Thirty to one watershed to lake ratio likely means you're gonna need a big emergency spillway. Especially if you want to have only 2 or 3 inches deep during largest rain events. I have about seven to one ratio and have had several major flood events in just six years. Of course, I do have a constant low flow creek, which you may not.

What is your annual rainfall? How about soil types? Is the watershed mostly flat, or is there a pronounced slope? Do you have a flowing creek? If so, what is the flow rate? All will play a role in the answer.

Last edited by anthropic; 05/02/21 07:05 PM.
7ac 2015 CNBG RES FHM 2016 TP FLMB 2017 NLMB GSH L 2018 TP & 70 HSB PK 2019 TP RBT 2020 TFS TP 25 HSB 250 F1,L,RBT -206 2021 TFS TP GSH L,-312 2022 GSH TP CR TFS RBT -234, 2023 BG TP TFS NLMB, -160