To learn more about USGS’ role providing science to decision makers before, during and after #Florence, visit the #USGS Hurricane Florence page at https://www.usgs.gov/florence
The floodwaters that covered wide swaths of the Carolinas’ coastal plain are finally receding, more than two weeks after Hurricane Florence made landfall Sept. 14 near Wrightsville Beach, North Carolina, and U.S. Geological Survey hydrographers are moving in rapidly to the areas where the flooding lingered longest. About 30 flood experts are in the second week of a high water mark campaign, traveling from one hard-hit community to the next, searching neighborhood by neighborhood and sometimes door to door for physical evidence of flooding.
The USGS experts are looking for telltale lines of seeds, leaves, grass blades and other debris left behind on buildings, bridges, other structures and even tree trunks as floodwaters recede. Once they find these high water marks, they label them, photograph them, survey them, and record crucial details about them.
The USGS flood experts’ field work is highly skilled and time-sensitive, because high water marks can be obliterated by weather and by property owners’ cleanup efforts. Hydrographers have been in the field collecting high water marks each day since Sept. 18, working mostly in two-person teams and moving as quickly as receding waters and the scope of the work permits. The teams from the USGS South Atlantic Water Science Center, which covers the Carolinas and Georgia, have recorded more than 600 high water marks in North and South Carolina and surveyed at least 365 of those. Field crews expect to record many more as they move into communities like Conway, South Carolina, where the floodwaters have not yet finished their retreat. You can see some preliminary results of their work at the USGS Flood Event Viewer for Hurricane Florence: https://stn.wim.usgs.gov/FEV/#FlorenceSep2018
Why is this fieldwork important? The physical signs of flooding provide valuable information that can confirm or correct other lines of evidence. Among these are measurements from a network of about 475 permanent and temporary river and streamgages that were in place in North and South Carolina when Florence struck; more than 175 stream and river flow measurements taken by field crews after the storm on flood-swollen rivers, streams and even roads; satellite photos and imagery from unmanned aerial vehicles (or drones); and computer modelled flood projections. Taken together, all this evidence will allow USGS experts to reconstruct precisely where, when, at what depth, and in what volume floodwaters inundated the region.
Right after the storm, the USGS’ early information from high water marks can help emergency managers decide where to locate relief centers, so that aid can reach the most severely affected communities quickly, and can help the U.S. Army Corps of Engineers manage flood control.
In the coming weeks USGS flood information can help the Federal Emergency Management Agency to discern the difference between wind and water damage – important information for property owners and insurers. Over the long term, it can help emergency managers plan better for future floods; improve the computer models used by the National Weather Service to forecast flooding; and provide information used by FEMA to update the nationwide flood zone maps that underpin the federal flood insurance program.
“I am proud of the USGS staff’s speed, thoroughness and accuracy as they do this essential work in difficult conditions, and under the pressure of time,” said USGS South Atlantic Water Science Center director Eric Strom. “The team began working well before Florence made landfall, when field crews began installing storm-tide sensors along the coast. Right after the storm passed, we mobilized as many as 60 people at a time to fix or relocate streamgages that were damaged or destroyed, monitor the flooding, and work with forecasters and emergency managers to get them the up-to-date flood information they needed. And now, because the rivers have receded so slowly, we’re in the midst of a long high water mark campaign in two states.
“It’s been a sustained, coordinated effort in response to a hurricane that triggered record-setting floods.”
Preliminary USGS data indicates that Florence’s heavy rains resulted in 19 water level records on rivers and streams in North Carolina and 10 records in South Carolina. Rivers that reached or exceeded the major flood stage heights forecast by the National Weather Service included the Cape Fear, Northeast Cape Fear, Neuse, Lumber, Waccamaw, Pee Dee, Little Pee Dee, Black and Lynches rivers.
The flooding in the Carolinas was long-lasting, with several rivers experiencing two peaks of high water flow or flood stage. The first one happened as local rainfall flowed into rivers and streams, and the second one came as rain that fell near the rivers’ headwaters worked its way downstream. In Goldsboro, North Carolina, about 100 miles inland from Florence’s landfall, the Neuse River escaped from its banks, crested at 27.6 feet on September 18, and lingered above the 18-foot flood stage mark for almost a week. The last two rivers to peak were both in South Carolina: the Little Pee Dee on Sept. 25 and the Waccamaw River on Sept. 26.
“Unfortunately, our experience dating back to the 1940s shows that the Carolina coastal plain is a flood-prone region,” said the center’s South Carolina-based associate director John Shelton, who was the on-site coordinator for much of the USGS response. “The scientific knowledge we’re gaining now will be put to good use helping to protect lives and property if and when floods strike this area again.”
For more than 125 years, the USGS has monitored flow in selected streams and rivers across the U.S. The information is routinely used for water supply and management, monitoring floods and droughts, bridge and road design, determination of flood risk and for many recreational activities.
Using dynamic forecasting models, climate scientists like Andreas Prein are looking at how intense rainstorms are changing over the coming decades.
Prein, a climate modeling scientist at the National Center for Atmospheric Research in Boulder, said warmer climates are leading to more frequent heavy rainfalls. Since 1950, the number of three-inch rainfalls in a day has increased about 25 percent across the U.S., according to Chad Gimmestad, senior forecaster for the National Weather Service Office in Boulder. Prein explained that the warmer air holds more moisture, so when rain falls more water is dumped than normal in cooler conditions.
“We have stronger evaporation over the ocean because it’s warmer, and then this moisture is transported over the continent,” Prein said. “It is basically exactly what happened in 2013 during the Colorado flood.”
Looking at the regional trends, Gimmestad said the heaviest two rainfalls expected in a year have increased about 10 to 20 percent in the western U.S. In Colorado, where there were once a two-and-a-quarter inch rainfalls, forecasters see two-and-a-half inch rainfalls, he said. While that increase isn’t as large as it is in the eastern U.S., where the heaviest rainfalls in a year have increased from 30 to 60 percent, it still has a significant effect.
“That’s when your flood occurs, so you just made your flood 10 percent bigger,” Gimmestad said..
Prein said the Front Range’s major flood events are often related to a stream of moisture from the Gulf of Mexico from the south traveling north along the mountains and turning west to create upslope flows. As the mountains push the moist air upwards, the heavy rainfalls are practically anchored by the mountains. Gimmestad, who commuted from Greeley to Boulder during the floods, said forecasters knew something big could happen from the weather patterns in 2013, but seeing it was something else. Gimmestad drove to Boulder on the night of Sept. 12, the second night of the heaviest rain during the flood. After about three hours of driving around, he found the one bridge still above the water over Boulder Creek. By the time he drove back to Greeley the morning of Sept. 13, he had to go out to Kersey because everything upstream on the Platte had flooded…
Laura Read, a water resources engineer at the National Center for Atmospheric Research, said the heavy rainfalls led to sustained flooding because of the Front Range’s relatively flat topography next to the steep gradient of the foothills. Residents in areas like Milliken didn’t see the flooding go down for as long as two weeks because the flood brought the groundwater table up, she explained. As the water came up from the ground from the 2013 flood, it caused additional damages to structures…
Brad Udall, senior water and climate research scientist at Colorado State University’s Colorado Water Institute, said scientists of just a few years ago were asking the wrong question about climate change’s effect on extreme weather events. Where scientists before framed the conversation about whether or not climate change caused extreme weather, they’re now looking at how it impacts these cyclical events.
“Climate change may not have caused them, but they add to their intensity. It adds to their frequency. It can add to their duration,” Udall said.
Scientists are still hashing out the degree to which climate change impacted the 2013 flood, Udall said. Heavier rainfalls, drier soils and growing risk for wildfires — which leads to more erosion, Read explained — are expected with the warming climates, experts said. Though there’s not yet enough data to definitively say whether these conditions will lead to more events like the 2013 flood, Udall said climate change is creating unprecedented weather events.
“We’re now in an era, because of climate change, where all the sudden our predictability has gone away,” he said. “We need to be prepared for really bad outcomes.”
The fast-moving water as a result of a storm system stalled over the Front Range inundated parts of Loveland, Lyons, Greeley and Boulder. Fort Collins saw little damage, though the flood temporarily impacted the ability to get in and out of the city.
Nine deaths were attributed to the flooding — two in Larimer County — and an estimated 2,000 homes were damaged or destroyed statewide, according to a Coloradoan report at the one-year anniversary of the flood. Parts of U.S. Highway 34 and other roadways were washed away.
The September 2013 flood ranks among the worst natural disasters in Colorado history, according to reporting during that time. The flood changed the landscape of Northern Colorado and led to years of rebuilding, including projects that just wrapped up this year.
The evidence can be seen in a new network of water gauges, a bolstered mass-notification system, and in the memories of residents five years after the 2013 flood rushed into Loveland. The wisdom will be useful if — more likely, when — another flood takes place in Larimer County.
“Floods are part of life here,” said Loveland Fire Rescue Authority Capt. Pat Mialy as she sat down with a 3-inch-thick binder titled “Flood Master Plan.” “Loveland is built at the bottom of a canyon; some things we can do nothing about, but we can help people become more prepared.”
Mialy, who is also Loveland’s emergency manager, said the city has an integral part in the Flood Master Plan, which encompasses the Big Thompson’s entire path through Larimer County, not just the flow at the mouth of the canyon.
Mialy said zooming out and viewing Loveland as a part of other communities marks one of the key differences between the 2013 flood and the next inevitable flood. After all, storms don’t care about ZIP codes.
“We’re listening to Estes Park, we’re listening to Glen Haven,” Mialy said, alluding to a network between agencies that have strengthened ties since 2013. “All our flood systems were integrated; they all speak to each other.”
A network of gauges and number crunchers watches over Loveland and other Larimer communities. The county’s floodplain administrator, Eric Tracy, said if there’s heavy water upstream, he knows about it.
Tracy told the Reporter-Herald that in the 2013 flood, waters washed away the only U.S. Geological Survey water level gauge monitoring flow through the Big Thompson Canyon, and with it, any doubts that the county needed better ways to watch the water.
“It was a very reactive approach before 2013,” Tracy said, motioning toward a pole-mounted camera at the U.S. 34 bridge near Sleepy Hollow Camp. He said the Colorado Department of Transportation uses it to get video footage of the bridge, but that means almost no upstream warning when a flood might overtake the road or worse, wash it away.
Tracy said that, ironically, he and many other flood plain administrators were in Steamboat Springs for a convention the day the 2013 flood ripped through Larimer County. He rushed back as fast as he could to handle the damage…
“The next six months were a nightmare,” Tracy said, noting that his cellphone was a nonstop stream of emergency notifications at that time.
Now, his cellphone still gives him notifications as water moves around the canyon, but he gets them hours before a flood event, when preventative measures can be ordered. Different monitoring locations are programmed with low-, medium- and high-priority warnings that all reach Tracy’s phone, as well as many other devices.
That’s because today, the bridge over Sleepy Hollow, among other locations, has some new gadgets.
“It’s a tipping cup,” Tracy said, now pointing to the top of a metal pole in the ground. He explained that the cup acts as a rain gauge: when it fills up to a certain amount, it tips over. It then counts the number of tips over time and transmits that data back to the county.
Also new is a water pressure transducer, which measures the depth of the water based on the pressure.
Another gadget, mounted on the side of the bridge, bounces sonar off the surface of the river to measure real-time water levels, Tracy said. Best of all, that sonar detector won’t wash away unless the bridge does.
The measurements mean numbers, and those numbers — in the hands of civil engineers such as Tracy — mean real-world information. Combining the data with a geomorphic map of the flood plain, and the county can figure out when and where flooding will occur.
Now, new rain and water flow gauges have been placed at several places in upstream Larimer. According to Tracy, water gauges exist at Sleepy Hollow Camp, Olympus Dam, Mary’s Lake Road, Fall River, Devil’s Gulch, Glen Haven and Drake, among others in rural water flow areas.
“The data will help the National Weather Service ground truth on what they see on their radar systems and will assist in the accurate execution of weather alerts for the Big Thompson basin,” Tracy said. ” The data will also be used in real time in the Emergency Operations Center for large flood events to assist emergency personnel and road and bridge crews in the field.”
Mialy said Loveland authorities are privy to the same information, and they can view it on a dashboard with other agencies.
Lori Hodges, director of Larimer County’s Office of Emergency Management, said the 2013 flood marked a large shift in the county’s emergency preparedness — it also marked a change in her career.
“What’s new since 2013?” Hodges reflected, “Well, my office didn’t exist in 2013. … I was hired because of the flood.”
Hodges said that day one on the job, she updated the county flood plan to reflect the Larimer County Sheriff’s Office’s request for a broader plans, both geographically and socially.
“Before it was a response-based program,” Hodges told the Reporter-Herald. “They needed to look more broadly at mitigation.”
Part of that mitigation means preparing the public for an emergency flood and keeping them away from danger areas.
Sometimes, preparedness is as simple as knowing your neighbors, Hodges said. In the wake of both the 2013 flood and the 2012 High Park Wildfire, both of which called for federal emergency aid, Larimer County created Larimer Connects, a program designed to bridge gaps between county residents.
According to the program’s website, Larimer County has had the most federally declared disasters in Colorado; the website goes on to say that with a track record like that, it’s necessary for Coloradans to expect the worst, especially in unincorporated areas such as Glen Haven and Red Feather Lakes, both of which have created emergency plans since previous disasters.
Larimer Connects offers assistance in creating community hubs such as the North 40 Mountain Alliance, a self-sustaining nonprofit group surrounding Red Feather Lakes.
“The one thing we really did learn from the flood is that when communities are more connected, the better they do when there was a flood,” Hodges said. “It’s social capital; that will cause people to recover faster and better.”
Larimer Connects intends to build resilience within communities by connecting them to resources and each other.
Hodges said that ironically, densely populated areas such as Loveland and Fort Collins have less social capital; neighbors aren’t as tight or reliant on one another, meaning disasters can cause even more disruption.
Everbridge over troubled waters
Mialy said agencies within the county have no problem notifying one another of impending floods — thanks to the new data network — but that’s not enough: Residents must also be aware.
Since the 2013 flood, Loveland has urged residents to sign up for the Larimer Emergency Telephone Authority LETA911 emergency notification system that alerts residents of oncoming or current dangers.
Mialy said the system works almost exactly like an Amber Alert, which automatically notifies all cellphones in a given area of an abduction or other threat.
The problem is, Larimer County doesn’t have the authority to push notifications unless residents sign up.
When signed up, the system uses Everbridge, a mass-notification system to show road closures, evacuation notices and other warnings to all registered devices.
Loveland Fire Rescue Authority emergency management specialist Lenny Layman said through that system, authorities can type a message and draw a polygon on a digital map. When they say “go,” that message is delivered to any and all devices set up within that polygon.
With this system, law enforcement or emergency responders notify the public of an incident before residents feel the need to call dispatch.
He said this could prove especially useful in the event of a flood, when authorities can figure out exactly which neighborhoods could end up underwater.
Users can set up for notifications at multiple addresses. For instance, parents can add their child’s school to the list so they can receive notifications even if they aren’t near an affected area.
Moreover, LETA911 can ping a multitude of channels, including email, landlines, pagers and cellphones using both calls and texts.
“The more information we can send, faster, the more lives saved,” Leyman said. “But you have to opt into Everbridge.”
Mialy said that in her eyes, Loveland has only become stronger since 2013, despite the fact that the city remains in disaster recovery mode.
“We can’t prevent natural disasters,” Mialy said. “But we can identify all our weaknesses.”
In the weeks leading up to September 2013, the Weld County Sheriff’s Office was in the midst of emergency preparedness training.
In a sense, they were ready when a slow-moving cold front stalled over Colorado on Sept. 9, dropping several inches of rain. By the 15th, there was widespread flooding across a 200-mile stretch of the Front Range, including as far south as Colorado Springs and as far north as Fort Collins. A state of emergency was declared in 14 counties, including Weld.
Although deputies were fresh off emergency preparedness training, Weld County Sheriff Steve Reams said the floods identified critical deficiencies in the county’s infrastructure, namely communications.
“That’s something you don’t see everyday,” Reams said. “You don’t think about potential communications problems when you’re working a normal day in law enforcement.”
Colorado’s shared statewide communications system for emergency responders, pushed for in the wake of the 1999 Columbine High School shooting and again following 9/11, was the first to go, Reams said. It became overloaded and essentially worthless as flooding affected Boulder County, then all of Larimer County and finally all of Weld County.
When deputies abandoned the statewide system, they moved to cell phones, their secondary mode of communication, Reams said. But callers from throughout the country trying to check in on loved ones clogged the towers. As a last resort, the sheriff’s office orchestrated a lot of its moves by text message.
“Obviously that’s not the best way to conduct business,” Reams said. “The county has since created its own radio infrastructure that allows us to operate on our own platform. The bandwidth in the county has never been better.”
In addition to coordinating emergency response, Reams said the department had issues connecting with off-duty deputies to get them to come into work. Each deputy now has their own county-issued cell phone, so they can be reached in a timely manner in the event of an emergency. The department has also established better employee tracking to know who is available, even officers who are off-duty.
“Everything came down to an ability to communicate,” Reams said. “Once one mode went down, we had to find another mode of communication. Then that went down.
“You can fix almost any problem as long as you have the ability to communicate about it.”
If communications issues weren’t enough, the 2013 floods also illustrated the sheriff’s office error in keeping almost all of its emergency equipment centralized in Greeley. As the South Platte River breached its banks, it damaged 122 bridges and more than 650 lane-miles of road.
“Every major north-south road with a river crossing was completely wiped out,” Reams said. “Balancing equipment needs was a huge challenge as trying to get equipment from the north part of the county to the south was impossible.”
The Sheriff’s Office has since made changes to where it stages emergency equipment throughout the county.
In the city things weren’t quite as chaotic, said Pete Morgan, current Greeley Fire Marshal and the city’s emergency manager at the time of the flood. Fortunately, Greeley had beefed up its public safety communications prior to the flood, including working with cellphone providers to establish priority access to its networks in the event of an emergency. The city has since increased the number of employees across a variety of departments who have priority access to those networks.
But Morgan said the floods did show the fire department’s Water Rescue Team, trained in underwater rescue operations, was not prepared for swift water rescue needs as a result of the flooding.
The department has since gone from zero swift water rescue technicians to 15, with another five set to get their certification in the next year. Every Greeley fire employee with a response job at least has their swift water operations certificate, which is one rung below a swift water rescue technician, Morgan said. The department also has two swift water rescue instructors to perform in-house certification training.
Every fire truck and ladder now carries equipment specific to swift water rescue.
“The benefit with the additional equipment and certifications is when a swift water call comes in, we don’t have to wait for the Water Rescue Team to gear up and come out to the scene,” Morgan said. “We can respond directly with any of our trucks and ladders to begin rescue measures.”
The city also created an Incident Response Team composed of Greeley’s police, fire, public works, water & sewer, public information, risk management, and information technology departments, among others. Representatives from each department meet and train regularly about how to coordinate response efforts.
A trial began Wednesday to determine whether the city of Colorado Springs violated clean water laws by discharging pollutants and large-volume water flows from its storm water into Fountain Creek and other Arkansas River tributaries.
The trial is for a 2016 lawsuit by federal and state.environmental agencies against Colorado Springs. The case is central to long-standing disputes that Pueblo County and the Lower Arkansas River Valley have with the city for defiling the creek and the river.
The environmental agencies contend the city is responsible for creating a threat to public health because the stormwaters increase levels of E. coli, pesticides and other pollutants into the creek.
The agencies also contend discharge of “extraordinary high levels of sediment impairs (the creek’s) ability to sustain aquatic life, damages downstream infrastructure and communities like Pueblo, worsen flood damage (and) impairs farmers’ ability to irrigate and obtain water to which they are legally entitled under Colorado law.”
Senior Judge Richard P. Match of U.S. District Court in Denver is presiding over the trial that is expected to run at least 10 days.
The Pueblo County Board of County Commissioners and the Lower Arkansas Water Conservancy District joined the U.S. Environmental Protection Agency and the Colorado Department of Health and Environment as plaintiffs by intervening in the case.
The district is comprised of Pueblo, Otero, Crowley, Bent and Prowers counties.
The lawsuit alleges that damage to the creek and river is caused because Colorado Springs’ stormwater system is inadequate, and for numerous years has violated clean water laws by exceeding discharge limits set in permits issued by the state for the system…
An attorney for the city, Steven Perfrement, defended the city’s efforts to operate the system, and to control discharges of pollutants and the volume of water flows. “The city has adopted programs and enforces them.”
The mine spill temporarily closed down recreation in the river and forced farmers to shut off irrigation to their crops. But life in the river? It didn’t change much. The bugs and fish survived and showed no signs of short-term harm. The fish had been living with heavy mineralization of the water for decades.
Crisis averted — until this year…
The Animas began the summer with record low water because of drought and a warm winter. That primed the nearby mountains for a big wildfire. The 416 Fire ended up burning about 55,000 acres around the drainage basin for Hermosa Creek, a tributary of the Animas. Now when it rains over the burn area, a thick sludge washes into the river.
Horn says official surveys haven’t been conducted, but it’s likely the first few ash-laden runoff events killed 100 percent of the fish in a 30 mile stretch of the river.
“You could literally see the fish coming to the banks gasping for air. It physically smothered their gills and their ability to breathe,” Horn says. “So there it was, it didn’t look as bad. It came from a, you could argue, natural source and did way more damage.”
Many western rivers are stressed. They’re pressured by drought, pollution, overuse by cities and farmers and runoff from wildfires. The Animas acts as the perfect poster child.
“It certainly is unlucky,” says Scott Roberts, a researcher with the Mountain Studies Institute, a non profit research group based in nearby Silverton. “It’s unlucky now. And it’s been unlucky for throughout time really.”
The river’s facing problems that show themselves, Roberts says, like a vibrant orange smear or a chocolate brown sludge. Or like earlier this summer when the river’s water all but disappeared within Durango’s city limits, recording its record lowest flow in 107 years of data.
But there are many others that don’t draw intense public attention. Before the Gold King Mine spill, and even now, the river receives acidic water laden with heavy metals from the region’s numerous abandoned mines. Adding insult to injury, in July 2018 a truck carrying waste material from the mine site crashed into Cement Creek, another Animas tributary.
“It’s being stressed by drought, being stressed by warmer temperatures. It’s being stressed by runoff from wildfires, being stressed by elevated metal concentrations, being stressed by bacteria, by nutrients,” he says.
Roberts points to studies that showed samples of the river’s water with high levels of bacteria commonly found in humans, likely leached from underground septic tanks.
“I don’t think that the problems that are plaguing the Animas today are unique to the Animas,” says Trout Unlimited’s Ty Churchwell, based in Durango…
In fact, Churchwell says, all these issues are increasingly common throughout the West. Drought, ash-laden runoff and mine pollution are often the norm in western watersheds. The Animas has just experienced the extremes of all three in a short period of time…
But it could be another five to ten years before the Animas is back to its former self, according to water quality specialist Barb Horn.
Old Denver pulsed with H2O, water that snaked through the creeks and irrigation canals crisscrossing Colorado’s high prairie before 150 years of urban development buried most of them or forced them into pipes.
New Denver wants those waterways back.
City leaders are ramping up what they describe as a massive, restorative “daylighting” of buried water channels wherever possible — cutting through pavement and re-engineering old streams and canals to create up to 20 miles of naturalistic riparian corridors. Hundreds of millions of dollars have been committed. Eventual costs are expected to top $1 billion over several decades. This work reflects increased interest worldwide in harnessing water and natural processes to make cities more livable.
Starting in 1858 with the discovery of gold in Colorado’s mountains, Denver developers focused on filling in creeks to make way for the construction of railroads, streets, smelters and housing — all laid out across a grid imposed on the natural landscape. The 184-page Green Infrastructure Implementation Strategy that Mayor Michael Hancock’s administration issued this summer reverses that approach with an inventory of high-priority projects aimed at — to the extent that booming growth and development will allow — reopening and revitalizing waterways.
“It is like undoing history,” project manager Patrick Riley said last week along a newly formed 1,000-foot stretch of Montclair Creek — already attracting geese as big trucks beeped and contractors in neon green vests re-contoured the urban terrain.
The Montclair Creek project marks Denver’s most ambitious and controversial daylighting so far, a $298 million revival of a waterway that flows 9 miles from high ground at Fairmount Cemetery (elevation 5,485 feet) under the north half of the city. Work crews are excavating and rerouting water, digging holes for ponds, and planting native grasses and perennials in four areas: the 130-acre City Park Golf Course, the Park Hill Golf Course, a 1.2-mile greenway along 39th Avenue, and a landscaped “outfall” through a 5-acre Globeville Landing park near the South Platte River (elevation 5,274 feet) west of the Denver Coliseum.
City engineers say that, by reconstructing the urban landscape where possible, they’ll slow down water, filter it through vegetation to remove contaminants, control storm runoff and nourish greenery to help residents endure the climate shift toward droughts and rising temperatures…
While a lack of open land and neighborhood resistance can limit daylighting of long-squelched creeks and canals, increasing volumes of storm runoff — the result of the paving of more and more of the city — require action.
The U.S. Army Corps of Engineers has supported daylighting, recognizing that pipes and concrete channels typically can’t handle surges the way natural creeks and floodplains once did before development…
Other projects in the works:
— Re-exposing a southern branch of Montclair Creek that flows under an area extending from City Park across Colorado Boulevard and eastward along Hale Parkway.
— A $77 million removal of concrete and widening of the Weir Gulch that runs through southwestern Denver from South Sheridan Boulevard to the South Platte River.
— A $26 million revitalization of Harvard Gulch in south-central Denver.
— The $249 million enhancement of the South Platte, reshaping and widening river banks between Sixth and 58th avenues, to create an ecosystem healthy enough for trout to reproduce through Denver.
— Converting portions of the 71-mile High Line Canal irrigation system, built in 1883 and owned by Denver Water, into a greenway and refuge.
— Other waterway projects that city officials are discussing involve naturalistic re-engineering of concrete trapezoidal channels in Montbello, flood-prone gullies in Globeville, the southwestern Sanderson Gulch, and buried channels citywide where alluvial sediment indicates creeks once flowed before settlers arrived.
Denver innovations include installing an ultraviolet water-cleaning station at the Montclair Creek outfall to boost natural processes in zapping chemical contaminants, an expanding array from antibiotics to antidepressants, before water reaches the South Platte.
Along Brighton Boulevard north of downtown, city crews also built 56 cement boxes, designed to hold native grasses and flowers in a replaceable soil mix that includes ground-up newspaper, to filter runoff water so that less pollution reaches the South Platte…
Dealing with floods by trying to funnel more and more runoff into culverts and pipelines has become increasingly costly and ineffective, city officials said. A recent city study estimated that dealing with worsening storms by installing more pipelines would cost taxpayers $1.4 billion.
But it’s unclear whether a new approach of embracing waterways will be cheaper in the long run.
As work crews neared completion of the Montclair Creek outfall by the South Platte, project manager Riley said recreational benefits and a need for places “where water could percolate out naturally” — rather than costs — are driving this push that has unified support from city leaders.
“You have to do what is right for the health of rivers. That’s part of the health of the city,” Riley said. “You are going to see a return to natural processes.”
According to the complaint filed this week, commissioners approved the floodway expansion over the resistance of local residents, who said the re-mapping would limit development on their private properties — some of which are functioning farms — and cause their flood insurance rates to skyrocket…
The re-drawing was performed by the Colorado Water Conservation Board, with assistance from Boulder County staff, and was approved last month 2-0 by commissioners. Commissioner Cindy Domenico was absent. When the change officially takes effect Oct. 1, it will substantially widen the floodway along portions of Lower Boulder Creek northwest of Erie.
A floodway is a narrow channel where, in the event of a flood, water will be flowing. A floodplain is where shallow water is likely to be during the event of a flood, though shallower and flowing at a lower volume, if at all, than water in a floodway.
The former, by definition of Boulder County’s standards, is more heavily regulated than a floodplain. Land regulated under floodway status is often limited to very specific redevelopment.
According to the complaint, plaintiffs’ efforts to have the hearing delayed to learn more about proposed expansion went unheeded…
The Colorado Water Conservation Board in 2015 changed the definition of a floodway, triggering a review of flood-hazard areas across the state. Wheeler Open Space, however, was not reassessed, given the lack of residential buildings on the land, Boulder County Senior Assistant Attorney Kate Burke said earlier this year.
In light of the planned oil and gas development on the site, a modeling with the new standards was performed. Under the new guidelines, the entirety of well site Section 1, which is in the open space, is within a floodway, according to documents Boulder County submitted in mid-April with its formal comments to the Colorado Oil and Gas Conservation Commission.