Maintaining Storm Drainage

We purchased the home in August of 2014.
The development was created in 1985
The original development plans by "IDI" (Indigo Development Inc, the original developers) an approved by the "St. Johns River Water Management District" "SJWMD" show storm drainage swales between and at the rear of each lot.
The rear swales have specific development map, lower an lower elevations at specific development map, designated locations that terminate at and into a drainage pond.
Between my lot and the lot behind me, (we're at the starting end of the swale with 4 other lots with 6 lots total) to the drainage pond, its the homeowners responsibility to maintain their portion of the swale to keep an unobstructed flow to the pond.
Thru the years homeowners have not maintained the swale and a previous homeowner (not the one residing there now) on the lot next to mine had planted a hedge at the edge of the drainage swale and has grown an has intruded into the swale and has become the primary culprit in interfering with the flow of water to the drainage pond.
This is where it becomes convoluted, the swales were supposed to have been titled to and maintained by the city but they weren't, so they became private property and our (homeowners) responsibility.
There is only one homeowner that agrees that we need to to survey and reset elevations as per the development plans.
I've formally asked for help from "SJWMD", declined, the county, declined, the city, declined and the HOA, declined.
The "AMENDED DECLARATION OF COVENANTS, CONDITIONS, EASEMENTS AND RESTRICTIONS" read.
6.9 DRAINAGE. IDI reserves a seven and one-half (7-1/2) foot easement for storm drainage purposes along the side and rear lot lines of each platted lot. Lot drainage shall confirm to and not interfere with the engineered subdivision drainage. It shall be the homeowners responsibility to replace any fences, structures, or vegetation other than grass which might be damaged by the city of Daytona Beach in its maintain of the storm drainage system.
Thanks in advance for suggestions.

Sorry for posting names. I can't seem to find where I can edit my post to remove the names.
Speaking for myself personally, it wouldn't bother me if someone did put 2&2 together.
I'm not seeking legal advice, just a direction to go with this.
I don't really want to engage in a lawsuit with 4 other property owners if the entity I should hold responsible for the non action would happen to be the HOA, just saying?

I don't see where the homeowners are responsible for anything more than not allowing their lot drainage to interfere with subdivision drainage and replacing structures, fences, and vegetation if the city damages them. The second part seems to be moot since you said the city never took it over and does not maintain it.

Planting hedges that interfere with the drainage might be a violation but I would argue that hedges are not part of "lot drainage." There is that says owners have to maintain the swales so that they effectively drain.

The easement still exists so I would think either the developer or the HOA could come in and fix it but don't think you can force the individual owners to do so.

Why did SJRWMD decline to help? Are there any other easements noted on the plat? What does your Surface Water Management System permit say? These permits often have a list of restrictions attached that spell out who's responsible for what. I also don't see how the city's failure to maintain the swales ends up with the homeowners being responsible for them. The SJRWMD usually imposes "perpetual responsibility" on parties.

In my HOA, the stormwater drainage system is the perpetual maintenance obligation of the HOA. It's written right on the plat. If the responsibilities are different where you are, I think the SJRWMD documents, approved plans and permits should spell all that out somewhere.

I can vouch that there's at least one HOA in Florida that fits that bill.

If there was a stormwater system operation plan approved by the water management district, didn't it cover the private property in the development/subdivision back then? Something doesn't sound right.