LiDAR -- 15 Iowa Counties From: Andy Hatzos Date: Sun, 08 Dec 2024 03:51:18 MST On a bit of a roll right now. Here's an analysis of 15 Iowa counties, plus the HP of the capital city. Note that four counties -- Henry, Jefferson, Johnson, Wayne -- have new-identified HPs. --------------------------------------- Osceola IA (pb) / State High Point I previously did an analysis of the Iowa state high point using LiDAR data from 2009 -- back when I had time to create nice maps for my website. I found that Hawkeye Point was about a foot higher than two outlying points, one north and one south. Armed with newer data, I took a second look, and confirmed the same findings. I have the HP at 1670.2 ft at N43.460262 W95.708792, with the two outlying points each slightly more than a foot lower in elevation. (LiDAR: 2020 North Central Iowa) --------------------------------------- Dubuque IA (pb) Originally 4 areas. In open farmland with excellent data quality. The top two are too close to call, however. HP1 (PB Area 4): 1250.1 ft at N42.618641 W90.973572 HP2 (PB Area 3): 1249.8 ft at N42.612321 W90.983369 The two middle original areas (PB Areas 1/2) top out at about 1249 feet. (LiDAR: 2019 Eastern Iowa) --------------------------------------- Muscatine IA (pb) Originally 5 areas. The two southern areas (PB Areas 4/5) are physically gone, but there is additional artificial high ground due to a landfill in the vicinity. It can be ignored. The other three areas are very close together. Again, excellent data quality in open farm land, so I'll declare a single winner by about a foot over the other two spots. HP (PB Area 3): 808.9 ft at N41.570503 W90.880679 (LiDAR: 2019 Eastern Iowa) --------------------------------------- Henry IA (pb) Originally 1 area. However, a new HP has been identified to the southwest of the original contour. NEW HP: 801.6 ft at N40.938731 W91.407517 The highest point in the original contour area is 800.4 ft. The data quality here is good, and I'm comfortable declaring the new spot the sole HP. (LiDAR: 2019 Eastern Iowa) --------------------------------------- Jefferson IA (pb) Originally 4 areas. Got it down to two, but unfortunately, one of them is a new location. Western Candidate (PB Area 3): 815.9 ft at N41.160068 W92.156233 Eastern Candidate (NEW AREA): 816.1 ft at N41.131189 W92.071753 (LiDAR: 2019 Eastern Iowa) --------------------------------------- Washington IA (pb) Originally 4 areas. Confirmed the northernmost area (PB Area 2) as the sole winner. HP: 826.0 ft at N41.474450 W91.943370 The next highest area is about 822.3 feet. (LiDAR: 2019 Eastern Iowa) --------------------------------------- Johnson IA (pb) Originally 5 areas. All five original areas are eliminated, as the actual high point is on a hill just to their south. This hill has two distinct rises, and I will list them both. NEW HP 1: 910.4 ft at N41.820199 W91.806788 NEW HP 2: 910.2 ft at N41.818984 W91.805943 The highest of the original contours (PB Area 2) only reaches 906.3 ft. (LiDAR: 2019 Eastern Iowa) --------------------------------------- Iowa IA (pb) Originally 2 areas. This is a tough one, because the southern area (PB Area 2) is solidly higher than the northern area (PB Area 1). PB Area 2: 942.7 ft at N41.717173 W92.272699 PB Area 1: 940.8 ft at N41.763088 W92.296793 The problem is that I see evidence of terrain alteration for PB Area 2, and I think it's been raised up a bit. Because of that uncertainty, I think both areas still need to be in contention. (LiDAR: 2020 South Central Iowa) --------------------------------------- Wayne IA (pb) Originally 3 areas at 1120+ ft. This is one where the lay of the land doesn't match the original topo contours very well. The actual highest ground is all contained within a sprawling 1110+ ft contour that includes the original (and apparently erroneous) 1120+ ft contour marked as PB Area 1. Within this large area, there are a few distinct rises. Discounting an artificial rise near a house, I found three separate rises that are within a foot of each other and should be visited to claim the county. Listing these from west to east. New Spot 1: 1118.5 ft at N40.708176 W93.528122 New Spot 2: 1119.2 ft at N40.709056 W93.524686 New Spot 3: 1119.1 ft at N40.708816 W93.523535 Any other locations in the county are below 1118 feet. (LiDAR: 2020 South Central Iowa) --------------------------------------- Wapello IA (pb) Originally 12 areas. I got it down to two areas, both of which are in the far southwestern part of the county. Northern Candidate (PB Area 9): 929.2 ft at N40.905671 W92.639134 on the road surface, 927.8 ft at N40.906257 W92.638919 for more natural terrain in the field Southern Candidate (PB Area 1): 929.6 ft at N40.898869 W92.639073 on the road surface, 928.0 ft at N40.899174 W92.638280 for more natural terrain in the field The next highest area is PB Area 11, which tops out at 924.6 ft. (LiDAR: 2020 South Central Iowa) --------------------------------------- Mahaska IA (pb) Originally 6 areas. I can get this down to two areas, but they are inconveniently located at opposite ends of the county. To be honest, I'm somewhat confident the northern candidate is the winner, but there's just enough uncertainty to still list them both. Northern Candidate (PB Area 4): 916.6 ft at N41.486071 W92.675128 Southern Candidate (PB Area 6): 916.0 ft at N41.161051 W92.869713 The next highest area is PB Area 5, which tops out at 915.3 ft. (LiDAR: 2020 South Central Iowa) --------------------------------------- Dallas IA (pb) Originally 8 areas. The area at the far southwestern corner of the county is the winner. HP (PB Area 5): 1160.1 ft at N41.503686 W94.241502 on the road surface at the corner, 1158.1 ft at N41.503780 W94.241089 for more natural terrain at the edge of the field The next highest area is PB Area 2, which tops out at about 1156 ft. (LiDAR: 2020 North Central Iowa) --------------------------------------- Jasper IA (pb) Originally 6 areas. The westernmost area is the single winner. HP (PB Area 5): 1038.3 ft at N41.862154 W92.990126 The next highest point is PB Area 1 at 1037.0 ft. Note that the road surface near PB Area 2 reaches about 1039 feet, but it's clearly artificial and several feet higher than the surrounding land. (LiDAR: 2020 North Central Iowa) --------------------------------------- Allamakee IA (pb) Single original area (Iron Mine Hill) is confirmed as the winner with no changes. HP: 1342.5 ft at N43.302066 W91.462387 (LiDAR: 2019 Eastern Iowa) --------------------------------------- Polk IA (pb) 13 original areas. Can confirm a single winner. HP (PB Area 4): 1047.1 ft at N41.860562 W93.686309 The next highest area is PB Area 11 (the southernmost area) at 1045.6 feet. Nothing else surpasses 1045 feet. (LiDAR: 2020 North Central Iowa) --------------------------------------- Des Moines City HP (pb) The listed area on PB is near a water tower, but LiDAR shows this spot is lower than several other points in the city. Perhaps the city limits have changed over time? My pick for the HP is in somebody's backyard. 989.5 ft at N41.594201 W93.678045. The next highest point in the city is about 985 feet. The original water tower location only peaks out at about 980 feet. (LiDAR: 2020 North Central Iowa) --------------------------------------- Thanks, --Andy H