Lessons for Boulder in the wake of Hurricane Harvey

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Wikimedia Commons/Eric Hamiter

Historically, the Houston area has experienced many devastating storms. By the 1980s, public officials understood the critical value of the wetlands and prairies, long since paved over, in mitigating the effects of storms. Since then, scientists have warned that climate change will cause ever more frequent and more intense storms along the Gulf Coast. Yet Houston kept growing and more disastrous storms kept coming.

Parallels to Boulder

Boulder has some of the highest risk for flooding due to its location at the mouth of several canyons and because of development in its floodplain. As Boulder considers annexing (a precursor to development) the Hogan Pancost and CU South parcels into the City, it would be wise to consider the parallels with Houston.

CU South

Since Boulder’s 2013 flood, the City and CU have developed a flood mitigation concept at the South campus. Mitigation Option D plans for a 100-year flood event by constructing a dam along US-36 with flood detention behind it. But it is unclear from the information presented to City officials and the public if Option D offers the best cost/benefit and whether other mitigation options not explored might provide better flood protection at a lower cost, when considering the $40 million-plus cost for all three phases of the South Boulder Creek (SBC) flood mitigation plan. The Water Resources Advisory Board (WRAB) evaluated a box of options presented to them by City staff, but didn’t explore outside of that box — WRAB never questioned whether the 100-year event is even the appropriate event to design for versus 200- or 500-year events. 

In the context of climate change predictions and available literature such as the Association of State Floodplain Managers (ASFPM) 2011 recommendations and FEMA’s 2013 Climate Change Report, this was a surprisingly passive approach.

Hogan Pancost

Residents surrounding this parcel are very concerned about flooding — it has flooded multiple times in the past 100 years. Over the past 25 years, significant changes to the vicinity that affect the area’s hydrology have been made including development in an area previously designated for flood detention as part of the SBC flood mitigation design.

However, the FEMA flood maps haven’t been updated to reflect all of these changes.

Further, the water table in this parcel is just beneath the ground surface.  But, Boulder doesn’t manage, track or regulate groundwater, so its impacts and changes to the hydrology resulting from development are unknown.

Like the prairie surrounding Houston, Hogan Pancost provides flood buffering for the surrounding area, absorbing flood waters and protecting that area. More than 50 percent of the parcel is in the 500- or 100-year floodplain and approximately 50 percent of the acreage in surrounding neighborhoods is too.

However, these historical risk designations don’t reflect the reality of climate change — New York City recently doubled its estimate of city residents living in the 100-year floodplain in 2050 to 800,000 people. By comparison, FEMA’s estimate, prior to Hurricane Sandy, was about 200,000 people. 

Like Houston, removal of flood buffering eliminates protection for people nearby. Consequently, many cities are considering restricting, or have already restricted, development within floodplains. After Iowa experienced devastating floods in 2008, Cedar Falls and Iowa City restricted new development within 500-year floodplains.

Climate change and policy concerns

FEMA predicts areas at risk of flooding in the U.S. could increase 45 percent by 2100, largely because of climate change. With flood risk on the rise, the flood insurance program (NFIP) will have to insure 80 percent more properties than it does today, and the average loss for each property could rise as much as 90 percent.

Cautions from state floodplains managers

When structures are built in high-risk areas, it is often done with inadequate adjustments for either the flood hazard that exists and certainly not for the flood hazard that will exist in the near future. Flood mapping does not reflect future conditions.

Land use decisions tend to be based on local short-term economic factors in the form of community growth and resultant increases in the local tax base.  Local communities gain the “benefits” of tax base growth but then “externalize” the costs incurred during and after a flood to others (via the national flood insurance program and FEMA assistance).

There are several critical elements that must be carefully considered before Boulder decides to allow development at the CU South, Hogan Pancost and other flood-prone parcels:

General: Address flood mitigation holistically. CU South, along with Hogan Pancost and other parcels, offer the opportunity for a chain of undeveloped and restored wetlands along South Boulder Creek that incrementally restore flood buffers that have been incrementally lost over time.

CU South: Conduct an economic cost/benefit analysis that includes all three phases of the South Boulder Creek flood mitigation plan and within that framework, evaluate alternatives to Option D not previously considered. While staff has stated that Option D provides a superior cost/benefit ratio, the consultant’s study contains “financial cost/benefit evaluations,” not economic cost/benefit evaluations. The distinction is financial evaluations aren’t holistic — they identify the costs to Boulder but externalize many of the costs to everyone else. Economic evaluations identify the true cost. 

In the context of climate change, reconsider whether the 100 year flood event is the appropriate basis of design for the dam.

Hogan Pancost: Incredibly, despite all the knowledge gained by floods and climate change predictions borne out by recent flood experiences, the Boulder Planning Board, in their August annexation hearing, recommended guiding principles for development that included filling in the 500-year floodplain. 

Where will that displaced water go?

Boulder must prohibit development in the 500-year floodplain, including filling in of the floodplain. It is irresponsible to put people at risk.  Development or annexation proposals for this parcel have been before the Planning Board seven times and never received recommendations for advancement, generally because of flooding concerns. In the face of climate change, for Boulder to allow development in, or filling of floodplains, is willful negligence. The Boulder Valley Comprehensive Plan CU South guiding principles preclude buildings in the 500-year floodplain; why would we promote buildings in other 500-year floodplains?

It is imperative that City Council decisions give priority to the public good, especially our health and safety.  City Council will hear the case for Hogan Pancost’s annexation in October. Contact them and help them do the responsible thing and vote no to annexation.

For reference material, visit boulderweekly.com/opinion

Leonard May is an architect and planner and former Boulder Planning Board member and has worked with extensively in international aid, development, disaster recovery and mitigation.

This opinion column does not necessarily reflect the views of Boulder Weekly.