Boulder County officials see 2016 flood-recovery expenses approaching $76.8M — Boulder Daily Camera

Storm pattern over Colorado September 2013 -- Graphic/NWS via USA Today
Storm pattern over Colorado September 2013 — Graphic/NWS via USA Today

From the Boulder Daily Camera (John Fryar):

Ongoing or in-the-pipeline projects could cost as much as $76.8 million in 2016. Most of these projects are aimed at repairing the September 2013 floods’ damages to county roads, bridges, parks, open space areas — as well as services and programs to assist Boulder County residents and property owners still recovering from the floods.

That estimate, from a recent county staff report to the Board of County Commissioners, would be on top of more than two years of flood recovery spending that’s expected to have totaled nearly $97.9 million by the end of this year.

And 2016 won’t be the final year that county officials expect to devote a major portion of their spending on flood recovery.

The county staff is sticking by its late 2013 estimates that flood recovery projects and services will have a total cost of more than $217 million by the time they are completed, so another $43.2 million might be needed beyond 2016.

EPA doesn’t expect ‘adverse effects’ from Boulder County mine discharge — Longmont Times-Call

The Arcade Saloon in 1898 Eldora Colorado via WikiPedia
The Arcade Saloon in 1898 Eldora Colorado via WikiPedia

From the Longmont Times-Call (John Bear):

EPA spokeswoman Laura Williams said the agency is continuing to investigate samples taken from the creek to see whether the metal content in the water is higher than historic levels.

Officials said that samples collected did not show the presence of some of the metals the EPA tests for, but, as of Monday, they had not explained what metals were present in the samples and in what concentration.

The tests look for aluminum, antimony, arsenic, barium, beryllium, cadmium, calcium, chromium, cobalt, copper, iron, lead, manganese, magnesium, nickel, potassium, selenium, silver, sodium, thallium, vanadium and zinc.

The deluge of water from the Swathmore Mine on Sept. 21 temporarily turned the creek orange and led officials to briefly shut down water intake systems downstream.

Boulder and Nederland use the creek as part of their water supplies.

EPA officials said soon after the spill that the discharge from the mine was not toxic, but sent water samples for testing. They expect further results to be available later this week.

Todd Hartman, a spokesman for the Colorado Department of Natural Resources, said the mine has discharged at a “low flow rate,” less than 15 gallons a minute, for as long as the landowner can remember, but had apparently never surged before…

The Colorado Division of Reclamation, Mining and Safety has identified six old or abandoned mining sites in the county that impact water quality or likely do: Bueno, Emmett, Evening Star, Fairday, Captain Jack and Golden Age.

Four of the mines — Bueno, Emmett, Evening Star and Fairday — likely impact water quality, but currently have no active water treatment programs, records show.

Hartman said the six mines are designated as “legacy mines” because they were mined prior to modern mining reclamation laws that came into effect in the 1970s.

The Captain Jack Mill is designated as a Superfund site because of multiple contaminants, including lead, arsenic and thallium, along with several other heavy metals, according to the EPA.

Mary Boardman, a project manager with the Colorado Department of Public Health and Environment, said the Captain Jack Mill Superfund Site was added to the national priorities list in 2003 and a decision was made to begin clean-up in 2008. That project remains ongoing.

Hartman said the Golden Age Mine is still in the investigative stage, so officials can determine the best approach to managing it.

Boulder County has several waterways deemed “mine related impaired streams” and one state-run “nonpoint source mine reclamation project” that includes removing mine tailings, waste piles and restoring streams, according to the Colorado Division of Reclamation, Mining and Safety.

Hartman said “mining impacted” means the streams have been degraded by acidity or metals from a combination of mining sources and natural background geological sources in such a way that they fall below Clean Water Act Standards.

He said it’s difficult to determine how many old or abandoned mines are in Boulder County, but nearly 1,200 safety closures have been conducted in the last 25 years, and the owner of Swathmore Mine has asked that one be installed by the Colorado Division of Reclamation, Mining and Safety.

“Those are grates and other measures to prevent people and animals from entering (or) falling into old mines,” Hartman said.

@OmahaUSACE to begin ecosystem restoration project along Lower Boulder Creek

Lower Boulder Creek Restoration site map via Boulder County Open Space
Lower Boulder Creek Restoration site map via Boulder County Open Space

Here’s the release from the US Army Corps of Engineers (Omaha District):

The U.S. Army Corps of Engineers, Omaha District, in partnership with the Boulder County Parks and Open Space Department, will hold a groundbreaking ceremony to celebrate the start of construction of an ecosystem restoration project along an approximately one-mile stretch of Lower Boulder Creek. The ceremony will take place on Thursday, October 8, starting at 12:30 p.m. MDT at the project site, which is located between N 109th Street and Kenosha Road in Boulder County approximately 3.5 miles west of the Boulder County-Weld County line and 8 miles east of the city of Boulder. Limited parking will be available along the Boulder County property access road located just east of the 109th Street Bridge. See attached map. In case of inclement weather, the ceremony will take place at the Goodhue Farmhouse located at the Carolyn Holmberg Preserve, 2009 S. 112th Street, Broomfield, Colorado.

BACKGROUND: Lower Boulder Creek once meandered across a broad floodplain that supported numerous wetlands, streamside vegetation, and associated native fish and wildlife populations. Since European settlement, the project reach and its associated habitats have been dramatically degraded by activities including upstream development, water diversions, pollution, non-native species, and gravel mining. During past on-site mining activities, the project reach of Lower Boulder Creek was channelized, and earthen levees were constructed along portions of its banks, thus disconnecting the channel from its historic floodplain and creating an impoverished stream and riparian environment. The project area is currently in a highly degraded state, which without active ecological restoration would take decades or longer to improve.

In 2011, the Omaha District completed a feasibility study which identified a feasible project to restore habitat for migratory birds and other wildlife, restore wetland and stream values, reduce invasive species and provide other ecosystem improvements. A construction contract was awarded to American West Construction LLC of Denver, Colo. for $2.6 million, which includes realigning the one-mile section of Lower Boulder Creek to restore natural meanders, in-stream habitat, and the creek’s floodplain and planting native riparian, wetland, and upland grasses, forbs, trees and shrubs along the stream and within the floodplain to greatly improve wildlife habitat. The project is expected to be complete by Fall 2016.

Click here to go to the Boulder County Open Space website for all the inside skinny.

Testing continues on Eldora mine seepage, but officials say spill isn’t toxic — Longmont Times-Call

The Arcade Saloon in 1898 Eldora Colorado via WikiPedia
The Arcade Saloon in 1898 Eldora Colorado via WikiPedia

From the Longmont Times-Call (John Bear):

Officials believe 4,500 gallons of orange water that leaked from an old Eldora-area mine into a creek Monday — prompting the shutdown of water intake systems downstream — is not toxic, but they’re still awaiting further test results.

Environmental Protection Agency spokeswoman Lisa McClain-Vanderpool said Tuesday that the agency collected water samples to test for heavy metals associated with mines and expects the results in the next few days.

McClain-Vanderpool said other tests conducted Monday showed the pH balance in the water — which would be affected by the presence of heavy metals — appeared to be within normal ranges.

Boulder County spokeswoman Carrie Haverfield said a county hazardous materials team and Nederland town officials also tested the water Monday and didn’t find anything that raised alarms.

Haverfield said that Boulder County is full of old mines, so some amount of seepage is likely.

“We did call in the proper resources and take the proper precautions we needed to take to ensure the safety of our residents,” Haverfield said.

McClain-Vanderpool added that the EPA and state mining and health officials visited the site Tuesday morning and are continuing to support local responders…

County officials responded to the area Monday after a plug came loose from the historic Swathmore mine, located near the 900 block of Bryan Avenue in the Eldora townsite.

Orange water flowed from the opening for about two-and-a-half hours on Monday, and officials temporarily shut down water intake systems for Nederland and Boulder while they tested the water.

A news release said county officials had been previously made aware of seepage from the mine.

The creek appeared orange on the bottom Tuesday afternoon, and a small culvert that runs into the creek was still full of rust-colored water and mud.

September 2013 flood: “It’s a nightmare we keep trying to wake up from” — Kitty Wang

Evans Colorado September 2013 via
Evans Colorado September 2013 via

From The Denver Post via the Loveland Reporter-Herald (Joey Bunch/John Aguilar):

As Colorado hits the two-year mark since a historic deluge swelled rivers and creeks to overflowing, killing 10 and causing nearly $4 billion in damage across 24 counties, frustration is a theme for a surprisingly large group of folks still dealing with the storm’s aftermath. Hundreds of mobile home park residents in Evans, a city of 20,000 south of Greeley, are unable to return to communities that have been effectively scraped off the map.

The major access road into Glen Haven is still being put back together, causing repeated daily hour-long delays that result in unending headaches for locals and drive away tourist traffic headed to or from nearby Estes Park.

Only three of 17 homes in James town destroyed by a manic James Creek have been completely rebuilt, and a part of the population has relocated or hasn’t yet moved back to the tiny mountain town.

And then there are the dozens of Lyons residents, locked in a seemingly endless bureaucratic arm-wrestling match with town officials over attempts to get permits to rebuild their homes.

They confronted town leaders at a public meeting earlier this month demanding a more streamlined process for evaluating and approving their engineering and hydrology plans so they can move forward.

“We’ve spent a lot of money on this project, and we haven’t laid a shovel in the ground,” said Kitty Wang, who with her husband has lived in Lyons for 13 years and still awaits a floodplain development permit for a new house. “It’s a nightmare we keep trying to wake up from.”[…]

Molly Urbina, the state’s chief recovery officer, acknowledged that despite the billions spent to make repairs and provide compensation to victims of Colorado’s most costly natural disaster, problems remain.

The state, she said, has not forgotten about those still suffering.

“When we talk about disasters, we talk about a marathon, not a sprint,” Urbina said. “We continue to coordinate with local communities to assess and evaluate needs and priorities and to advocate for additional resources.”

Some of those resources have come from groups like Foothills United Way in Boulder County, which has raised $4.9 million in donations and spent about $363,000 for mental health services. The charity still sits on nearly $2 million to help cover the costs of at least 333 open cases in Colorado’s hardest-hit county…

Urbina said estimating costs for a disaster the size of the 2013 floods, which destroyed 1,852 homes and 203 businesses and created more than 18,000 evacuees over a five-day period starting Sept. 10, 2013, is a “complex, long-term process.”

“We understood that this would evolve as recovery priorities and projects became more clear,” she said.

The dynamic nature of the floods’ impact has played out in dramatic fashion since the one-year anniversary, with the cost of rebuilding in Colorado swelling by a third to nearly $4 billion.

The $1 billion spike, Urbina said, reflects the fact that initial cost estimates done in the months following the flood were rough. In the past year, more detailed estimates of what it would cost to fully repair and restore roads and watersheds in the state were made.

Specifically, watershed recovery master plans performed over the last year revealed that the true cost of improving flood-impacted watersheds would amount to some $600 million.

Last February, Gov. John Hickenlooper announced $56.9 million will come from a federal program to help restore stream corridors and prevent future flooding.

The remainder of the increased cost estimate since last year — around $400 million — came about as the result of detailed design and engineering work, which more clearly outlined the cost of building roadways that can better withstand future flooding, Urbina said.

Work will begin soon to redesign U.S. 36 from Estes Park to Lyons at an estimated cost of $50 million.

Also, individuals and local governments have found damage they initially didn’t know about or thought private insurance would cover, according to the Colorado Resiliency and Recovery Office…

A new normal is also being pieced together in Evans, where the Eastwood Village and Bella Vista mobile home parks were turned from once-vibrant low-income neighborhoods to empty, weed-choked lots by the floods. It’s not certain what will happen to the two properties, though Bella Vista’s owner is working with the city to re-establish itself at the same spot on 37th Street.

Here’s a look at several survivors from Isa Jones and Pam Mellskog writing for the Longmont Times-Call via the Loveland Reporter-Herald.

Meanwhile the Big Dam repairs are nearly complete. Here’s a report from Saja Hindi writing for the Loveland Reporter-Herald. Here’s an excerpt:

Crews are putting the finishing touches on repairs to the Nelson Big Dam and expect to have them completed in the next few weeks.

The masonry arch dam, built in 1895, is located west of Loveland’s water treatment plant, and was significantly damaged in the September 2013 flood.

The dam diverts raw water to the city’s water treatment plant, provides drinking water for the Johnstown water treatment plant, and irrigates about 20,000 acres of farmland in Larimer and Weld counties.

The Consolidated Home Supply Ditch and Reservoir Co. owns the 60-foot-plus dam, which didn’t suffer major damages in the 1976 flood, but the 2013 waters left a lot of damage.

The dam is also identified as a Colorado Historic Civil Engineering Landmark, so crews had to make sure not to change the historic aspects of the dam substantially. That included using stones from the same quarry as the original stones.

Crews are working on Phase II of repairs now, according to Home Supply board member Gary Gerrard, which encompass the pointing or refacing of the dam (grouting stones on the face of the dam), a need caused by years of erosion. Once that’s completed, he said, crews will close the gate.

The dam was operational April 1, 2014, in time for the spring runoff, and repairs continued while it was in use, aside from taking a break in the winter months…

Some of the repairs after the flood damaged the dam, Gerrard said, included restoring the crest elevation, mitigating future flood effects by strengthening the dam with concrete abutments and installing a new spillway that configures water to go around instead of on top and updating to 21st century technology such as an automatic gate that fluctuates with river flow.

Because the flood damaged the dam’s main gate, the company was also able to replace other gates not damaged by the flood that were almost unusable and rusting because they were first put in 1915.

Funding for the repairs came from the city of Loveland, the Home Supply board, the Colorado Water Conservation board and the Federal Emergency Management Agency. The city committed to paying 50 percent of the costs not covered by federal and state grants. The conservation board committed to covering uncovered costs through long-term low-interest loans.

The total cost of repairs, Gerrard said, is about $3 million. Of that, $2.2 million is expected to be covered by federal aid.

Gerrard said the entities were able to keep costs low through “the methods of construction and the ability we had to be able to make decisions in the field, and the cooperation we had from all the entities to react to the things we found out in the field.”

Because officials could make decisions quickly, there weren’t a lot of construction holdups, he said.

From KWGN:

“That’s the main thing to reach out for help. They (Larimer County Long Term Recovery Group) connect you with the people you need (Loveland Housing, in particular). We had volunteers from Lyons, Minnesota, Wisconsin, Florida,” said Aleta.

Today, the Hammond’s have a little less privacy. The flood took out about half the trees and bushes along this road. And what was a pasture with a barn now looks like an outcropping of rocks.

That creek that once rushed with danger is nearly dry, but the family’s gratitude is overflowing.

People lost their homes, a few lost their lives. So we were very, very fortunate,” said Aleta…

The state repositioned U.S. 36 and Little Thompson River to prevent a tragedy like this from ever happening again.

The Hammonds say they still have work to do on their property, like foundation work, and cleaning off grit inside tools and motorcycles.

From the Loveland Reporter-Herald (Jessica Benes):

Where the Little Thompson River used to be 70 feet wide in places, it was blasted to 300 yards, according to Gordon Gilstrap of the Little Thompson Watershed Restoration Coalition.

The September 2013 flood devastated areas along Front Range rivers and streams, and while not nearly as many houses were lost on the Little Thompson River, landowners still are recovering from the deluge that destroyed vegetation, wildlife habitat and landscapes.

Some landowners along the Little Thompson call it “the forgotten river.”

“It’s been an interesting journey,” said Gilstrap, who helped set up the Little Thompson Watershed Restoration Coalition after the flood. “The Little Thompson has been an unknown river because no county or state roads run along it for any distance. It is all privately owned.”

Deirdre Daly, president of the coalition, said that because the river isn’t in a town or county that is leading the charge for river repair, the restoration has been almost entirely driven by the people who live on it…

The Little Thompson headwaters come in from several areas but are mostly above Big Elk Meadows below Estes Park, separate from the Big Thompson.

“It was a small working river,” Gilstrap said. “It provides drinking water to Big Elk Meadows and Pinewood Springs, irrigation to a lot of farmland. It has always been a small, quiet little river.”

The water pushed woody debris down the river, knocking out everything for hundreds of feet on both sides of the river.

Gilstrap said the land along the river was heavily wooded, with a lot of wildlife habitat, especially in the Big Elk Meadows, Pinewood Springs and Blue Mountain areas. Much of that habitat area was lost.

The number of homes lost in the flood was small — two to four — but there was a lot of other damage such as water in basements, homes partially damaged and agricultural fields that were made useless with sediment and garbage debris accumulation.

“A lot of agricultural equipment was lost, and the irrigation ditches took a real hit,” Gilstrap said. “An interesting fact most people don’t know is the Little Thompson was the river that shut down every county bridge between Big Elk Meadows and Milliken — seven public bridges and many other private bridges — so it cut off Northern Colorado from southern Colorado.”[…]

Watershed coalition

Gilstrap helped found the Little Thompson coalition in December 2013, starting with nothing. The group had no money and no knowledge of how to run a coalition.

“Thanks to an amazing group of volunteers that stepped forward to be a part of it, we established the Little Thompson coalition as one of the most effective coalitions in Colorado,” Gilstrap said.

With grant funding, the coalition oversaw the successful completion of a master plan for the watershed, started having meetings, published an active website and Facebook page and coordinated volunteer projects.

“We secured over $1.2 million in government and private-sector grants with a potential of $3 plus million to come,” he said.

The coalition also was able to hire a full-time watershed coordinator, Keith Stagg, and assistant coordinator. Erin Cooper, this summer to oversee grant raising and volunteers, which meant the hard workers such as Gilstrap who had volunteered so much of their time were able to step back.

“We all learned together (at the beginning),” Gilstrap said. “We even learned to say ‘fluvial geomorphic transition’ and other big words like that.”

He said there were two reasons for their success: the volunteers who stepped forward to be on committees while also working day jobs, and support from the state and counties involved.

“Everyone worked together, and that spirit is ongoing more than ever. The volunteers came in from everywhere and did the dirtiest, grungiest work imaginable and were happy as can be if you gave them water and cookies,” he said.

Work still to be done

One of the big problems the river still faces is sediment.

Gilstrap said the Big Thompson River has a rock base, while the Little Thompson has more of a soil base.

When the flood swept down the river from just below Estes Park, sediment traveled down, blocking irrigation canals and changing the bed of the river.

One of the private bridges in Berthoud — called the Green Monster bridge by locals — used to have a space large enough to walk under, and now a person can barely crawled under because of all the new sediment. Julie Moon used to walk her horse beneath the bridge.

“That all plugs up irrigation ditches, rechannels the river,” Gilstrap said. “It’s a long-term fight to understand what will happen with the sediment, how to fight it, how to do restoration so we don’t aggravate the problem.”

He said there is still a lot of farmland with sediment covering valuable cropland.

Natural Resources Conservation Service representatives walked the river and filled out disaster survey reports to define the work to be done. The restoration work will carry on for the next five or more years, he said. The river is also being analyzed for flood and fire resiliency, to be more resilient the next time a flood passes through.

“We’re trying to think during restoration how we can bounce back from them more quickly and not put people in as much peril,” Gilstrap said.

Stagg said the silver lining of the flood is that people are aware of the need for resiliency.

“Everyone wants to see the system put together,” he said.

Gilstrap said wildlife is coming back, and the coalition is looking at revegetation options to establish more wildlife habitat. They plan to use willow cuttings and other “ecotypical” seeds from Daly’s property and neighbors’ to vegetate other areas along the river with native plants.

Finding funding

Major sources of grants for restoration work has come from the U.S. Department of Housing and Urban Development, and from the Emergency Watershed Protection Program through USDA.

Gilstrap said a new round of grant funding from several sources will deliver possibly $47 million across Colorado, and he believes the Little Thompson might see $2 million to $3 million of that. Stagg and Cooper were hired through funding jointly from the state Department of Local Affairs and the Colorado Water Conservation Board.

“We’re one of (several) watersheds that received funding for professional staff,” Stagg said.

Each year, the coalition will receive grants and work on different pieces of the restoration project for many years to come.

“We will get a couple projects done in each round. Each year we will go find another source of money, and do a little bit of project as the years go on,” Daly said.

The Little Thompson even has a “Little Thompson Watershed” sign posted near the headwaters.

“We’ve never had that before,” Daly said. “Before, the river was there and hidden by trees and no one knew what river it was.”

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Post-flood master plans for three Boulder County creeks ready for review — Longmont Times-Call

From the Longmont Times-Call (Joe Rubino):

It’s been more than 15 months since Boulder County was wracked by historic rainfall that caused area creeks to jump their banks, and, in some cases, create new channels entirely, resulting in extensive damage to homes and infrastructure along the way.

Following an exhaustive public process, Boulder County officials announced earlier this month that they have finalized post-flood master plans for three local creeks: Fourmile, Left Hand and the St. Vrain.

The plans are meant to be comprehensive guides outlining how best to restore and stabilize the watersheds for each body of water, including recommendations for bank stabilization, debris removal, re-vegetation and even channel realignment on public and private properties.

While many of the individual projects contained in the plans are not funded, charting them out is expected to give stakeholders, especially municipalities, a leg up in securing the money needed.

“If we identify the improvements in the plans it makes it much more likely they will be funded by grants coming from the state and federal government,” Boulder County Transportation Director George Gerstle said.

Gerstle’s was among many county departments, including Land Use, Open Space, and Health and Environment, that contributed to drafting the master plans, but he credited the property owners and other groups concerned with the county’s environment with spurring the process forward.

“Though we lead the efforts it really was a coalition of all the property owners and all of the interest groups that really made this possible,” he said. “It was a pretty intensive effort by a lot of people to put together, but I think some pretty great documents have come out of it.”

The county also employed the services of engineering consulting firm Michael Baker for the process.

Naturally, there are many property owners who want to get to work on when the county’s various creeks and streams pass through their land, and Gerstle said the master plans are an important tool to make sure all work that is done has the entire watershed in mind.

“A lot of property owners want to do something to stabilize the creek and this provides guidance on how to do it while maintaining the environmental integrity,” he said. “One thing we learned is we can look at (the creeks) bit by bit, we have to see how it all works together.”

A creek of particular importance is the St. Vrain.

Gerstle pointed out that the stream completely changed its traditional alignment just west of Longmont, leading to heavy damage in the city. The master plan outlines steps to put it back in its channel and keep it there in a way the respects the natural environment.

Dale Rademacher, Longmont’s general manager of public works and natural resources, said he appreciated the opportunity for collaboration presented by the master planning process and the way it looked at the St. Vrain as a whole from it origins near the Great Divide down to it confluence with Boulder Creek.

“We’re pretty happy with the outcome. This is a foundational document necessary to go forward for state and federal funding and we think it serves that purpose pretty well,” he said.

Rademacher highlighted one project in the St. Vrain plan that he said could be underway next month. It involves creation of an overflow channel for Heron Lake that would direct flood waters away from Airport Road, an important street that still has flood barriers sitting alongside it just in case.

Rademacher said the Heron Lake project is intended to “intercept flood flows that may come through the area again,” and protect property nearby. He said the project, which is the subject to an intergovernmental agreement between city and county officials, is expected to cost around $700,000 and is being put out to bid within the next week with construction hopefully beginning in January.

More South Platte River Basin coverage here.

Boulder unveils flood mitigation plans; Council not on board

Surfing Boulder Creek September 2013 via @lauras
Surfing Boulder Creek September 2013 via @lauras

From the Boulder Daily Camera (Erica Meltzer):

The leading version of the South Boulder Creek flood mitigation project would remove 893 homes in southeast Boulder from the 100-year floodplain, but it would also involve building a 23-foot berm through a recognized state natural area with endangered tall-grass prairie habitat.

That was a step too far for Boulder City Council members, and on Tuesday night, they asked the city’s flood engineers to take up discussions with the University of Colorado about using land the university owns for its future south campus instead.

The council heard an update Tuesday on the city’s flood mitigation efforts in the aftermath of 2013’s damaging floods. Boulder remains one of the cities at highest risk for flash flooding in Colorado.

The most likely flood scenarios — and the ones the city’s mitigation efforts are designed to limit — involve intense rainfall over a short period of time, not the days of sustained rain the city experienced last year.

Several council members asked what the city could do about flooding from groundwater, which caused 47 percent of the damage last year, either directly or indirectly in the form of sanitary sewer backups.

The city’s wastewater utility has developed plans to line older clay pipes to reduce groundwater infiltration during large rain events, but there’s no practical or legal way to lower the groundwater table, Jeff Arthur, director of public works for utilities, told the council…

But Arthur stressed that the flood scenarios modeled by the city’s engineers and reflected in floodplain maps are both more likely to occur than an event like the 1,000-year rain of 2013 and more likely to produce significant damage and loss of life.

The flooding in most of Boulder’s major drainageways in 2013 was the equivalent of a 10- to 25-year flood event. Only Twomile Canyon Creek experienced a greater than 100-year flood, while South Boulder Creek, Goose Creek and Fourmile Canyon Creek experienced 50- to 100-year flooding.

The city is in the planning stages of four flood mitigation efforts: Boulder Creek, Bear Canyon Creek, Gregory Canyon Creek and South Boulder Creek.

Mitigation planning efforts on Upper Goose and Twomile creeks, Skunk Creek, King’s Gulch and Bluebell Creek will start in 2016, after floodplain map revisions along those watersheds are complete.

Gregory Canyon will present significant challenges because so many homes are so close to the creek, and it will be impossible to do a mitigation plan that takes those homes out of the 100-year floodplain, short of simply removing the homes, engineers told the council. Instead, engineers are looking for ways to break up the channels to reduce the impact of flooding there.

The South Boulder Creek mitigation planning process has been underway for several years, and consultants and the city’s Water Resources Advisory Board had settled on a $46 million recommendation that would involve a major regional detention area south of U.S. 36 and smaller detention areas near Manhattan Middle School and on the Flatirons Golf Course.

Modeling of likely flood scenarios indicate a 100-year flood of South Boulder Creek would cause $215 million in damage. City Council members watched an animated simulation that showed much of southeast Boulder filling with water.

However, the large detention facility would have a significant impact on open space owned by the city that includes endangered tall grass prairie habitat, wetlands areas and a number of endangered and threatened plant and animal species.

The open space board officially objected to the plan as proposed, and the water resources board revised its position, recommending that the upstream and downstream pieces of the project be separated.

The two smaller detention areas could be built for $23 million with relatively few regulatory hurdles and would still take 294 dwelling units out of the floodplain…

Councilman George Karakehian said building the berm through open space was not politically feasible.

“I think that would be a tough one to get built in our community,” he said.

A revised version of the South Boulder Creek mitigation plan is expected to be presented to the City Council later this fall.

More Boulder Creek coverage here.