Two major regulatory changes that supporters and federal regulators say could lessen flood risks in Ascension Parish are on the ropes or already dead amid political pressure from builders and homeowners and under the weighty hammer of the parish president's veto.

In the 2½ years since the August 2016 flood inundated 6,200 homes and other buildings in Ascension, parish government has gotten behind major flood projects funded with federal dollars and made some regulatory changes but has been split or wholly against more aggressive measures.

Ascension's leaders, residents and business interests have engaged in a daunting back-and-forth over how to manage growth, respect land rights, and avoid the next flood in a parish where more than 70% of the land is in a high-risk flood zone. 

One of the proposed changes — limits on stacking up dirt to raise new homes — has been the cause célèbre of longtime homeowners, some Parish Council members and a batch of political candidates in this election year who have opposed standard building practices for major new neighborhoods.

After months of delay, Ascension takes 'big step' expanding limits on dirt use in parish's lowest areas

They say the practice of using dirt, or fill, to raise homes pushes water on older, lower homes, despite promises from builders and their engineers that detention ponds also built into the new neighborhoods store the extra water and mitigate that risk. 

After two years of review and delays, the council settled last month on new rules that would have put a 3-foot-deep limit on almost all fill and still required mitigation.

Builders charged the rules were ill-conceived and would fail even to achieve their goals, but the changes garnered little stated opposition from the administration.

Then, in a surprise move May 28, just before a parish home rule charter deadline, Parish President Kenny Matassa vetoed the restrictions.

Ascension Parish president vetoes expanded limits on using fill to elevate buildings

Matassa found the proposed rules, which would also require houses to be a built a foot higher than current requirements, were too onerous on homeowners for the proposed benefit in insurance savings. He also said they would create a series of implementation conflicts that would require more ordinance changes. 

"I have made this decision after considerable analysis and discussion with staff and consultants concerning the implementation and impacts of the amendments," Matassa wrote in his veto message.

The council is expected to consider whether to overturn his veto Thursday night, but it's not clear if the 11-member body will have the two-thirds majority necessary to do so.

Council members were closely split on key amendments that would have put teeth in the rules, though the vote on the final version of the rules drew no opposition.

A group of council members met with Matassa earlier this week, but say they have not come out with a compromise, though negotiations continue.

Ascension Parish council members surprised by president veto wonder if compromise possible

Matassa wants no fill in the Coastal Zone, the parish's swampiest, lowest land, and no net fill elsewhere, basically the parish's current practice and the one builders favor.

The other proposed change — new property development restrictions tied to updated federal flood insurance rate maps for the Sorrento, southern Gonzales and Burnside areas — came about last fall almost as an unintended afterthought.

Known as floodways, these changes are on the way out in face of strong outcry from longstanding homeowners.

The parish announced Tuesday that new maps without floodways were being made public for a required comment period that ends Aug. 21. A public viewing of the new maps, which also establish new flood elevations expected to lower flood insurance rates for more than 1,200 homes, is scheduled Monday from 5 p.m. to 6 p.m. at the Parish Governmental Complex in Gonzales.

Larry Larson, director emeritus and senior policy adviser for the Association of State Floodplain Managers, said floodways are the only way the National Flood Insurance Program blocks new construction in high-risk flood areas. 

Floodways are designed to prevent development inside the primary flow path of waterways during a 100-year flood, or a 1%-chance flood.

Larson said that if more development is added in these areas, more obstructions are created, so water levels must rise to find a way downstream. The higher water levels worsen flood impacts, but Larson said community leaders who oppose them often are looking at the loss in development opportunities and new tax dollars.   

"Floodways are anti-development. That's what they're intended to be: no development areas," he said. "Some communities and some states have a tendency to look the other way as much as they can, but I think, across the country, floodways are a key tool to avoid future increases in flood levels."

Parts of East Baton Rouge, Livingston and Tangipahoa parishes already have floodways established, including along the Amite River and White Bayou near Zachary.

Unincorporated areas or municipalities in 28 other parishes in Louisiana also have floodways, according to a Federal Emergency Management Agency listing, but not Ascension until the latest map revision for a small part of the parish. 

Yet, one of the strongest proponents of the fill ordinance, Councilman Bill Dawson, has been the primary supporter of removing the new floodways.

Constituents from his district objected to the unexpected restrictions on their land and the lack of notice parish government gave them before it appeared the changes were to take effect earlier this year.

Dawson said the parish's consultants informed him and others that floodways, which would have covered lands along Bayou Conway, the Panama Canal and Boyle Bayou, were required as part of the remapping effort. He only learned later they were optional, he said.

The remap wasn't about creating floodways, he said, but aimed at establishing benchmarks for the 100-year flood with the idea they would lower insurance rates. The new maps keep the newly created benchmarks, known as the base flood elevations, which didn't exist in the area previously. 

"That's the reason that we started this," Dawson said.

When asked about the long-term consequences of not having floodways, Dawson acknowledged that floodways could one day come to Ascension.

He said he wants conveyance paths for parish waterways identified so work can be targeted to minimize the width of those routes and also to inform growth decisions. 

"I mean we don't want to have, even if it's five or 10 years from now, for FEMA to come back and establish these floodways, and we find out we built a 100-lot subdivision in one of these places," Dawson said.

Follow David J. Mitchell on Twitter, @NewsieDave.