status conditions. Status conditions include normal, concern, alert and critical stages and are determined by the water levels and inflows to Pactola Reservoir.
The impact of water conservation measures is reflected in the average daily use of water per person in Rapid City. In the 1990s, prior to implementation of annual water conservation measures, the average daily use of water per person in Rapid City was 168 gallons. Today, that average has dipped considerably to around 132 gallons. A ‘Please Use Water Wisely’ pyramid of 168 water jugs, reflecting the daily use of water per person in the 1990s, is on display at the Mountain View Water Treatment Plant.
For more information or questions about the City’s water restrictions, contact the Rapid City Water Office at 394-4162.