Resource Ramblings 2006-06

Beaver Creek

Beaver Creek is the main drainage in the park. All other streams (Highland and Cold Spring) flow into it or would if they contained enough flow to do so. Beaver Creek drains an area of approximately 46 square miles. It starts near Pringle and flows east into the park, and then continues southeast to join the Cheyenne River east of Buffalo Gap. However, the flow rarely makes it out of the park as it typically looses its entire flow when it reaches the outcrops of Pahasapa Limestone. This process plays a crucial role in recharging the Madison Aquifer. In April of 1998 I gaged Beaver Creek above and below the loss zone to determine how much of the stream was sinking and determined that the creek above the cave was flowing at 5.67 cubic feet per second (cfs) and below at 1.99 cfs. Thus, the loss zone was responsible for a loss of 3.68 cfs or 27.5 gallons per second. This means that in a 24-hour period 2.4 million gallons of water enter the aquifer via Beaver Creek.

In a 1986 study, Marsha Davis and Dr. Calvin Alexander injected dye into the stream to determine where the water was going. The injection point was where the stream was captured by the aquifer near the intersection of the Centennial and Beaver Creek trails. After one month dye showed up in the Park’s water supply well and persisted for several months, exemplifying the surface to subsurface hydrologic connection.

In the fall of 1990, the USGS installed a stream level recording gage on Beaver Creek just below the confluence with Cold Spring Creek. This station is still in operation and has provided us with over 15 years of continuous flow data
Streamflow of Beaver Creek (1990 thru 2005)
Streamflow of Beaver Creek (1990 thru 2005)

NPS Illustration


In 2002 and 2003 the USGS conducted water quality characterization of the three park streams. In Beaver Creek they found that the water quality was somewhat degraded compared to the other two park streams, indicating that activities outside the park are influencing the quality of the stream. Concentrations of E. coli, fecal coliform, and total coliform bacteria were highest in Beaver Creek. The sediments in the stream contained arsenic concentrations of 9.5 mg/g, exceeding the EPA’s threshold for stream sediments. Phenol, para-cresol, and para-nonylphenol, which are manufactured chemicals found in a number of consumer products, were found in the stream. Cholesterol and caffeine were also found, which indicates an impact of septic system(s) on stream. Even though this all sounds doom-and-gloom, actually the stream overall is in good health. We are mandated to protect our surface and sub-surface water resources, and as such we will continue to monitor the health of our water resources and do what we can to reduce impacts. Unfortunately most of the watershed and activities that are influencing the water quality in Beaver Creek lie outside the park.

Beaver Creek is home to the native creek chub, long-nosed dace, white and mountain sucker, fathead minnow, and the non-native brook trout. In addition to the fish there is a very diverse assemblage of invertebrates. - Marc Ohms

Robin Moth - Hyalophora cecropia
Robin Moth - Hyalophora cecropia

NPS Photo by Dan Foster


Some of you may have seen these beautiful moths in the park lately. The cecropia moth is a member of the sturniidae family, or “giant silk moths” (so named because of their size and the silk cocoons in which they pupate) and is one of the largest moths in North America. Cecropia moths only live about two weeks. They have no mouth parts, as their only purpose in the moth (adult) stage is reproduction. These moths emerge with warm weather in late May to early June. Females emit pheromones that attract males. The males can smell the pheromones from distances of up to a mile away. The larvae of cecropia moths have been reported to feed on different trees and shrubs, especially maple, but they will also feed on ash, elm, apple, willow, birch, poplar, lilac and others.

It is interesting to note that leaving outdoor lights on at night can be detrimental to all moths. Many moths are attracted to light and these giants make easy prey for bats and other nocturnal predators.

If you are lucky enough to see one of these moths, please leave it where you find it. Park resources are for everyone to enjoy. - Dan Foster

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Last updated: April 10, 2015

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