Colorado State University
OP-23: Rainwater Management

CSU’s Low Impact Development (LID) practices include incorporating permanent stormwater control measures, detention and treatment for stormwater pollution prevention in each project to the maximum extent practicable. Although Colorado water law imposes restrictions on the amount of LID we can incorporate (rainwater harvesting is illegal in Colorado except where a residential parcel has a domestic water well, or a legal water augmentation plan is established), CSU incorporates LID methods that infiltrate stormwater whenever a site is redeveloped (e.g. a building is constructed in a former parking lot location), and whenever a new building is constructed in a formerly undeveloped area. Our landscape architects design surface drainage features that are pleasing, convey stormwater through native plantings and enhance infiltration. New buildings typically incorporate swales, and plantings that receive and use the stormwater, rather than connecting roof drains directly to subsurface storm sewers. Where feasible, landscaping and hardscape are configured to minimize directly connected impervious areas; this helps reduce unnecessary impervious areas and routes stormwater from impervious surfaces over permeable areas to slow runoff and increase infiltration. CSU has an MS4 permit issued by the Colorado Department of Public Health and Environment, the plan for which includes a provision to review and incorporate permanent stormwater controls with new and redeveloped parcels. Examples of CSU’s LID implementation at its Fort Collins campuses include the following: • At least 29 detention/extended detention ponds • More than 30,000 square feet of permeable pavers • At least 10 bioswales • More than 10 bioretention/rain garden systems • Several constructed wetlands • A green roof • A 3,700 square feet BMP demonstration area with five different LID features including rain gardens and permeable surfaces

CSU has a stormwater permit that regulates what measures the university must take and what is to be done to minimize storm water pollution. It is structured with six "Minimum Measures," each of which has multiple goals and requirements. Discharges of process wastewater or contaminated water are not allowed to go to storm drains. In some cases, a specific discharge permit with effluent limits can be obtained to allow discharge of sump pump discharges. However, these permits require monitoring, reporting and may require treatment to meet the discharge limits. CSU's storm water and surface water discharges are regulated by the Colorado Department of Public Health and Environment (CDPHE). In 2018, CSU developed a Stormwater Quality Standard that requires that stormwater treatment is included with every project.