Sedimentation Mucks Up St. Johns Tributaries
A watershed works like a funnel draining rainwater from an area into a big river - a main stem.
Water gets to the main stem through a system of creeks and streams - tributaries.
When those tributaries get clogged up - as some are in Northeast Florida - things don’t work like they should.
"Soil erodes. It has to go someplace," said Coastal Engineer Dr. Kevin Bodge. "It flows downhill - into rivers and streams."
Bodge said all kinds of stuff washes off into the tributaries - detritus from trees, oil and gas leaked onto the road, and trash.
"Where the water slows down, the sand and silt and clay drop out," said Bodge. "That eventually fills the area up with silt and muck and clay."
Bodge's colleague, Coastal Engineer Erik Olsen of Olsen Associates in Jacksonville, said it’s particularly problematic in the tributaries of the St. Johns River where there is lower flow and intense development.
"For example, if you go to the Ortega River. Fifty years ago it was mostly a sandy bottom," said Olsen. "If you look at it today it’s principally mud."
The sedimentation can impair a stream’s flow - or 'conveyance.'
"Think of it like a pipe," said Olsen. "Water flows well when the pipe is clear. But say you filled that pipe up halfway or three-quarters with sediment. It’s conveyance is significantly reduced."
That’s what’s been building up in Mike Webster’s mind - and in his backyard.
Webster lives on Fishweir Creek in Avondale. Sedimentation has filled in Fishweir Creek so much that nothing works like it used to: boats and manatees can’t get in and the water pooling in Webster’s yard doesn’t flow out.
In 2003, the Army Corps of Engineers and the City of Jacksonville came up with a plan to dredge Fishweir Creek. But 11 years on, nothing has been done.
"The restoration plan has been discussed and proposed since the '80s," said Webster. "We’re 15 or 20 years behind. It’s a matter of priorities."
Jacksonville City Councilman Jim Love is Chairman of the Waterways Committee. And he basically says - yes. It’s a matter of priorities.
"The cost is a little over seven million dollars. Right now, the money is not there."
Erik Olsen added:
"That’s one probably, if I had to bet, would never be built. It’s pretty low on the priority scale."
You can follow Peter Haden on Twitter @HadenMedia.