The La Plata County Commissioners voted Tuesday to update county regulations for development in 100-year flood zones, so that properties in those zones are eligible for national flood insurance.
This includes the residential area along Vallecito Creek, as well as the Pine River from Vallecito dam to the Ute Line just south of Bayfield.
County Emergency Management Director and Building Department Director Butch Knowlton clarified to the Times that Tuesday's vote did not include any changes to FEMA flood plain maps from 2010.
The regs tighten up requirements for new construction or substantial improvements within a 100-year flood zone, referred to as "special flood hazard areas." They also affect the smaller area identified as floodway. It also includes any modifications that could change how flood water flows, or how it backs up above the modifications. Efforts by one property owner to minimize flood impacts can push the impacts onto someone else's property.
"La Plata County has participated in the national flood insurance program since 1980," Knowlton told the commissioners. "We have to adopt federal and state updates" to maintain eligibility.
The county missed the January 2014 deadline to do that.
Knowlton said flood zone development is defined as any man-made change to improved or unimproved real estate. The goal is "to assure that development doesn't create any adverse impacts. Our department is charged with making sure homes and other structures are elevated above the 100-year flood level as established in the 1911 flood," he said.
"We've had previous flood plain studies and mapping since 1980, based on the 1911 flood as the base volume and flood plain areas," he said. "The most recent flood in 1970 was only 63 percent of what we anticipate in a 100-year flood. That was mainly on the Animas and Vallecito Creek.
"The regs have been in some ways very simple," Knowlton said. "We were informed by the Colorado Water Conservation Board (CWCB) that we had to go through this process, that were supposed to be in place by Jan. 14." CWCB listed 11 things the county didn't have in its 2010 regs.
Knowlton and attorney Todd Weaver presented the new version "that we feel is accurate and true and complies with the state and FEMA requirements. These are geared toward reducing damages and flood-proofing structures, and preventing adverse impacts on homes already built."
Knowlton continued, "There's a trend to trying to address the cumulative effect of all development in a flood plain area. Communities haven't looked at the long-term impact of more development in the flood plain. The new regs are geared to addressing the long-term impact."
The floodway is a central concern, the part of the 100 year zone with the highest debris movement, highest water velocity, and the most bank erosion.
"Changes in the new regs are specific to development in the floodway," Knowlton said. "In the old regs, there was a little bit of tolerance for that," such as upstream impacts from any obstruction. "The new regs address those obstructions to minimize the allowable increase from a 12-inch increase (in flood water level) down to six inches. That will be a significant issue in some areas of the county."
It will require more engineering to assure no more than the six-inch increase, Knowlton said. "To me, that's the most critical part of the changes. A lot of the 11 things are the need for additional engineering and additional proof of no adverse impacts in the floodway."
Weaver said CWCB had a model ordinance with minimum standards for eligibility for the national flood insurance program. "I compared those with our current code and made revisions to meet the minimum standards, so people can get flood insurance and possibly disaster funds and state grants."
Knowlton said when someone comes in for a building permit, "we go to our GIS (mapping) system to see if the building is in the flood plain area. We can do nothing without knowing the elevations on the property and the potential depth of flood waters. We'll probably have to direct (affected applicants) to a structural engineer to make sure (the building) will withstand the velocity of water and resist movement."
The Tuesday amendment specifies that any change or expansion of 10 percent or less does not need a land use permit.