6 municipalities contributed data for 40 locations in 2023 to the Partnership.
2023
Executive Summary
The Keep It Clean Partnership (KICP) is made up of six partner communities: the cities of Boulder, Longmont, Louisville, and Lafayette, the town of Superior, and Boulder County. KICP staff collaborate with these communities and other organizations with the goal of improving watershed health.
One way that KICP fosters watershed health is by assembling data collected by the partners to evaluate annual and long-term trends throughout the Boulder St. Vrain watershed. This report focuses on data collected in 2023 as described in the KICP coordinate monitoring plan and how it compares to past periods.
Read more about the KICP collaborative monitoring program and see the last 2019 Water Quality Report (PDF)
To access other past reports, please contact Cristina Ramirez at [email protected].
Monitoring Locations Map
The map below shows the extent of the Boulder St. Vrain watershed monitored by KICP Partners and the location of routine monitoring sites. To explore this information more actively, try out the interactive monitoring locations map where you can find out more information on each monitoring site, view data collected for each site, and also explore nearby USGS and State streamflow monitoring stations.
Data Collection Highlights
In 2024, the KICP created this online water quality report to make water quality data more accessible and easier to understand. Highlights and key findings from the analysis of the 2023 data include:
Over 5,000 water quality observations were analyzed for 60 water quality parameters.
Nutrient concentrations are higher downstream of wastewater treatment facilities.
Over the 2018-2023 study period, most pollutant concentrations remained stable or decreased throughout the watershed.
Non-point source pollution influences on E. coli levels, metals concentrations and conductivity are not well understood.
Partners should continue existing monitoring efforts and address pollution through compliance with their respective municipal stormwater (MS4) and wastewater (NPDES) permits. As opportunities arise to do so, partners may consider expanding monitoring efforts to better understand and reduce non-point source pollution.
Precipitation and Streamflow
In 2023, the watershed experienced nearly double the historical average precipitation in the months of May and June.More about Precipitation
Streamflow reflected the high rainfall in May and June but was near historical averages the rest of the year.More about Streamflow
General Water Quality
Key influences on general water quality parameters include high flows due to spring snow runoff and storm events. High flow conditions tend to dilute certain parameters including hardness, alkalinity and conductivity. Otherwise, the watershed has fairly elevated levels of these parameters due to natural geologic conditions. High flow events can also transport sediment, stir up stream beds and erode stream banks, leading to increased suspended solids. Read more about General Water Quality
pH and Dissolved Oxygen values typically attain stream standards year-round in all streams. There were periodic exceedances of the pH standard in some locations where high dissolved oxygen was also observed. Treated effluent outfalls have minimal impact on these parameters.View Dissolved Oxygen Boxplots
Hardness is strongly influenced by the soft water of spring snow runoff, which lowers hardness (as well as alkalinity and conductivity) in April, May and June.View Hardness Graphs
Dissolved Organic Carbon serves as a primary food source for aquatic microorganisms, and high concentrations can indicate organic pollution. DOC levels in Boulder and St Vrain creeks are healthy in all reaches. DOC is not monitored in Coal Creek.View DOC Graphs
Total Suspended Solids are generally low throughout all the streams. Higher levels in 2023 can be explained by seasonal runoff and increased flow conditions due to elevated precipitation which temporarily stirs up solids from the stream bottom.View TSS Graphs
Alkalinity and Conductivity values are highest in the upper-most measured reach of Coal Creek, but still at healthy levels and likely influenced by natural geology. Alkalinity and Conductivity tend to increase from upstream to downstream through urbanized areas. Treated Louisville effluent discharge tends to lower Conductivity in Coal Creek by over 40%, to levels similar to the other streams.View Conductivity Graphs
Nutrients
Nutrient values are generally lower during periods of high streamflow and higher during periods of low streamflow. This was seen clearly in the 2023 data, with nutrients trending lowest in June when runoff was at its peak from snowmelt and weeks of high precipitation. Nutrient levels were generally higher during low flow months, especially the winter, when streamflows were lower in 2023 than most prior years.
Effluent from wastewater treatment facilities can have a significant impact on nutrient levels, especially when facilities are treating a large amount of water. Additional nutrient standards are anticipated for streams in this watershed in the next decade, and current conditions could be a concern. Some wastewater treatment facilities in the watershed have invested significantly in reducing nutrients in treated effluent. Mitigating or preventing inflow of nutrients to the watershed will continue to be a major focus in future years. Read more about Nutrients
Total Nitrogen concentrations increase upstream-to-downstream throughout the watershed, influenced predominantly by treated effluent discharge points. Some increases were seen during higher flows after storm events, suggesting Nitrogen also enters these streams via non-point-source runoff.View Nitrogen Graphs
Total Phosphorus concentrations show similar annual averages when compared to past years, across most locations. Nutrient reductions have historically been a focus for the basin and will continue to remain so, including strategies to address wastewater effluent discharges and non-point sources.View Phosphorus Graphs
E. coli
Escherichia coli (E. coli) is a type of bacteria found naturally in the environment and in the digestive tracts of animals and humans. E. coli is often harmless, but persistently high levels can indicate an increased risk of illness when recreating in a waterbody. E. coli is carefully monitored by KICP in the watershed. Read more about Bacteria and E. coli
E. coli exceedances are a common problem across the Front Range, Colorado, and the United States. All streams monitored by KICP periodically exceed the level of E. coli deemed safe for recreational use by the U.S. Environmental Protection Agency. Typical sources of E. coli in urban streams include wildlife, pets, trash, and human influence.
Recreate safely: Exposure to E. coli and other microorganisms is a risk when wading or swimming in any natural water body. Most types of E. coli do not cause illness, but there are strains that can cause gastrointestinal illness, and E. coli can be an indicator of other pathogens that can make people sick. Tips are provided in this section to reduce the chance of getting sick.View E. coli Graphs
Metals
Metal concentrations are variable but at generally healthy levels throughout the KICP watershed. Metals commonly found in municipal effluents were predictably elevated downstream of treated wastewater effluent outfalls, but not to a harmful degree. Most metal concentrations also trend upward slightly from upstream to downstream, likely due to mineralization of the streambed; however, this has not been studied in this watershed. Read more about Metals
Copper concentrations increase slightly from upstream-to-downstream both in 2023 and in the 5-year averages. These increases correlate with the locations of effluent outfalls, however concentrations in the effluent are well within standards and effects on the streams is not harmful.View Copper Graphs
Arsenic tends to increase upstream-to-downstream, likely due to hydrogeologic conditions; treated effluent discharges tended to have lower concentrations than the receiving water.View Arsenic Graphs
Selenium concentrations in Boulder and St. Vrain Creeks in 2023 were similar to the past 5 years, generally increasing from upstream-to-downstream. Effluent outfalls do not appear to affect these levels, and they are likely more influenced by hydrogeologic conditions.View Selenium Graphs
Silver concentrations are low throughout the watershed. Stream standards for dissolved silver are calculated based on hardness and drop significantly when hardness is also low. During snowpack runoff hardness drops low enough that dissolved silver occasionally measures between the chronic and acute standards.View Dissolved Silver Graphs