Stream ID

Minnesota Department of Natural Resources (MNDNR) stream ID M-055-014  

Minnesota Pollution Control Agency (MPCA) stream ID S009-308. This link provides available information on stream quality. Although this is the most downstream sampling site, Bluff Creek has other sites upstream that were sampled for studies whose data are identified in the adjacent table. 

Bluff Creek is a 6.8-mile-long (10.9-kilometer) stream in Carver County, Minnesota, that drains a 5.8-square-mile (1500-hectare) watershed (RPBCWD 2019). After flowing down the northern slopes of the Minnesota River Valley, it empties into Rice Lake, which drains into the Minnesota River. Much of the creek flows through low-density residential areas. Current land use is mostly open space and residential, with the rest being farmland, commercial, and roadways (RPBCWD 2019). As of 1994, the City of Chanhassen identified Bluff Creek as a valuable resource for recreation, wildlife, and aesthetic incentives (City of Chanhassen 2021). 

The Lower Minnesota River Watershed District funds routine sampling of Bluff Creek. Selected results from the analysis of samples collected from Bluff Creek at site S009-560 near where it empties into Rice Lake were obtained from the Metropolitan Council Environmental Services websiteⁱ  and are summarized in the following graphs. 

Monitoring Data

Streamflow

Samples collected from Bluff Creek’s streamflow are shown below. The creek’s flow rarely drops below 1 cubic foot per second (0.028 cubic meters per second) and occasionally exceeds 100 cubic feet per second (2.83 cubic meters per second). 

Temperature

The water temperature of Bluff Creek is shown in the graph. Temperatures at the sampling sites fluctuate seasonally, rarely exceeding 68° Fahrenheit (20° Celsius) in the summer and stays near 32° F (0° C) in the winter. 

Dissolved Oxygen

Dissolved oxygen (DO) concentration measurements show that Bluff Creek remains well oxygenated. Aquatic animals typically need at least 5 mg/L of DO to survive (MNDNR 2021). Seasonal fluctuations are normal because oxygen’s solubility changes with the water’s temperature. 

Turbidity

The adjacent graph shows the turbidity, a measure of water clarity, of Bluff Creek. High turbidity in a stream indicates cloudy water that carries large amounts of fine material that interferes with visibility. Low turbidity implies that less sediment is carried by the stream. Streams receiving runoff tend to be turbid when they might otherwise run clear.  

Various methods have been used since 2010 to measure turbidity in Bluff Creek, and the results using different methods are not comparable. Only the most recent measurements made since 2019 are shown in the chart below and are reported in nephelometric turbidity units. 

Chloride

Chloride, a primary component of road deicing and water-softening salt, represents a growing concern for many streams and lakes. The chronic standard for chloride in Minnesota waters to protect cool and warm water fisheries is 230 mg/L (MPCA 2018). Chloride concentrations in Bluff Creek are usually far below the chronic standard but occasionally exceed the standard. Peak concentrations, usually measured in the winter, may result from road-salt runoff. 

Phosphorus

Phosphorus is an essential plant nutrient that is carried by streams. Naturally occurring phosphorus concentrations may be enriched from animal waste and fertilizers, and it often is introduced with runoff. Phosphorus is often associated with sediment but is more available to plants when dissolved in the water. The adjacent chart shows the phosphorus concentrations in samples from Bluff Creek after the water has been filtered to remove the sediment-associated phosphorus.