2025 Report

Regulated Stormwater MS4 Permittees

All municipalities with Municipal Separate Storm Sewer Systems (MS4s) permits from the Colorado Department of Public Health and Environment (CDPHE) in the watershed have adopted stormwater programs consistent with Regulation 72 for development and redevelopment projects within their jurisdictions. Both construction-phase and permanent stormwater control measures are required. Regulation 72 requirements are more stringent than MS4 Permit requirements in Regulation 61 Colorado Discharge Permit System Regulations.

In 2025, the MS4 permittees conducted 10,375 inspections of 2,071 construction sites. In addition, the MS4 permittees required that construction site owners/operators install 44 new permanent control measures that are designed to reduce or eliminate pollutants in stormwater before it enters Cherry Creek or its tributaries.

Further information on each MS4’s program can be found in the links below.

Find out more about MS4 Permittees' programs:

Public Education

In addition to regulating development and redevelopment sites in the Cherry Creek Reservoir basin, MS4 permittees also have programs to educate the public, respond to and eliminate illicit discharges, and reduce or eliminate pollutants in stormwater from municipal operations. Examples of these efforts include:

One thing is Clear (Douglas County, Town of Castle Rock, Town of Parker, City of Lone Tree, Highlands Ranch Metro District, Castle Pines Metro District, Castle Pines North Metro District, Stonegate and Lincoln Park Metro Districts)
Splash (Arapahoe County, City of Cherry Hills Village, City of Centennial, Cherry Creek State Parks, City of Sheridan, Greenwood Village)
Colorado Stormwater Council (CSC)
C herry Creek Stewardship Partners

Above & Beyond

2025 SPLASH Summary

Stormwater Permittees for Local Awareness of Stream Health (SPLASH) is a program to educate the public on simple ways to reduce stormwater pollution and its impact on local bodies of water. Below is the 2025 summary:

Castle Rock Water

Stormwater remains a central focus of general outreach and messaging for Castle Rock Water. Key messages include the "There Is No Poop Fairy" campaign promoting pet waste pickup, education on excessive water use, fertilizer and pollution prevention, and awareness of moving water hazards.

Through targeted outreach in 2025, Castle Rock Water reached 29,000 customers and 200 HOAs with an average 63% email open rate covering topics from stormwater maintenance to source water protection, while engaging 28,000 Facebook and 12,000 Instagram followers with seasonal stormwater, flooding, fertilizer, source water, and ‘Poop Fairy’ content throughout the year.

City of Lone Tree

The City of Lone Tree developed a comprehensive stormwater fact sheet to help residents better understand local drainage systems, pollution prevention, and stormwater responsibilities.

Douglas County

The Douglas County Cooperative for Local Environmental Awareness and Responsibility (CLEAR) program is a regional partnership dedicated to safeguarding Douglas County’s creeks, rivers and lakes through effective stormwater management. By uniting local governments, districts and community partners, CLEAR helps ensure clean water, healthy habitats and compliance with state water quality standards. CLEAR connects the community with the resources and knowledge needed to protect water quality for generations to come. Below is the 2025 summary:

Douglas County also manages the Hazardous Household Waste (HHW) collection program open to all residents of Douglas County, including incorporated areas like Parker, Castle Rock, and Castle Pines. The program encourages the responsible disposal of HHW and provides a year-round collection or convenient drop-off to help prevent improper disposal of hazardous materials which can negatively impact water quality. In 2025, residents dropped off more than 72,000 pounds of materials, with 75% successfully recycled.

Stormwater Permits and Inspections for Construction and Post-Construction Development

1. 1 tier 2, all other work within jurisdiction was tier 1.
2. 1191 written notices of violation including 5 stop work orders.
3. Since 2008
4. This includes the 3 EDBs in initial acceptance.
5. All SCMs, public or private, are inspected on an annual basis regardless of when they were installed.
6. Retrofitted – 0, Facilities Inspected – 102, Facilities Maintained - 43

[2025 AR] MS4 Permittees