Stormwater Management


Stormwater Management

Controlling flooding and protecting our environment. 

What's New

Castle Pines has new Standard Notes and Details, both full size and 11 x 17, checklists, as well as a Low Impact GESC Application and Checklist. In addition, the City has new guidance documents on post-construction stormwater management in both new developments and redevelopments.


What is Stormwater?

Stormwater is rain or snowmelt that falls on streets, parking areas, rooftops and other developed land and is not absorbed into the ground. As the stormwater flows over driveways, lawns and sidewalks, it picks up debris, chemicals and other pollutants. The stormwater either flows directly into nearby bodies of water or travels through the drainage systems to get there. Storm drains are not part of the sewer system, so water in storm drains is not treated before entering streams, rivers or lakes.

By managing stormwater, communities are better able to protect our environment, reduce flooding, support healthier streams and rivers, and create healthier, more sustainable communities.

How Does Castle Pines Manage Stormwater?

The City of Castle Pines is committed to maintaining a proactive stormwater management program to improve the quality of runoff entering the storm drain system and receiving streams. The program plays a critical role in controlling flooding, enhancing safety, protecting the environment and meeting the requirements of federal environmental regulations.

Castle Pines holds an Environmental Protection Agency Municipal Separate Storm Sewer System (MS4) permit, which requires the City to monitor, maintain and control its stormwater facilities. Stormwater must be managed for the good of the entire community, because water runoff does not follow subdivision or community boundaries. The City is responsible for the repair and maintenance of existing stormwater facilities as well as the construction of needed capital improvement projects related to the stormwater system.

City responsibilities include:

  • Administering the MS4 stormwater permit for the City to include inspection services, reporting, and annual report to the CDPHE
  • Maintaining stormwater infrastructure
  • Administering criteria and best management practices identified in the stormwater manual
  • Maintaining membership in professional stormwater organizations and provide public informational advertisements in the local newspaper as required under the MS4 permit
  • Performing development review of stormwater plans for private development
  • Providing the Program Description Document (PDD) for review and comment upon request. (Please contact the Public Works Director at

Grading, Erosion, and Sediment Control (GESC) Permit

GESC application, submittal materials and permits must cover all construction activities associated with the project from the initial earth work to final stabilization.  Overlot grading only permits will only cover overlot grading and site stabilization. A modification would be required for overlot grading permits to perform any construction outside of overlot grading activities (e.g.vertical or infrastructure construction). The GESC Checklist and Low Impact GESC Checklist are intended for all work from initial earth work through final stabilization and not all items may be applicable to every project.

To apply for a GESC permit, complete the following documents:

  1. GESC Application or Low Impact GESC Application (GESC if an acre or greater (≥1 acre) and Low Impact GESC if under an acre (<1) and not part of a common plan of development)
  2. GESC Checklist or Low Impact GESC Checklist
  3. Submittal materials required by the checklist (typically GESC plans and report – a stormwater management plan may be substituted for a GESC report)
  4. Cost Opinion Estimate
  5. A copy of the Colorado Discharge Permit System (CDPS) General Permit for Stormwater Discharges Associated with Construction Activities (if applicable)
  6. Post-Construction NDRD Checklist
  7. Drainage Report (GESC) or Letter (Low Impact GESC)
  8. Submittal materials regarding the permanent control measures
  9. Copy of CDPS General Permit for Stormwater Discharges Associated with Construction Activities (for project disturbing an acre or more)

Submit using the City's SmartGov permitting portal  *A 2.95% credit card transaction fee will be applied

If you have any questions, please reach out to Jay Rowe at

All applicable permit fees will be paid through SmartGov. Letters of credit may be submitted to the City's offices, located at 360 Village Square Lane, Suite B, Castle Pines, CO 80108.

City staff and their consultants will review your application and submittal materials and provide comments as necessary. The GESC plans and report will not be approved until it meets the City’s Stormwater Program requirements and may require resubmittals. Resubmittals require a comment and response letter from the applicant or their consultants.

GESC Review Timeline

GESC Submittal* Castle Pines Review Timeline
Complete 1st submittal 3 weeks
2nd submittal 3 weeks
Subsequent submittals 3 weeks
Signature set 1 week
Modifications 1-3 weeks depending on extent of changes

*Projects located in the Cherry Creek Reservoir Basin may have longer review times depending on referrals to Cherry Creek Basin Water Quality Authority (CCBWQA). 

Permit fees will be assessed during the GESC review and provided to the applicant.  Fees may be paid at the City's offices after the application and submittal are accepted. Letter of credit or other acceptable Fiscal Security must be submitted to the City at their offices.

After acceptation and receipt of fee payment, the applicant will receive an email to schedule the initial inspection of control measures.

After the initial inspection approval, the permit will be issued and emailed to the applicant.

Note: No clearing, grubbing, earthwork or construction may occur prior to the initial inspections other than work to install temporary control measures.

Keep Stormwater Clean!

We can all do our part to keep the stormwater in Castle Pines clean! Here are some simple tips to help ensure that pollutants don't contaminate nearby bodies of water:

  • Use chemical fertilizers and pesticides sparingly. Sprinklers and rain wash chemicals into nearby storm drains and eventually into area streams and lakes. Even lawn clippings contain pollutants. Leave clippings on the lawn as natural fertilizer or compost them.
  • Clean up after pets. Pet waste contains pollutants that can contaminate surface water.
  • Wash cars at commercial car washes instead of at home in your driveway. The water you used to wash your car in the driveway drains to creeks and other surface water.
  • Prevent dripping and spilling of automotive fluids. Repair leaks and recycle oil, antifreeze and other fluids.
  • Properly dispose of paints, solvents, used oil, cleaning products and other hazardous household wastes.

Floodplain Permitting

Construction projects located in or under FEMA -regulated floodplains require a floodplain permit. The permit should be uploaded to SmartGov with the other GESC submittal documents.

Nutrient Pollution

Nutrient pollution is one of America's most widespread, costly and challenging environmental problems, and is caused by excess nitrogen and phosphorus in the air and water. Too much nitrogen and phosphorus in the water causes algae to grow faster than ecosystems can handle. There are several things residents can do to reduce the potential of nutrients getting in to our waterways. For more information view a helpful brochure produced by the Colorado Stormwater Council.

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Douglas County Household Chemical Waste Roundup

Hosted by the Tri-County Health Department, bring your household chemicals, oils and batteries to any of the three Chemical Roundups that take place throughout Douglas County annually. These are open to all residents of Douglas County, so proof of residency (such as a driver's license or utility bill) is required. Cost is $25 per vehicle.

View the annual Roundup schedule online.

Accepted items include:

  • House, garden and pool chemicals
  • Automotive Fluids
  • Fuels
  • Propane tanks (1-20 lbs.)
  • Aerosol cans
  • Ammunition
  • Passenger vehicle and truck tires (removed from rim)
  • Vehicle and household batteries
  • Paint and paint products
  • CFL and fluorescent light bulbs

Illicit Discharges and Reporting

Castle Pines detects and eliminates pollution from entering the City storm drains as part of the illicit discharges and stormwater quality requirements ordinance.

Residents and visitors can help by pollution entering storm drains and waterways.

Things to look for include:

  • An unusual color of the water
  • An unusual or foul odor
  • Suds or puddles when there has not been recent precipitation
  • Any unusual-looking substance leaving the storm drain
  • Illegal dumping of waste near storm drains (e.g., household chemicals, automobile fluids)
  • A large number of dead or dying animals including fish, crayfish, insects, waterfowl or other animals near a waterbody

To report a concern or spill contact the Public Works Director


Larry Nimmo

Public Works Director