CU South annexation: A primer

An aerial view of Boulder following the 2013 floods. (Via City of Boulder Flickr)

Saturday, April 17, 2021 (Updated Friday, July 23, 2021)

The stage has been set for the annexation of 308 acres that may eventually become a southern campus for the University of Colorado. A final agreement between CU and city has been reached, votes have been scheduled, and party lines drawn over the largest addition of land in recent history.

It’s been a long and difficult process — CU first bought the land 25 years ago — with much opposition. Even now, a competing ballot measure will be before voters in the fall (though city officials say it will be irrelevant if annexation happens before November).

Ahead of September’s public hearing and vote, a beginner-level breakdown of how (and why) Boulder got here in the first place, as well as what’s ahead.

What does annexation mean?

Being added to the city so that services (water, sewer, etc.) can be accessed. 

Why is CU annexing?

So they can build out a southern campus: That’s been the plan since CU bought the land — a former gravel mine — in 1996. 

Why is the city interested in annexing?

Boulder wants to build a flood mitigation project there. CU is giving the city 36 acres of land to build a dam and detention pond — for free — in exchange for being annexed, as well as 44 acres of open space at no cost.

Why are we doing flood mitigation here?

The South Boulder Creek Major Drainageway Plan (also referred to as South Boulder Creek Master Plan, or SBC Master Plan), completed in 2015, identified the area near U.S. 36 as the best place for a dam and detention area. In fact, CU had twice (2000, 2006) requested that Boulder take the first step in an eventual annexation process — changes to the Boulder Valley Comprehensive Plan — for its land, but the city declined until a flood study of South Boulder Creek could be completed. 

This area was chosen because it offers the widest protection: 2,300 residents, 1,100 homes and 260 other buildings will be saved from future flooding by the current mitigation plan. It also makes sense given South Boulder Creek’s history of flooding: six times over the past 80 years (1938, 1951, 1952 and 1957, 1969 and 2013) with U.S. 36 being topped by flood waters twice (1969 and 2013).

The results of the SBC Master Plan were accepted by city council on Aug. 4, 2015, and ever since, flood mitigation here has been the goal.

Why is this annexation different from other annexations?

Its size: It’s the largest undeveloped piece of land to be added to the city in at least 30 years, according to staff.

Also, CU is a state entity, meaning it doesn’t have to abide by the city’s rules for development (design, density, height limit, etc.) That means any and all rules for future development need to be laid out in the annexation agreement in order for Boulder to have any say in what gets built there. 

CU has agreed to many conditions, such as abiding by Boulder’s 55-foot height limit for buildings, housing as the predominant use and decreasing heights on the edge of campus adjacent to existing neighborhoods. The university has also released high-level design guidelines: Buildings will be “clustered, village-style”; academic facilities will be under 175,000 square feet and “human scale”; any sports fields will have capacity of fewer than 3,000 people (so, no football stadiums or basketball arenas).

Read: What’s in the final agreement

But the plans don’t get as granular as the city normal requires during annexations. CU has argued that it won’t know exactly what will go there until it completes a multi-year planning process.

The city will be able to review and comment on the Campus Master Plan, CU South Master Plan and conceptual development plans for CU South. The earliest anything would be built there would be 2026, in line with construction start for flood mitigation.

In fact, the city has some safeguards to ensure CU can’t develop the land unless flood protection plans are approved. An option to de-annex the land if permitting fails is included in the final agreement, as well as a right of first refusal to guard against CU selling the property to someone else. As with all annexation agreements, any condition imposed on CU will transfer to a new owner if the city doesn’t buy it first.

Other reasons this is a big deal

Some neighbors and residents are concerned about development and all its attendant issues: traffic, noise, growing student population, etc. Additionally, CU has allowed public access to the land for decades. It has become quite popular as an off-leash dog-walking spot; many lament the loss of an amenity they’ve grown used to having, even if the property was always intended for development.

Public access to the campus will be preserved, per annexation terms. CU will provide a dog park and running track, both Boulder requests. And more than half the property will be open space of some sort,* owned either by the city or CU.
(*Like most CU South issues, it’s complicated. See more below under What is Boulder getting?)

What will be built there?

1,100 housing units, give or take a few. The final amount will depend on traffic studies: CU has agreed to a “trip cap.” The number of vehicles driving in and out of the site will have to stay under a certain amount. If analysis reveals that 1,100 housing units (or a certain amount of classroom space) would create trips over that limit, development would be adjusted accordingly to stay under the cap.

Per the agreement, housing will NOT be for freshmen or fraternities/sororities. The current breakdown for building is:

  • 550 apartment/condo units for faculty, staff, and graduate student housing
  • 550 graduate student apartment units (assume 2 bedrooms on average)
  • 500,000 square feet of floor area of academic facilities
  • Recreation facilities/athletic fields (such as tennis courts, which exist on the site today, or the aforementioned running track)

Townhomes or even single-family homes may be built on the edge of the property closest to existing neighborhoods, according to annexation documents: “Detached single family residential may be used as part of a strategy for transitions to adjoining areas.”

CU has also agreed that housing will be the predominant use of the site — given the extreme need for housing in Boulder — and that 150 dwellings will be built before anything else. Five acres will also be set aside for affordable housing, available to the broader community.

How much traffic are we talking?

There will be two main accesses to the site. CU has agreed to no more than 5,550 daily trips on South Loop Drive and no more than 750 daily trips on State Highway 93. There will be bike, pedestrian and transit access from Tantra Drive, available for emergency vehicles if necessary.

CU will be held to those numbers. The university will monitor all vehicle trips and issue regular to reports to the city. Any traffic over and above agreed-upon limits would have to be mitigated; CU would have 90 days to do so. There’s even a limit on the number of special events that can be held at the campus and add more traffic: 12 days per year.

Map of proposed CU South campus, open space (City of Boulder0

What is Boulder getting?

CU has committed to 82 acres, free to Boulder: 36 for flood detention, 44 of open space and 2 for a future fire station/public safety facility. Estimated value: $2.24 million (According to the city; when asked for its valuation, CU spokesperson Joshua Lindenstein wrote, “We are working to determine current values.”)

Boulder also has the option to purchase additional open space at a cost of $37,500 per acre, three years after annexation. If the city does not choose to buy the land, the university will build solar or community gardens there. Since the acreage is designated as Open Space – Other, it can’t be developed the way other parts of the site can.

If the land is purchased by Boulder, the primary objective would be restoration and/or preservation. There are two sensitive species in the area: Ute Ladies’ Tresses orchids and the Preble’s Meadow Jumping Mouse.

The university will transfer to the city its water rights associated with Dry Creek Ditch No. 2. In exchange, it will get a break on some city fees.

What is Boulder giving?

A portion of the flood mitigation costs are actually going to CU. In addition to the $41 million cost for flood mitigation,* $5 million would be used to reimburse the university for impacts to existing facilities and pay for fill dirt to prepare the land for development.

Reimbursing property owners for utilities projects (of which flood control is one) is standard practice, staff have previously testified. Paying for fill dirt may go above and beyond that, though it has been part of the plan for years, according to documents.

“The concept for soil fill was first recommended in the South Boulder Creek Flood Major Drainageway Plan (accepted by City Council in 2015),” the CU South Briefing Book states. “In recognition of multiple property interests related to the project, the recommended flood concept was developed to combine ‘excavation and fill to produce a configuration that minimizes the impacts to open space land and CU Boulder’s land.’ In other words, the recommended plan needed to be acceptable to all the various property interests, including CU Boulder (the landowner). In practice, the soil fill area will provide land that CU Boulder has stated is required for its development.”

*Though the costs to CU will likely stay somewhat constant, the cost of flood mitigation could increase by as much as 50%, consultants and staff have repeatedly testified.

Other considerations

What Boulder will do for flood mitigation if it can’t build here is unclear. Council members asked this question at two different points in 2019; staff responded that other options were initially analyzed but rejected in 2015 when council accepted recommendations of the South Boulder Creek Master Plan.

Loss of this property would likely send the city back to pre-2015 options, restarting the process of identifying (and possibly acquiring) an appropriate site, designing and then narrowing designs. There’s also the possibility that the current design will not be permitted by any one of the dozen agencies with say-so. In that case, further revisions to the design — and annexation agreement — may be needed.

When will a decision be made on annexation?

A public hearing and vote are tentatively scheduled for September, with final dates TBD. An online survey to solicit public feedback will be open through August 13.

Author’s note: This article has been updated to reflect the final version of the annexation agreement.

— Shay Castle,, @shayshinecastle

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